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Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records
Open accessPublished version of a preprint
Abstract
We introduce the OSI-450, the SICCI-25km and the SICCI-50km climate data records of gridded global sea-ice concentration. These three records are derived from passive microwave satellite data and offer three distinct advantages compared to existing records: first, all three records provide quantitative information on uncertainty and possibly applied filtering at every grid point and every time step. Second, they are based on dynamic tie points, which capture the time evolution of surface characteristics of the ice cover and accommodate potential calibration differences between satellite missions. Third, they are produced in the context of sustained services offering committed extension, documentation, traceability, and user support. The three records differ in the underlying satellite data (SMMR & SSM/I & SSMIS or AMSR-E & AMSR2), in the imaging frequency channels (37 GHz and either 6 or 19 GHz), in their horizontal resolution (25 or 50 km), and in the time period they cover. We introduce the underlying algorithms and provide an evaluation. We find that all three records compare well with independent estimates of sea-ice concentration both in regions with very high sea-ice concentration and in regions with very low sea-ice concentration. We hence trust that these records will prove helpful for a better understanding of the evolution of the Earth's sea-ice cover.
Overview
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TL;DR
The paper introduces three new gridded global sea-ice concentration climate data records—OSI-450, SICCI-25km, and SICCI-50km—derived from passive microwave satellite data with dynamic tie points, per-pixel uncertainty estimates, and filtering information. Evaluation against independent 0 % and 100 % sea-ice concentration estimates shows good agreement, with SICCI-50km generally most accurate but at coarser spatial resolution.
Key findings
- The three CDRs differ in sensors, frequencies, resolution, and period: OSI-450 uses SMMR/SSM/I/SSMIS at 19/37 GHz on 25 km grids from January 1979 to December 2015; SICCI-25km uses AMSR-E/AMSR2 at 19/37 GHz on 25 km grids from June 2002 to October 2011 and July 2012 to May 2017; SICCI-50km uses AMSR-E/AMSR2 at 6/37 GHz on 50 km grids over the same AMSR periods.
- At open water (0 % SIC), OSI-450 and SICCI-25km have mean SIC of 0 % or −0.2 % in summer and ∼0.5 % in winter, with precision (1 standard deviation) of 1 %–2 %; SICCI-50km has summer ∼−0.5 % and winter 0.2 %–0.5 %, with the best precision.
- At closed ice (100 % SIC), SICCI-50km has the smallest bias, with mean SIC 99.5 % in the Arctic and 99.3 % in the Antarctic and standard deviation of the mean ∼2 % and ∼3 %; OSI-450 and SICCI-25km have mean SIC ∼98 % in the Arctic and ∼98.5 % in the Antarctic, with standard deviation of the mean 3.5 %–4.0 %.
- Algorithm uncertainty σ_algo is typically 2 %–3 % SIC, smearing uncertainty σ_smear reaches up to 40 % SIC at the ice edge, and total uncertainty is dominated by σ_smear; mean total uncertainty at 0 % SIC is ∼2 % in summer and ∼2.5 % in winter for OSI-450/SICCI-25km, and ∼1.5 % in summer and ∼2 % in winter for SICCI-50km.
Methods
- Input data are passive microwave brightness temperatures from SMMR, SSM/I, SSMIS, AMSR-E, and AMSR2, plus ERA-Interim 10 m wind speed, 2 m air temperature, and total column water vapour for atmospheric correction.
- The SIC algorithm is a hybrid, self-optimizing combination of a best-open-water algorithm and a best-closed-ice algorithm, with dynamic tie points trained separately per instrument and hemisphere using a [−7; +7 day] sliding window; processing includes RTM-based atmospheric correction, open-water filtering, a consolidated-ice-curve correction, land-spillover correction, and Level 2/3/4 gridding and gap filling.
- Evaluation uses the Round Robin Data Package v2 ground-truth locations for 0 % SIC (2002–2015) and 100 % SIC (2007–2016), plus time-series monitoring of algorithm tuning statistics and open-water-filter stability; uncertainties are evaluated against retrieval errors at 0 % and 100 % SIC.
Limitations
- The paper states that the open-water filter removes some true low-concentration ice, especially in the marginal ice zone, and this effect is not included in the uncertainty variables; melt-pond water is misinterpreted as open water, thin sea ice (<30 cm) is underestimated, and neither effect is included in the uncertainty fields.
- The paper states that interpolated values where satellite data were missing should be used with caution, especially spatial interpolation; uncertainty variables are not interpolated, and days with no satellite data are missing from the records. Land-spillover correction is imperfect, leaving some false coastal sea ice, especially for OSI-450 and SICCI-50km, and may remove some true coastal ice; fresh and brackish water ice is not handled with dedicated tie points.
- The paper states that evaluation covers only 0 % and 100 % SIC, not the intermediate marginal-ice-zone range, due to lack of high-quality validation data; uncertainties are slightly underestimated at 100 % SIC for OSI-450 and slightly overestimated at 0 % SIC. The text also makes evident that SICCI-50km’s open-water-filter temporal consistency is poorer because its SIC channels (6/37 GHz) differ from the 19/37 GHz channels used for the filter, and that atmospheric correction is less effective in the SMMR era.
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Claims the paper makes
93 Own interpretation · 76 No basis given · 57 Own result · 22 Own method · 12 Sources not found · 12 No full text of the sources · 8 Partly supported · 6 Supported · 5 Not checked yet · 3 Supported so far · 2 Couldn’t confirm · accuracy not yet measured
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In the paper
“In many cases, these algorithms are evolutions of those already applied in the previous version of the EUMETSAT OSI SAF CDR (OSI-409, Tonboe et al., 2016).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3 Algorithms and processing details
What the sources say
- Partly supportedcites Tonboe et al., 2016 sourceExperimental — accuracy not yet measured
Section 2.3 describes the EUMETSAT record’s hybrid Bristol–Bootstrap algorithm, supporting the claim that the record uses established sea-ice concentration algorithms. The References name OSI-409 and OSI-409a, but the paper does not say which algorithms OSI-409 used or establish that the algorithms in later SIC CDRs evolved from it. (LLM, conf=0.80)
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In the paper
“Niederdrenk and Notz (2018) found that observational uncertainty is the main source of uncertainty for estimating at which level of global warming the Arctic will lose its summer sea-ice cover.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 1 Introduction
What the sources say
- Supportedcites Niederdrenk and Notz (2018) source
Section 3.1 finds that the warming level for an ice-free summer Arctic differs more between observational estimates (about 1.7°C versus 2.3°C) than within the ensemble uncertainty range for the high-sensitivity estimate (1.5°C–1.9°C). The Summary also says observational uncertainty dominates additional uncertainty from internal variability. (LLM, conf=0.93)
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In the paper
“This is, for example, reflected by substantial differences between existing estimates of sea-ice concentration from various algorithms (e.g.Ivanova et al., 2015;Comiso et al., 2017b).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 1 Introduction
What the sources say
- Supportedcites Ivanova et al., 2015 source
Section 5.1 describes variability in sea-ice concentration produced by different algorithms and compares their sensitivity to error sources. The abstract also reports a systematic evaluation of 30 algorithms, supporting the claim that their estimates differ substantially. (LLM, conf=0.88)
- Not matchedcites Comiso et al., 2017b
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
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In the paper
“Satellite-retrieved records of Arctic and Antarctic sea-ice concentration differ widely in their estimates of a specific sea-ice concentration on a given day in a given region (e.g.Ivanova et al., 2015;Comiso et al., 2017a).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 1 Introduction
What the sources say
- Supportedcites Ivanova et al., 2015 source
The Introduction reports differences among sea-ice concentration algorithms of 5–12% at intermediate concentrations and up to 12% in a particular Arctic region. Section 4.1 also reports differing retrieval biases in both hemispheres. These passages support the broad point that satellite-derived records can give substantially different concentration estimates, though the size of the difference depends on conditions. (LLM, conf=0.86)
- Not matchedcites Comiso et al., 2017a
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
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The cited sources that could be checked couldn’t confirm or dispute this claim.
In the paper
“As in Tonboe et al. (2016), the CI training sample is based on the results of the NASA Team (NT) algorithm (Cavalieri et al., 1984): locations for which the NT value is greater than 95 % are used as a representation of 100 % ice (Kwok, 2002).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.3 Dynamical tuning of the SIC algorithm
What the sources say
- Not checked — no full text of the sourcecites Cavalieri et al., 1984 source
- Could not verifycites Kwok, 2002 sourceExperimental — accuracy not yet measured
The Data Sets and Approach section identifies the NASA Team algorithm, but does not describe a >95% threshold or closed-ice training samples. The Results and Discussion and Conclusions discuss uncertainty in winter-pack ice concentrations, without assessing whether NT values above 95% can represent 100% ice. Searches for the threshold and training-sample criterion found no such passage in our copy. (LLM, conf=0.76)
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In the paper
“Values of K were tuned using a footprint simulator and selected cloud-free scenes of the marginal ice zone imaged by the Moderate-Resolution Imaging Spectroradiometer (MODIS) as described in Tonboe et al. (2016).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.5 Uncertainties
What the sources say
- Partly supportedcites Tonboe et al. (2016) sourceExperimental — accuracy not yet measured
Section 1.4 describes selecting cloud-free MODIS scenes with different ice concentrations, and Section 2.4.2 describes using them in a satellite-footprint simulation. Those sections use the simulation to estimate smearing uncertainty; they do not say that values of K were tuned with it. (LLM, conf=0.86)
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- Partly supported
Every source the paper cites for this claim was checked and supports it.
In the paper
“A complete, 100 % cover of thin sea ice will be retrieved with a lower concentration, depending on the thickness (Ivanova et al., 2015).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.3 Caveats and known limitations
What the sources say
- Supportedcites Ivanova et al., 2015 source
Section 3.4 describes testing the algorithms on areas of approximately 100% thin-ice cover. Section 5.4 reports that the algorithms underestimated sea ice concentration for ice up to 35 cm thick and that their sensitivity varied with thickness. (LLM, conf=0.93)
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In the paper
“All SIC algorithms based on the passive microwave data are very sensitive to melt-pond water on top of the ice (Kern et al., 2016).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.3 Caveats and known limitations
What the sources say
- Partly supportedcites Kern et al., 2016 sourceExperimental — accuracy not yet measured
The Conclusions report that all eight algorithms investigated underestimated sea-ice concentration when melt ponds covered 40% of the ice. But the paper does not establish that all passive-microwave SIC algorithms are *very* sensitive: Section 4.3.3 says Near90_lin is sensitive only to some degree, and the Conclusions identify Bootstrap_p and NASA Team as having the lowest sensitivity. Page numbers were not supplied. (LLM, conf=0.88)
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In the paper
“Our algorithms do not rely on such a channel (Sect.3.4.2).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 2.1 Input satellite data
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In the paper
“Although not identical, the spatial resolution of the channels needed for the SIC algorithms is similar for the three coarse-resolution sensor series (SMMR, SSM/I, and SSMIS) with about 70×45 km instantaneous field-of-view (iFoV) diameters for the 19 GHz frequency channels, and 38 × 30 km for the 37 GHz ones (Table 2).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 2.1 Input satellite data
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In the paper
“We find that all three records compare well with independent estimates of sea-ice concentration both in regions with very high sea-ice concentration and in regions with very low sea-ice concentration.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > Abstract
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In the paper
“The second and third CDRs are called SICCI-25km and SICCI-50km.They are based on medium-resolution (15-25 km) PMW satellite data available from June 2002 onwards.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 1 Introduction
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In the paper
“Wintertime, monthly averaged maps of SIC ucorr exhibit systematic errors at high-concentration ranges, which are especially visible in the central Arctic Ocean.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.3 Reducing systematic errors at high-concentration range
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In the paper
“By varying θ the optimization process samples several planes and eventually returns the optimal angles θ OW and θ CI that respectively define the B OW and B CI algorithms.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
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In the paper
“Some low-concentration T B data (not shown, but falling between H and (A-D), closer to H) will also be detected as OW by the GR3719v test.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.2 Open-water filtering
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In the paper
“Likewise, the optimum rotation angle for CI cases is generally not the same as that corresponding to the BRI plane.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
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In the paper
“In between these two extremes, the B CI (T ) values oscillate between being below and over the SIC = 100 % line.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.3 Reducing systematic errors at high-concentration range
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In the paper
“The minimum of the blue and red curves are not achieved at the same angle.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
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In the paper
“Most of the OW T B data (grey triangle symbols) are thus flagged as OW, as expected.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.2 Open-water filtering
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In the paper
“A novel correction scheme is implemented as part of the second algorithm iteration (Fig. 2) that effectively mitigates most of these systematic errors over the basin.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.3 Reducing systematic errors at high-concentration range
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In the paper
“Figure 4 (right panel) also shows that the optimum rotation angle for OW cases is generally not exactly at θ = 0 • (BFM).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
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In the paper
“Our new algorithm is a generalization of BRI.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
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In the paper
“In the (19V , 37V ) diagram of Fig. 3, the GR3719v = T isolines are steeper than the consolidated ice line (A-D).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.2 Open-water filtering
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In the paper
“Despite using all the sensors, some data gaps still appear in the daily SIC maps, especially in the early part of the data record (late 1970s to mid-1990s).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.6 Other relevant algorithms and processing steps
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In the paper
“Both negative (blue) and positive (red) values appear that correspond to the intrinsic retrieval noise level of the SIC algorithm before the OWF is applied.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.1 The data records and selected examples
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In the paper
“It is noteworthy that the atmospheric noise reduction step does not much improve the OW standard deviation in the SH at the beginning of the OSI-450 period for the SMMR instrument (1979)(1980)(1981)(1982)(1983)(1984)(1985)(1986)(1987).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
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In the paper
“On Fig. 5 (right) we observe an overall increase of the DAL value from the Canadian Arctic Archipelago (multiyear ice) across the pole and towards the Laptev and Kara seas (first-year ice).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.3 Reducing systematic errors at high-concentration range
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In the paper
“Even if not as large as later in the time series, atmospheric correction does yield a positive impact on the accuracy of OW SICs during the SMMR era.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
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In the paper
“SICCI-25km (red) achieves roughly the same OW standard deviation as OSI-450.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
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In the paper
“The correspondence in the transitions of DAL values with the contour lines of sea-ice age is very good”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.3 Reducing systematic errors at high-concentration range
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In the paper
“The algorithm uncertainty is typically between 2 % and 3 % SIC.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.1 The data records and selected examples
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In the paper
“A value of K = 1 was found to yield good results for all three CDRs.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.5 Uncertainties
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“The total uncertainty, which is the sum (in variance) of σ algo and σ smear (Sect.3.5), is dominated by σ smear .”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.1 The data records and selected examples
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
- The authors state this as an assumption: The total uncertainty σ_tot is given by two uncertainty components, σ_algo and σ_smear.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The impact of the explicit correction of brightness temperature for atmospheric noise effects is also clearly visible in Fig. 8, since the standard deviations resulting from uncorrected T B data (thin solid lines) are consistently above those for corrected data (thick solid lines) by about 3 % to 4 % on average, depending on the season and hemisphere.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
boosteddirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“These raw values are non-physical (like the blue-shaded SIC <0 % values) and are set to exactly 100 % in variable ice_conc.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.1 The data records and selected examples
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“From Fig. 8, it is easy to see that the algorithms implemented in the three CDRs achieve zero bias (dotted lines along the y = 0 axis) for all instruments and both hemispheres on a daily basis.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
boosted- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The seasonal variability is also larger from the uncorrected data, especially in the NH.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“All three CDRs exhibit a negative bias, i.e. a modal SIC <100 %.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.2 Evaluation against ground truth
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“For sea ice, we find almost identical SIC distributions around 100 % for OSI-450 and SICCI-25km for both hemispheres (Fig. 11a, b, and d, e).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.2 Evaluation against ground truth
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Also without exception, mean SIC total uncertainties are smaller than 2 standard deviations of the retrieval errors (not shown).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.3 Evaluation of the uncertainties
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“For open water, we find quite similar SIC distributions around 0 % for all three CDRs for both hemispheres (Fig. 10).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.2 Evaluation against ground truth
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The SICCI-25km curves are also well below 15 %.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
boosted- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“However, a spatial sampling of 25 km does not fully represent the true spatial resolution of the product since the footprints of the SMMR, SSM/I, and SSMIS channels used by the algorithms are coarser (Table 2).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.3 Caveats and known limitations
plaindirect- Asserted: passes — The authors put it forward as true.
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The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“For sea ice, SIC = 100 % (Fig. 12c, d), we find that mean SIC total uncertainties for OSI-450 (∼ 3 %) are smaller than those for SICCI-25km (∼ 3.5 %) in both hemispheres.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.3 Evaluation of the uncertainties
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
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The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“For SICCI-50km mean SIC total uncertainties are smaller than for the other two CDRs -particularly in the Northern Hemisphere, at ∼ 2 % (Fig. 12c).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.3 Evaluation of the uncertainties
plain- Asserted: passes — The authors put it forward as true.
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A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“During summer (red curves) we find SIC distribution to be skewed to negative SIC for all CDRs except OSI-450 in the Antarctic.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.2 Evaluation against ground truth
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Distributions are generally more narrow for SICCI-50km than for the other two CDRs.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.2 Evaluation against ground truth
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Seasonal variations are visible especially at the beginning of the time series for NH cases, when typical winter values are around 7.5 % SIC and peak to 10 % SIC in summer.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“For OSI-450 and SICCI-25km, mean SIC total uncertainties are smaller than 1 standard deviation of the retrieval errors.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.3 Evaluation of the uncertainties
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Without exception the precision is better (smaller standard deviation) in summer than winter.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.2 Evaluation against ground truth
boostedcorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Figure 12 (a and b, black crosses) illustrates the very similar accuracies for OSI-450 and SICCI-25km with a mean SIC of 0 % or -0.2 % during summer and of ∼ 0.5 % during winter in both hemispheres.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.2 Evaluation against ground truth
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
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The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“All in all, we note that all three CDRs achieve a rather stable detection of true SIC mostly below the 15 % SIC threshold commonly used to define SIE.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
plain- Asserted: passes — The authors put it forward as true.
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A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Without exception mean SIC total uncertainties exceed 1 standard deviation of the retrieval errors (compare black and blue bars in Fig. 12a, b).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.3 Evaluation of the uncertainties
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“For SICCI-50km, mean SIC total uncertainties are comparable to (Fig. 12c) or larger than (Fig. 12d) 1 standard deviation of the retrieval errors.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.3 Evaluation of the uncertainties
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The standard deviation of the mean SIC (black bars), i.e. the precision, ranges between 1 % and 2 % for all three CDRs.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.2 Evaluation against ground truth
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“In addition, SICCI-50km also offers the smallest SIC standard deviation of the mean (black bars), i.e. the best precision, of ∼ 2 % and ∼ 3 % for the Arctic and Antarctic.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.2 Evaluation against ground truth
plain- Asserted: passes — The authors put it forward as true.
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A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“We note that the dynamic tuning of the OWF as implemented here secures a quite stable level for the minimum detectable true SIC, of the order of 10 % SIC, on average well below the 15 % SIC threshold commonly used for defining sea-ice extent.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.1 Discussion
plaindirect- Asserted: passes — The authors put it forward as true.
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The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“An analysis of the temporal consistency of the open-water filter (Sect.4.2.1) also revealed that our dynamic tuning of the OWF does not perform as optimally on the SICCI-50km CDR than on SICCI-25km and OSI-450.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.1 Discussion
plain- Asserted: passes — The authors put it forward as true.
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The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“We find in particular that our product has a long-term stable zero bias arising from the dynamical retuning of the tie points.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.3 Conclusions
plaindirect- Asserted: passes — The authors put it forward as true.
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The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“Second, the algorithm and the products are embedded into an operational context.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.3 Conclusions
plain- Asserted: passes — The authors put it forward as true.
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In the paper
“σ tot is dominated by the σ smear contribution.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.3 Conclusions
What the sources say
- Not matchedcites Fig. 7
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
plaindirectSingle case- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
- Not matched
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“In open-water conditions, the uncertainties provided in the CDR product files overestimate the observed retrieval noise by a couple of SIC percent (in terms of standard deviation).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.1 Discussion
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“This reduction in the variability comes in addition to the correction for the systematic errors (e.g.underestimation north of Canadian Arctic Archipelago; see left panel for which the ice curve correction was designed).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.3 Conclusions
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Over 100 % SIC, there is a close correspondence between the reported uncertainty and the observed retrieval noise for both hemispheres.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.1 Discussion
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“The self-tuning and self-optimizing algorithms also allowed consistent processing of SIC CDRs from the AMSR-E and AMSR2 instruments.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.1 Discussion
plaindirect- Asserted: passes — The authors put it forward as true.
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- Load-bearing: passes — The paper’s conclusions depend on it.
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A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“In the open-water regions of Fig.5(outside the 15 % SIC contour), the reduction in variability (centre panel) is even larger (3 %-4 % SIC) than over closed-ice regions.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.3 Conclusions
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Over open water, the retrieval accuracy of SICCI-50km is as good as 1 % to 1.5 % SIC (1 standard deviation).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.1 Discussion
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
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The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“All products contain per-pixel information on uncertainties arising from the algorithm itself at every time step (e.g.sensor noise or residual geophysical noise) and the smearing uncertainty from spatial remapping.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.3 Conclusions
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
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The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“For example, at every time step they include per-pixel information on the impact of possible filtering.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.3 Conclusions
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“A limited number of regions show no improvement (white colour) or slight degradation.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.3 Conclusions
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“In the regions covered with seaice (> = 70 % SIC), the shades of light blue indicate that the variability at high concentration is rather consistently reduced by about 1 %-2 % SIC by the ice curve correction”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.3 Conclusions
hedgeddirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
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- Based: passes — The paper gives a reason why it holds.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“Our evaluation results reveal very similar accuracies in the northern and southern hemispheres, even though the sea-ice conditions can be very different.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.1 Discussion
plain- Asserted: passes — The authors put it forward as true.
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- Load-bearing: passes — The paper’s conclusions depend on it.
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The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“First, the final products contain substantial information on the impact of the various processing steps.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.3 Conclusions
plain- Asserted: passes — The authors put it forward as true.
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A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“From the left panel, it appears that the atmospheric correction step on average increases SIC (shades of red) over open-water regions close to the sea-ice edge, e.g. in East Greenland Sea, Barents Sea, and in Labrador Sea.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.3 Conclusions
hedgeddirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“In particular, they were all developed with their primary application as climate-data records in mind, putting very narrow constraints on the permissible long-term drift of the records.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 1 Introduction
plaindirect- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“This is because both the bias correction of large-scale climate models and the extrapolation of observed relationships between forcing and sea-ice coverage can only be carried out robustly if observational uncertainty is sufficiently small.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 1 Introduction
plainconditional- Asserted: passes — The authors put it forward as true.
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In the paper
“since our algorithms do not require such stringent calibration thanks to using dynamic tuning (Sect.3.3).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 2.1 Input satellite data
plaindirect- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“There is thus no continuous data record of brightness temperatures in the vicinity of the water vapour absorption line (22.235GHz).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 2.1 Input satellite data
plain- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“However, the reliability and long-term stability of existing records is often not clear.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 1 Introduction
plain- Asserted: passes — The authors put it forward as true.
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In the paper
“Integrated over the entire Arctic, these differences accumulate up to a 20 % uncertainty in the long-term trends of sea-ice extent and seaice area (Comiso et al., 2017b)”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 1 Introduction
What the sources say
- Not matchedcites Comiso et al., 2017b
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
plaindirect- Asserted: passes — The authors put it forward as true.
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- Not matched
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Unavailability of ERA-Interim data prior to 1979 made it impractical to use the earliest period of SMMR data (October to December 1978).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 2.2 ERA-Interim data
plaindirect- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“(c) the capability to adjust to the climatological changes in the above-mentioned noise sources”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 1 Introduction
plaindirect- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“It is noteworthy that iFoV diameters, as reported in Table 2 and at several online resources, such as the WMO OSCAR Space-based Capabilities database, are not a measure of the true footprint of an individual measured pixel.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 2.1 Input satellite data
plain- Asserted: passes — The authors put it forward as true.
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In the paper
“For example, the albedo of the polar oceans is strongly influenced by sea-ice concentration (e.g.Brooks, 1925)”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 1 Introduction
What the sources say
- Not checked — no full text of the sourcecites Brooks, 1925 source
boosteddirect- Asserted: passes — The authors put it forward as true.
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The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“Our focus on sea-ice concentration is to a substantial degree driven by the fact that information on sea-ice concentration is key to the vast majority of approaches for understanding the changing sea-ice cover of our planet.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 1 Introduction
plaincorrelational- Asserted: passes — The authors put it forward as true.
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In the paper
“(b) low sensitivity to surface noise including wind roughening of the ocean surface, and variability of sea-ice emissivity and temperature”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 1 Introduction
plain- Asserted: passes — The authors put it forward as true.
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In the paper
“(d) a quantification of the remaining noise at each time step for each pixel.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 1 Introduction
plain- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Building CDRs from this suite of satellite sensors is best achieved if the selected algorithms only use channels that are consistently available throughout the period.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 2.1 Input satellite data
plainconditional- Asserted: passes — The authors put it forward as true.
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In the paper
“provide sea-ice concentration estimates with (a) low sensitivity to atmospheric noise including liquid water content and water vapour”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 1 Introduction
plain- Asserted: passes — The authors put it forward as true.
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In the paper
“This is at the cost of bringing a coarser spatial resolution into the algorithm.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
plaindirect- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“θ OW (blue disc) and θ CI (red disc) thus indeed define more accurate algorithms than BFM and BRI.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
plaindirect- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The role of the higher frequencies is to ensure a significant spread of the CI T B samples along the ice line and thus offer a good base for computing vector u with PCA.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
plaindirect- Asserted: passes — The authors put it forward as true.
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In the paper
“(c) cope with slightly different frequencies between different instruments (e.g.SMMR, SSM/I, and AMSR-E all have a different frequency around 19 and 37 GHz; see Table 2)”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.3 Dynamical tuning of the SIC algorithm
plaindirect- Asserted: passes — The authors put it forward as true.
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In the paper
“The closed-ice scatter also has increased variance directions, e.g.due to icetype and snow characteristics.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
plaindirect- Asserted: passes — The authors put it forward as true.
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In the paper
“This optimization step allows us to cope with the anisotropy of the OW and CI T B samples in the (19V , 37V , 37H ) T B space.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
plaindirect- Asserted: passes — The authors put it forward as true.
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None of the sources cited for this claim have been checked yet.
In the paper
“The weather filters (WFs) of Cavalieri et al. (1992) have been used in basically all available SIC CDRs except the earlier EUMETSAT OSI SAF data sets (Andersen et al., 2007;Ton-boe et al., 2016).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.2 Open-water filtering
What the sources say
- Not matchedcites Cavalieri et al. (1992)
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
- Not checked — no full text of the sourcecites Andersen et al., 2007 source
- Not matchedcites Ton-boe et al., 2016
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
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- Not matched
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“As seen in Fig. 3, this is not how the GR3719v filter works, as it will remove true sea ice as well, even in calm weather conditions (OW samples below J).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.2 Open-water filtering
plaindirect- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Our sliding window is made shorter so that tie points react more rapidly to seasonal cycles, e.g.onset of melting.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.3 Dynamical tuning of the SIC algorithm
plaindirect- Asserted: passes — The authors put it forward as true.
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What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“The value of 10 % SIC is chosen to be below the threshold commonly used for defining the sea-ice extent (15 % SIC) to ensure that the weather filter does not interfere when computing the sea-ice extent.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.2 Open-water filtering
plaindirect- Asserted: passes — The authors put it forward as true.
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None of the sources cited for this claim have been checked yet.
In the paper
“Recent investigations, e.g. during the ESA CCI Sea Ice projects, confirmed that NT was an acceptable choice for the purpose of selecting closed-ice samples.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.3 Dynamical tuning of the SIC algorithm
plain- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The role of the lower vertically polarized channel is to ensure a sufficient dynamic range between OW and CI signatures and thus aim to reduce retrieval noise.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
plaindirect- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“They also bring a higher spatial resolution to the retrieved SIC, since higher-frequency channels achieve higher spatial resolution (Table 2).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
plaindirect- Asserted: passes — The authors put it forward as true.
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The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“By construction, SIC algorithms BFM, BPM, BRI, and our new dynamic algorithms consider that the SIC is exactly 100 % when the input T B falls on the consolidated ice line (Fig. 3).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.3 Reducing systematic errors at high-concentration range
plaindirect- Asserted: passes — The authors put it forward as true.
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In the paper
“In addition, GR3719v contains information on sea-ice type (Cavalieri et al., 1984)”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.2 Open-water filtering
What the sources say
- Not checked — no full text of the sourcecites Cavalieri et al., 1984 source
plain- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Because of these anisotropies, the optimal projection plan will generally not be that of BRI.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
hedgeddirect- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“(d) mitigate sensor drift (if not already mitigated in the FCDR)”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.3 Dynamical tuning of the SIC algorithm
plaindirect- Asserted: passes — The authors put it forward as true.
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What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“Since the exact locations of H, A, and D vary for each instrument, hemisphere, and day in the data record, our threshold T will change (although slightly) during the whole data record, without the need for prescribed values (such as T = 0.05 for the Cavalieri, 1992 WF).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.2 Open-water filtering
plaindirect- Asserted: passes — The authors put it forward as true.
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- Load-bearing: passes — The paper’s conclusions depend on it.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“the correction of water vapour using ERA-Interim data is effective enough in polar regions so that very limited additional screening is triggered by GR2219v when applied after T B correction.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.2 Open-water filtering
plaindirect- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The dynamic training of our algorithms allows us to (a) adapt to interseasonal and interannual variations of the sea-ice and open-water emissivity”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.3 Dynamical tuning of the SIC algorithm
plaindirect- Asserted: passes — The authors put it forward as true.
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- Load-bearing: passes — The paper’s conclusions depend on it.
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What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“Our WF is tuned to avoid removing true ice with concentration larger than 10 %, on average.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.2 Open-water filtering
plaindirect- Asserted: passes — The authors put it forward as true.
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The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“a near 22 GHz channel is not available throughout the satellite time series (Sect.2.1)”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.2 Open-water filtering
plain- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“(b) cope with different calibration of different instruments in a series, or be-tween different FCDRs”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.3 Dynamical tuning of the SIC algorithm
plaindirect- Asserted: passes — The authors put it forward as true.
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In the paper
“The WF by Cavalieri et al. (1992) detects (and consequently forces SIC to 0 %) all observations with either GR3719v > 0.050 and/or GR2219v > 0.045 as open water.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.2 Open-water filtering
What the sources say
- Not matchedcites Cavalieri et al. (1992)
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
- Not matched
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Computing OWFs at Level 2 can also help to mitigate the potential impacts of changes in satellite crossing time between different missions.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.2 Open-water filtering
plainconditional- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The same reasoning can, however, be carried within other 3-D T B spaces, as long as such spaces offer a clustering of the CI conditions along an ice line and sufficient dynamic range between the OW signature and the CI line.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
plainconditional- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The open-water scatter has increased variance along the directions resulting from weather effects (including wind speed, cloud liquid water, and water vapour) on the emissivity of water.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
plaindirect- Asserted: passes — The authors put it forward as true.
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- Load-bearing: passes — The paper’s conclusions depend on it.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“This is a clear illustration that there cannot be a single SIC algorithm that performs best both on low-concentration and high-concentration conditions and confirms the strategy already adopted by Comiso (1986), Andersen et al. (2007), and Tonboe et al. (2016) to construct hybrid algorithms.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
boosted- Asserted: passes — The authors put it forward as true.
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What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“Such a method showed limitations and the new SIC CDRs now introduce explicit land spillover correction of the T B at all used channels and on swath projection.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.6 Other relevant algorithms and processing steps
plain- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“This means that sea-ice concentration will be consistently overestimated in coastal regions.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.6 Other relevant algorithms and processing steps
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
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The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“SMMR data for the period October to December 1978 are not included in the CDR because of the unavailability of ERA-Interim data for a correction of the atmospheric influence on T B (Sect.2.2).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.1 The data records and selected examples
plaindirect- Asserted: passes — The authors put it forward as true.
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What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“Our novel correction scheme moves the concept of an ice line to an ice curve that more closely follows the B CI (T ) samples along the u axis.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.3 Reducing systematic errors at high-concentration range
plaindirect- Asserted: passes — The authors put it forward as true.
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- Load-bearing: passes — The paper’s conclusions depend on it.
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A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Effect (a) is that the size of the footprint of the 19 GHz channels of the SMMR, SSM/I, and SSMIS instruments is larger than the resolution of the grid used to present the SIC field (25 × 25 km; see Table 1).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.5 Uncertainties
plain- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“This is expected from the choice of frequency channels, since SICCI-50km uses a C-band (6.9 GHz) channel, while SICCI-25km and OSI-450 use Ku-band (∼ 19 GHz).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
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In the paper
“By the same token, the monthly varying maximum sea-ice extent climatology implemented in Meier et al. (2017) was used as a basis for our own climatology.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.6 Other relevant algorithms and processing steps
What the sources say
- Not checked — no full text of the sourcecites Meier et al., 2017 source
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
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The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“However, it achieves a coarser spatial resolution (50 km) due to the limited size of the AMSR-E and AMSR2 antenna.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“This is very probably true low-concentration or thin sea ice that is removed by the OWF at the marginal ice zone.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.1 The data records and selected examples
hedgeddirect- Asserted: passes — The authors put it forward as true.
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In the paper
“The larger expansion in SH is to cope with the positive trends in the SH sea-ice extent (Hobbs et al., 2016).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.6 Other relevant algorithms and processing steps
What the sources say
- Not checked — no full text of the sourcecites Hobbs et al., 2016 source
plaindirect- Asserted: passes — The authors put it forward as true.
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- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“This term is derived from the accuracy (estimated as statistical variance) of the algorithm for retrieving 0 % (100 %) when applied onto the OW (CI) training data samples (Sect.3.3).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.5 Uncertainties
plaindirect- Asserted: passes — The authors put it forward as true.
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- Load-bearing: passes — The paper’s conclusions depend on it.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The off-range SIC values are also needed to compute temporal averages (e.g.monthly means) to avoid introducing biases if only SIC > = 0 % or SIC = <100 % values enter the averaging.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.1 The data records and selected examples
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
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The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“The central frequency of the AMSR-E and AMSR2 channels (18.7 GHz) is slightly further away from the water vapour absorption line (∼ 22 GHz) than the SSM/I and SSMIS channels (19.3 GHz).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Achieving zero bias despite the changes in central wavelengths and calibrations from one satellite to the next is one of the key advantages of using dynamically tuned algorithms (Sect.3.3).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The patterns seen in Fig. 7 are representative of the uncertainties of all three CDRs for both hemispheres during winter.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.1 The data records and selected examples
plaincorrelational- Asserted: passes — The authors put it forward as true.
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- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
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The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“Due to the coarse resolution of the sensors used, especially SMMR, SSM/I, and SSMIS (Table 2), the T B data are influenced by land emissivity several tens of kilometres away from the coastline.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.6 Other relevant algorithms and processing steps
plaindirect- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Three effects lead to better accuracies of SIC retrievals at low frequencies:”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
plaindirect- Asserted: passes — The authors put it forward as true.
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- Load-bearing: passes — The paper’s conclusions depend on it.
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What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“the threshold of the OWF is tuned dynamically against the daily updated training data samples (thus by instrument and by hemisphere) to preserve true SIC values down to 10 %.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“This is due to the training OW samples being selected in lower-latitude conditions (ocean surface, atmosphere conditions) rather than prevailing closer to the ice edge and is also discussed in Sect.4.2.3 when evaluating uncertainties.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.3 Reducing systematic errors at high-concentration range
plaindirect- Asserted: passes — The authors put it forward as true.
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- Load-bearing: passes — The paper’s conclusions depend on it.
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What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“As described in Sect.3.2 and 3.3, the algorithms implemented in the three CDRs dy- namically tune their parameters to yield zero bias and minimum standard deviation of the computed SICs (a.k.a.best accuracy) over the open-water (OW) and closed-ice (CI) training targets.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
plaindirect- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“SICCI-50km is designed to be the most accurate of the three SIC CDRs.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“A waterice separation limit at 10 % SIC is an ambitious goal but is necessary to ensure that time series of sea ice extent (SIE, usually defined with a threshold of 15 % SIC) are not influenced by the OWF and only by the evolution of true SIC.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
plaindirect- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The mismatch in frequency and resolution between the channels used to compute the OWF and those used to compute SIC explains the larger variability in the SICCI-50km time series in Fig. 9.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
plaindirect- Asserted: passes — The authors put it forward as true.
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The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“The radiation emitted at the wavelengths of the frequency channels comes from a very thin layer at the surface of the melt pond, which does not enable ocean water (in leads and openings) and meltwater (in ponds) to be distinguished.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.3 Caveats and known limitations
plain- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Trends in sea-ice decline (in the NH, especially summer) might thus have an amplification effect on the overestimation of the uncertainties, as the location for selecting training samples is increasingly further away from the sea-ice edge as decades pass.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.3 Evaluation of the uncertainties
hedgedconditional- Asserted: passes — The authors put it forward as true.
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What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“The uncertainty variables have larger values in the coastal regions where land spillover effects are detected.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.3 Caveats and known limitations
plaincorrelational- Asserted: passes — The authors put it forward as true.
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- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
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What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“The effect of the OWF is not included in the uncertainty variables, which pertain to the unfiltered (raw) ice concentration values.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.3 Caveats and known limitations
plain- Asserted: passes — The authors put it forward as true.
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In the paper
“The misinterpretation of meltwater on top of sea ice as open water is not included in the uncertainty variables (Q.Yang et al., 2016).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.3 Caveats and known limitations
What the sources say
- Not matchedcites Q.Yang et al., 2016
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
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- Not matched
In the paper
“Conversely to other CDRs (e.g.Meier et al., 2017 and its two algorithm components bootstrap and NasaTeam), the channels around 22 GHz are not used for filtering water vapour contamination.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.1 Discussion
What the sources say
- Not checked — no full text of the sourcecites Meier et al., 2017 source
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“We note that CI groundtruth data from East Antarctica are missing completely, however, because of a lack of SAR image acquisitions.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.2 Evaluation against ground truth
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
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What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“The effect of thin sea ice is not included in the uncertainty fields of the SIC CDRs.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.3 Caveats and known limitations
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“By the same token, some true coastal sea ice might be removed by the coastal correction scheme.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.3 Caveats and known limitations
hedgedconditional- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
In the paper
“Due to many factors (including smooth surface, absence of snow, brine content) concentration of thin sea-ice (<30 cm) is underestimated by most of the PMW SIC algorithms (Cavalieri, 1994).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.3 Caveats and known limitations
What the sources say
- Not checked — no full text of the sourcecites Cavalieri, 1994 source
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The ice_conc variable of the SIC CDRs should thus hold an estimate of 1 minus the open-water fraction in each grid cell, irrespective of whether this water is from lead and openings or ponds.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.3 Caveats and known limitations
plaincorrelational- Asserted: passes — The authors put it forward as true.
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In the paper
“This is one of the reasons why the Meier et al. (2017) data set only starts with SSM/I F08 on 9 July 1987 as a fully qualified CDR (according to https://nsidc.org/data/g02202, last access: 1 June 2018).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.1 Discussion
What the sources say
- Not checked — no full text of the sourcecites Meier et al. (2017) source
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
In the paper
“Aside from the technical aspects of reliably running the CDR processing chains on a daily basis, a major challenge that all SIC CDR data producers now face is the end of life for the U.S. Defense Meteorological Satellite Program (DMSP), which has been the workhorse for virtually all seaice CDRs since SSM/I F08 in 1987 (Table 2 and Fig. 1).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.2 Outlook
What the sources say
- Not matchedcites Table 2 and Fig. 1
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
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- Not matched
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“but in particular establishes clear rules on version tagging, documentation and availability of the underlying code, which allows other researchers to easily build on our work and to develop it further.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.3 Conclusions
plaindirect- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“It is in any case doubtful whether the resulting single CDR would meet the temporal consistency requirements of many climate applications.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.1 Discussion
hedged- Asserted: passes — The authors put it forward as true.
- Checkable: unclear — It is unclear whether it could be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“In particular, applying the same algorithm to microwave products based on different frequencies and satellites allows users to combine the advantages of the length of the record of the OSI-450 product with the high true spatial resolution of the SICCI-25km product and/or the low-noise product SICCI-50km.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.3 Conclusions
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“This is explained by the larger mismatch in frequency and resolution between the channels entering the SIC algorithms, and those used in computing the OWF (19 and 37 GHz only).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.1 Discussion
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The decision to produce distinct CDRs, one with SMMR, SSM/I, and SSMIS and the other two with AMSR-E and AMSR2 data, is mainly based on the difference in spatial resolution.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.1 Discussion
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“This reduction is the result of the atmospheric correction step, described in Sect.3.4.1.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.3 Conclusions
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“This slight overestimation is probably due to the use of a buffer zone outside of the monthly maximum ice climatology extent that dynamically selects the data samples used to train the algorithms (Sect.3.3) and derive uncertainties (Sect.3.5).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.1 Discussion
hedgedconditional- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The evaluation of uncertainties carried out in this paper provides some initial information on the remaining random per-pixel uncertainty, which can be used as an estimate of observational uncertainty, for example during model evaluation or data assimilation.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.3 Conclusions
hedged- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Long-term consistency is achieved by developing an algorithm that dynamically adjusts to changing environmental conditions and changing satellite sensors.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.3 Conclusions
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“the SIC after correction is a more accurate description of a nearly 100 % ice cover.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.3 Conclusions
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The analysis of the closedice (> = 70 % SIC) region in Fig.5thus confirms that the ice curve correction works as expected at high-concentration range”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.3 Conclusions
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“This is due to the training OW samples being selected in lower-latitude conditions (ocean surface, atmosphere conditions) rather than prevailing closer to the ice edge”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.3 Conclusions
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
In the paper
“It is noticeable that EPS-SG MWI implements quite a different channel frequency for Ka-band (26.5-40GHz): 31.4GHz instead of 36-37 GHz for SSM/IS and AMSRs (Table 2).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.2 Outlook
What the sources say
- Not matchedcites Table 2
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
- Not matched
- Probably not a substantial claim. 51
- It may state two separate claims as one. 99
The sources with a verdict support this claim; the rest weren’t checked yet, have no full text we could read, or their verdicts aren’t rated yet.
In the paper
“The L2 chain holds an iteration (marked by the”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.1 Overview of the processing chain
What the sources say
- Supportedcites Tonboe et al., 2016 source
Section 2.2 (page not provided) says sea ice concentration is solved by iteration and that Andersen et al. (2006b) describes the correction procedure in detail. This supports the claim that the cited workflow includes an iteration rooted in those developments. (LLM, conf=0.91)
- Not checked — no full text of the sourcecites Andersen et al., 2006 source
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
- Supported
The cited sources support only part of this claim — read each source’s verdict below.
In the paper
“In the Arctic the latter has been found to be linearly related to global-mean temperature (e.g.Gregory et al., 2002;Niederdrenk and Notz, 2018), atmospheric CO 2 concentration (e.g.Johannessen, 2008;Notz and Marotzke, 2012) and anthropogenic CO 2 emissions (Zickfeld et al., 2012;Herrington and Zickfeld, 2014;Notz and Stroeve, 2016).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 1 Introduction
What the sources say
- Not checked — no full text of the sourcecites Gregory et al., 2002 source
- Partly supportedcites Niederdrenk and Notz, 2018 sourceExperimental — accuracy not yet measured
Section 2.2 reports a linear relationship between global-mean temperature and Arctic sea-ice area in observations and simulations. The citing sentence refers to sea-ice extent, whereas the paper explicitly uses area rather than extent (Section 2.1). This citation is attached to the temperature relationship, not the separate claims about CO₂ concentration or emissions. (LLM, conf=0.86)
- Not checked — no full text of the sourcecites Johannessen, 2008 source
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
The cited sources that could be checked couldn’t confirm or dispute this claim.
In the paper
“OSI-450 has been released by the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) Ocean and Sea Ice Satellite Application Facility (OSI SAF, http://www.osi-saf.org/,last access: 15 June 2018) and is a fully revised version of its predecessor OSI-409 (Tonboe et al., 2016).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 1 Introduction
What the sources say
- Could not verifycites Tonboe et al., 2016 sourceExperimental — accuracy not yet measured
The Data availability section says the OSI SAF sea ice concentration record was available for download, and the References identify OSI-409a. The Future work section describes a later update as planned, but our copy does not mention OSI-450 or say that it was released as a fully revised version of OSI-409 (searched: OSI-450, OSI-409, revised version). (LLM, conf=0.74)
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
- Could not verify
The cited sources support only part of this claim — read each source’s verdict below.
In the paper
“While WFs are effective at removing false sea ice in openwater regions, they will always falsely remove (detect as open water) some amount of low-concentration (and/or thin) sea ice, especially along the ice edge (Ivanova et al., 2015).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.2 Open-water filtering
What the sources say
- Partly supportedcites Ivanova et al., 2015 sourceExperimental — accuracy not yet measured
Section 4.4 (page unavailable) says open-water/weather filters efficiently remove weather-related noise over open water, but also set some low-concentration ice pixels to 0% SIC. The paper does not establish that filters will always remove ice or that they specifically remove thin ice. The Introduction links low-concentration retrieval uncertainty to the marginal ice zone, but does not show that false removal is especially frequent at the ice edge. (LLM, conf=0.86)
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
- Partly supported
Every source the paper cites for this claim was checked and supports it.
In the paper
“Indeed, GR2219v is mostly effective at detecting water vapour effects, while GR3719v is effective at screening cloud liquid water and wind-roughening effects (Cavalieri et al., 1995).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.2 Open-water filtering
What the sources say
- Supportedcites Cavalieri et al., 1995 source
The Discussion of Results (Fig. 6) says the GR(22/19) threshold is effective only for water vapor. It also reports that the GR(37/19) threshold filters cloud liquid water and wind effects, among others. The claim accurately summarizes those distinct roles. (LLM, conf=0.92)
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
- Supported
Every source the paper cites for this claim was checked and supports it.
In the paper
“Note that, although this swath-based correction step is quite efficient at reducing land spillover contamination, a statistical method similar to that of Cavalieri et al. (1999) still had to be applied at Level 3; this is further discussed in Sect.5.2.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.6 Other relevant algorithms and processing steps
What the sources say
- Supportedcites Cavalieri et al. (1999) source
Section 3.3 describes an automated land-to-ocean spillover correction using a grid of coastal pixels and a matrix of minimum ice concentrations derived from monthly averages. That supports citing Cavalieri et al. (1999) as the model for a similar statistical correction. The swath-based step and its efficiency are the citing authors’ own description, not a finding attributed to this source. (LLM, conf=0.90)
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
- Supported
Every source the paper cites for this claim was checked and supports it.
In the paper
“However, there is no unique way to derive nor to present uncertainties in EO data (Merchant et al., 2017).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.5 Uncertainties
What the sources say
- Supportedcites Merchant et al., 2017 source
The Conclusion says methods of quantifying uncertainty vary across essential climate variables and that the form of uncertainty information must differ with the variable. Section 8 adds that no single strategy for providing uncertainty information is optimal for every variable. Together, these support the claim about deriving and presenting uncertainty in EO data. (LLM, conf=0.91)
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
- Supported
The sources with a verdict support this claim; the rest weren’t checked yet, have no full text we could read, or their verdicts aren’t rated yet.
In the paper
“All three share the same algorithm baseline, which is both a continuation of the EUMETSAT OSI SAF SIC approach (Andersen et al., 2006;Tonboe et al., 2016) and a series of innovations contributed to mostly by the ESA CCI activities.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.1 Discussion
What the sources say
- Not checked — no full text of the sourcecites Andersen et al., 2006 source
- Supportedcites Tonboe et al., 2016 source
The citation is attached to the claim that the algorithm baseline continues the EUMETSAT OSI SAF SIC approach. In Future work (page unavailable), Tonboe et al. state that the near-real-time OSISAF product and their climate data record use the same algorithms and similar methodologies. The later clause about ESA CCI innovations is not attributed to this citation. (LLM, conf=0.90)
plainn = 3- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
The cited sources support only part of this claim — read each source’s verdict below.
In the paper
“Among other data sets, the RRDP v2 holds ground-truth locations for openwater cases (OW, 0 % SIC) for the period 2002-2015, as well as ground-truth locations for closed ice (CI, 100 % SIC) for the period 2007-2016.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.2 Evaluation against ground truth
What the sources say
- Partly supportedcites Ivanova et al. (2015) sourceExperimental — accuracy not yet measured
Section 3.2 (page not provided) confirms that the RRDP contains open-water (0% SIC) and closed-ice (100% SIC) validation locations. It gives different coverage periods: open-water AMSR-E data cover 2002–2011, closed-ice AMSR-E data cover 2007–2011, and the full data set extends only through 2011. The paper does not establish the claimed RRDP v2 coverage through 2015 and 2016. (LLM, conf=0.88)
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
- Partly supported
The sources with a verdict support this claim; the rest weren’t checked yet, have no full text we could read, or their verdicts aren’t rated yet.
In the paper
“Mixing the two types of sensors (coarse resolution with medium resolution) into a single CDR would require careful consideration of the mismatch in spatial resolution and possibly advanced enhanced resolution methods (e.g.Long and Daum, 1998;Long and Brodzik, 2016), which are not used here.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.1 Discussion
What the sources say
- Not checked — no full text of the sourcecites Long and Daum, 1998 source
- Supportedcites Long and Brodzik, 2016 source
Section IV (Gridding and Reconstruction) identifies enhanced-resolution image reconstruction methods and explains that the high-resolution product optimizes resolution separately for each channel rather than forcing channels to match. This supports the citation’s role as an example of enhanced-resolution methods; the statement that those methods are not used in the citing study is the citing authors’ own description. (LLM, conf=0.90)
hedgedconditional- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
Every source the paper cites for this claim was checked and supports it.
In the paper
“Therefore, a very similar algorithm performance in both hemispheres is not a surprise and agrees with earlier findings (e.g.Ivanova et al., 2015).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.1 Discussion
What the sources say
- Supportedcites Ivanova et al., 2015 source
Section 4.1 reports closely matching standard deviations for the same algorithms in the Northern and Southern Hemispheres: 3.8% versus 3.5% for CV at 15% sea-ice concentration, and 3.1% versus 2.9% for BR at 75%. This supports the cited point about similar algorithm performance; “not a surprise” is the citing authors’ interpretation. (LLM, conf=0.88)
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
- Supported
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“The ERA-Interim reanalysis starts in January 1979 and is available throughout the time period of our CDRs.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 2.2 ERA-Interim data
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“It is noteworthy that the AMSR2 data are not from an FCDR, but rather from an archive of an operational data stream.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 2.1 Input satellite data
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“All three sea-ice concentration (SIC) CDRs share the same algorithms, processing chains, and data format.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 1 Introduction
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“first, all three records provide quantitative information on uncertainty and possibly applied filtering at every grid point and every time step.”
- Also stated in: § 1 Introduction · plain
“First, all our three records provide quantitative information on uncertainty and access to filtered as well a raw values at every grid point and every time step.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > Abstract
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
- Also stated in: § 1 Introduction · plain
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“The two medium-resolution radiometers AMSR-E and AMSR2 have finer resolutions at these channels (27 × 16 km and 14 × 9 km), accompanied by increased sampling (10 × 10 km instead of 25 × 25 km for SSM/I).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 2.1 Input satellite data
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“The first of our three climate data records (CDRs) is referred to as OSI-450.It is based on coarse-resolution (30-60 km) passive microwave (PMW) satellite data that are available from October 1978 onwards.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 1 Introduction
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“Vector u is computed by principal component analysis (PCA) and is the direction with highest variance in the CI T B samples.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“A new sea-ice concentration algorithm was developed during the ESA CCI Sea Ice projects and is used for the three CDRs.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“Conversely to BRI, we do not impose H on the projection plane.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“This iteration implements two key correction schemes: the atmospheric correction algorithm at low-concentration range (Sect.3.4.1)and a novel correction for systematic errors at high-concentration range (Sect.3.4.3).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.1 Overview of the processing chain
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. It may state two separate claims as one.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“Both T B spaces feature two higher-frequency channels with same wavelength but alternate polarization (37 GHz in both cases), and a lower-frequency vertically polarized channel (19V or 6V ).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“We call the SIC algorithm a hybrid algorithm because it combines two other SIC algorithms: one that is tuned to perform better over open-water and low-concentration conditions (named B OW for best open water), and one that is tuned to perform better over closed-ice and high-concentration conditions (named B CI for best closed ice).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“In winter Arctic conditions, it is typical to observe that B CI (T ) values are consistently lower than 100 % (down to 85 %-90 %) for old ice (low values of DAL) and consistently higher than 100 % (up to 105 %-110 %) for new and first-year ice (high values of DAL).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.3 Reducing systematic errors at high-concentration range
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“In that particular example, the improvement is mostly for OW conditions and limited for CI conditions.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
plaincorrelationalSingle case- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“The combination equation is quite simply a linear weighted average of B OW and B CI results, where w ow is the open-water weight and SIC is expressed as sea-ice fraction [0; 1]:”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“We rather rotate the plane around u and seek the optimum rotation an- gle θ that yields best SIC accuracy.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“Like in BRI we seek an optimum”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. It may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“However, careful analysis of the spread of consolidated ice samples along the ice line reveals that systematic deviations exist and are stable with time.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.3 Reducing systematic errors at high-concentration range
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The smearing uncertainty is largest, up to 40 % SIC, at the ice edge and low, near 0 % SIC, in areas where all contributing satellite footprints cover the same SIC (e.g.open water).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.1 The data records and selected examples
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“The same effect is observed for the standard deviations resulting from uncorrected SMMR T B data (purple thin line), which is consistent with a central frequency of 18.0 GHz (Table 2).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“These regions generally present negative SICs before correction and are brought closer to 0 % SIC by the process of atmospheric correction.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.3 Reducing systematic errors at high-concentration range
plaindirect- Asserted: passes — The authors put it forward as true.
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The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“The SICCI-50km SIC has increased granularity due to the lower resolution of the 6 GHz channels compared to the 19 GHz channels.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.1 The data records and selected examples
plaindirect- Asserted: passes — The authors put it forward as true.
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Probably not a substantial claim. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“The two SIC fields on the top row are rather similar except in the marginal ice zone, where the higher resolution of the AMSR2 instrument (SICCI-25km) with respect to that of the SSMIS (OSI-450) leads to resolving finer details.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.1 The data records and selected examples
plaindirect- Asserted: passes — The authors put it forward as true.
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Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“This difference in frequency yields better accuracy for SICCI-25km than OSI-450 when using uncorrected T B data (not shown) but this effect is mostly cancelled after atmospheric correction (though not fully in SH, bottom panel).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
plaindirect- Asserted: passes — The authors put it forward as true.
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In the paper
“During summer, σ algo is larger by a few percent, and the increased variability inside the ice pack yields higher σ smear , leading to larger σ tot .”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.1 The data records and selected examples
plaindirect- Asserted: passes — The authors put it forward as true.
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- The authors state this as an assumption: The total uncertainty σ_tot is given by two uncertainty components, σ_algo and σ_smear.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“It is lower for sea ice than for open water because the global variability of closed sea ice is lower than the SIC variability over open water.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.1 The data records and selected examples
plaindirect- Asserted: passes — The authors put it forward as true.
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In the paper
“The time series in Fig. 8 illustrate that the algorithms behave as expected across instruments and are effectively tuned to achieve zero bias and a small retrieval noise for each instrument in the time series.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
plain- Asserted: passes — The authors put it forward as true.
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In the paper
“Over closed-ice conditions (inside the 70 % SIC isoline), the regional patterns of the correction are clearly visible and seem to match variations in sea-ice age”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.3 Reducing systematic errors at high-concentration range
boostedcorrelational- Asserted: passes — The authors put it forward as true.
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In the paper
“SICCI-50km (green) is more accurate than both SICCI-25km and OSI-450, by nearly 1 % in NH and 0.5 % in SH.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
plaincorrelational- Asserted: passes — The authors put it forward as true.
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A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“OSI-450 and SICCI-25km provide a slightly larger bias with a mean SIC of ∼ 98 % in the Arctic and ∼ 98.5 % in the Antarctic, which also comes with a higher SIC standard deviation of the mean: 3.5 % to 4.0 %.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.2 Evaluation against ground truth
plaincorrelational- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Distributions for SICCI-50km are considerably narrower (Fig. 11c, f) and, in comparison to OSI-450 and SICCI-25km, have a modal value closer to 100 %.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.2 Evaluation against ground truth
plaincorrelational- Asserted: passes — The authors put it forward as true.
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In the paper
“For SICCI-50km, the accuracy varies more than for the other two CDRs: summer is ∼ -0.5 % and winter is 0.2 % to 0.5 %.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.2 Evaluation against ground truth
plaincorrelational- Asserted: passes — The authors put it forward as true.
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A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Figure 12c, d further illustrate that SICCI-50km provides the smallest bias (best accuracy) in both hemispheres with mean SICs of 99.5 % and 99.3 % for the Arctic and Antarctic.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.2 Evaluation against ground truth
plain- Asserted: passes — The authors put it forward as true.
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In the paper
“For open water, SIC = 0 % (Fig. 12a, b), we find that mean SIC total uncertainties differ by less than 0.3 % between OSI-450 and SICCI-25km and take values of ∼ 2 % during summer and of ∼ 2.5 % during winter.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.3 Evaluation of the uncertainties
plain- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“However, coastal correction procedures are not perfect, and some false sea-ice remains along some coastlines, especially for OSI-450 and SICCI-50km because of the larger footprint of the instruments.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.3 Caveats and known limitations
plaindirect- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“Although the filter is efficient at detecting and removing weather-induced noise (false ice) over open water, it also has the effect of removing some amount of true low-concentration ice, especially in the marginal ice zone.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.3 Caveats and known limitations
plaindirect- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“For SICCI-50km, the mean SIC total uncertainty is smaller than for the other two CDRs -particularly during summer in the Northern Hemisphere, with ∼ 1.5 % compared to ∼ 2 % in winter.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.3 Evaluation of the uncertainties
plain- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The SICCI-25km curves are close to the OSI-450 ones, but at a slightly larger value of 11 %, with a seasonal variation range of about 2 %.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
plaincorrelational- Asserted: passes — The authors put it forward as true.
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- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
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It may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“For both hemispheres, we find that the precision of OSI-450 and SICCI-25km SIC CDRs are similar to each other and poorer than for SICCI-50km, which is in line with the findings in Fig. 8.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.2 Evaluation against ground truth
plain- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“They are in any case well below the 15 % threshold throughout the data record and very little change is observed when transitioning between sensors.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
plain- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“The footprint of the AMSR-E and AMSR2 channels used in the ESA CCI CDRs (SICCI-25km and SICCI-50km) are much more compatible with the 25 × 25 km (SICCI-25km) and 50×50 km (SICCI-50km) target grids, so that their grid spacing is closer to the true resolution.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.3 Caveats and known limitations
plaindirect- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“During winter (blue curves) OSI-450 and SICCI-25km are skewed a bit towards negative SIC in the Arctic but not in the Antarctic.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.2 Evaluation against ground truth
plain- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The OSI-450 curves are very stable with time and increase only slightly from around 9 % SIC at the beginning of the period to around 10.5 % SIC at the end.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
plaindirect- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
In the paper
“Although there was always at least one satellite mission carrying a relevant passive microwave instrument after October 1978, a few data gaps exist in the satellite data record that are too short to appear in Fig. 1.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.3 Conclusions
What the sources say
- Not matchedcites Fig. 1
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
plain- Asserted: passes — The authors put it forward as true.
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- Load-bearing: fails — The paper’s conclusions may not depend on it.
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Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
- Not matched
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“These regions generally present negative SICs before correction and are brought closer to 0 % SIC by the process of atmospheric correction.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.3 Conclusions
plaindirect- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“Based on similar frequency channels at 19 and 37 GHz, the OSI-450 and SICCI-25km CDRs achieve similar accuracies, both in the time-series plots of internal tuning parameters (Sect.4.2.1) and when validated against ground-truth (Sect.4.2.2).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.1 Discussion
plaindirect- Asserted: passes — The authors put it forward as true.
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A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Over consolidated sea ice, the retrieval accuracy is somewhat poorer (3.5 % to 4 % SIC) and has limited low bias (2 % SIC in NH, 1 % in SH).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.1 Discussion
plain- Asserted: passes — The authors put it forward as true.
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A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Over open water, the retrieval accuracy of these two CDRs is as good as 1.5 % to 2 % SIC (1 standard deviation) and without biases.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.1 Discussion
plain- Asserted: passes — The authors put it forward as true.
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A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Time-series plots document that the dynamic tuning of the SIC algorithms and of the OWF perform as expected, and that temporal consistency is mostly achieved despite the changes of channel frequencies and calibration between sensors.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.1 Discussion
plain- Asserted: passes — The authors put it forward as true.
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The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“Uncertainties are systematically documented in the final products and have carefully been evaluated.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.3 Conclusions
plain- Asserted: passes — The authors put it forward as true.
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A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Over consolidated sea ice, the accuracy is better than 2.5 % SIC and the bias is limited to below 1 %.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.1 Discussion
plain- Asserted: passes — The authors put it forward as true.
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It may state two separate claims as one.
In the paper
“Overlap of satellite missions and the 9-month data gap between AMSR-E and AMSR2 operations are clearly visible from Fig. 1.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.3 Conclusions
What the sources say
- Not matchedcites Fig. 1
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
boosted- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
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Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
- Not matched
In the paper
“In their most recent update (GCOS-IP, 2016), they request that reliable observational records of sea-ice concentration are made available to the climate research community.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 1 Introduction
What the sources say
- Not matchedcites GCOS-IP, 2016
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
plain- Asserted: passes — The authors put it forward as true.
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Probably not a substantial claim. The paper’s conclusions may not depend on it.
- Not matched
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Slight changes in incidence angle or wavelengths between the sensor series can be compensated for by the algorithms, but it is harder or even impossible to achieve temporal consistency in the event of sudden loss of channels.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 2.1 Input satellite data
plainconditional- Asserted: passes — The authors put it forward as true.
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A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“which hinders a robust evaluation and bias correction of climate models, and in particular hinders a robust estimate of the future evolution of the Arctic sea-ice cover.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 1 Introduction
plaindirect- Asserted: passes — The authors put it forward as true.
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None of the sources cited for this claim have been checked yet.
In the paper
“These data are also at the heart of the two currently most widely used seaice concentration algorithms, namely the NASA Team algorithm (Cavalieri et al., 1984) and the bootstrap algorithm (Comiso et al., 2017b).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 1 Introduction
What the sources say
- Not checked — no full text of the sourcecites Cavalieri et al., 1984 source
- Not matchedcites Comiso et al., 2017b
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
plaincorrelational- Asserted: passes — The authors put it forward as true.
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- Load-bearing: fails — The paper’s conclusions may not depend on it.
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Probably not a substantial claim. The paper’s conclusions may not depend on it.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“For any of these applications, the reliability of the underlying sea-ice concentration record is crucial.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 1 Introduction
plain- Asserted: passes — The authors put it forward as true.
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Probably not a substantial claim. It may be too vague to check against evidence.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“Scattering, reflection, and emission in the atmosphere add or subtract contributions to the radiated signal, and challenge our ability to accurately quantify seaice concentration.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 2.2 ERA-Interim data
plaindirect- Asserted: passes — The authors put it forward as true.
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Probably not a substantial claim. It may state two separate claims as one.
In the paper
“the 23.0 GHz channels of the SMMR instrument have been highly unstable since their launch, and eventually ceased to function on 11 March 1985 (Njoku et al., 1998).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 2.1 Input satellite data
What the sources say
- Not matchedcites Njoku et al., 1998
Couldn’t be matched to a paper in Crossref, so it can’t be checked.
plain- Asserted: passes — The authors put it forward as true.
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- Load-bearing: passes — The paper’s conclusions depend on it.
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It may state two separate claims as one.
- Not matched
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“Third, they are produced in the context of sustained services offering committed extension, documentation, traceability, and user support.”
- Also stated in: § 1 Introduction · plain
“Third, they are produced in the context of sustained services offering committed extension, documentation, traceability, and user support.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > Abstract
plain- Asserted: passes — The authors put it forward as true.
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Probably not a substantial claim.
- Also stated in: § 1 Introduction · plain
In the paper
“Such a wavelength is typically used in filtering weather effects in other SIC CDRs (e.g.Meier et al., 2017).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 2.1 Input satellite data
What the sources say
- Not checked — no full text of the sourcecites Meier et al., 2017 source
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In the paper
“These two SICCI CDRs are released by the European Space Agency (ESA) Climate Change Initiative (CCI, http://cci.esa.int/, last access: 15 June 2018) programme.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 1 Introduction
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In the paper
“Second, they are based on dynamic tie points, which capture the time evolution of surface characteristics of the ice cover and accommodate potential calibration differences between satellite missions.”
- Also stated in: § 1 Introduction · plain
“Second, they are based on dynamic tie points, which capture the time evolution of surface characteristics of the ice cover and help to minimize the impact of sensor drift and change in satellite sensor.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > Abstract
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- Also stated in: § 1 Introduction · plain
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In the paper
“Building a consistent data record requires methodologies that carefully intercalibrate and tune the algorithms to yield similar results when using all these sensors.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 2.1 Input satellite data
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“as is much of the heat and moisture transfer between the ocean and the atmosphere (e.g.Maykut, 1978).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 1 Introduction
What the sources say
- Not checked — no full text of the sourcecites Maykut, 1978 source
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In the paper
“The effective field-ofview (eFoV) diameter includes the two effects and is a better measure of the true footprint of the instrument.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 2.1 Input satellite data
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In the paper
“The values of θ OW and θ CI will vary with the exact frequencies, calibration, or viewing angle of the instrument (Table 2), as well as with the OW and CI signatures that exhibit regional, seasonal, and interannual variations.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
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In the paper
“The varying signature of sea-ice and ocean emissivity with time and hemisphere, the different frequencies of the 19 and 37 GHz channels for different instruments, and the varying effects of atmospheric correction all prevent the adoption of fixed thresholds.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.2 Open-water filtering
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In the paper
“The new hybrid, self-optimizing algorithms described in this section can always be tuned to available training data (see Sect. 3.3) and deliver optimum and time-consistent performance.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
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In the paper
“These fields can and will typically exhibit data gaps, e.g. in case of missing satellite data.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.1 Overview of the processing chain
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In the paper
“The NOAA/NSIDC sea ice concentration CDR uses the Cavalieri et al. (1992) thresholds, with the exception of Southern Hemisphere processing for SSMIS F17, where the GR3719v threshold is set to 0.053 (Algorithm Theoretical Basis Document for Meier et al., 2017).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.2 Open-water filtering
What the sources say
- Not matchedcites Cavalieri et al. (1992)
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- Not checked — no full text of the sourcecites Meier et al., 2017 source
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In the paper
“(e) compensate for trends potentially arising from the use of NWP reanalysed data to correct the T B (see Sect. 3.4.1).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.3 Dynamical tuning of the SIC algorithm
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In the paper
“For example, Spreen et al. (2008) adapted the GR3719v threshold to 0.045 and GR2219v to 0.040 when processing seaice concentration with AMSR-E data.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.2 Open-water filtering
What the sources say
- Not checked — no full text of the sourcecites Spreen et al. (2008) source
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In the paper
“This, however, fails to recognize that the scatter of the closed-ice points around the line and that of open-water T B samples around the point H are anisotropic in the (19V , 37V , 37H ) T B space.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.2 A hybrid, self-tuning, self-optimizing sea-ice concentration algorithm
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In the paper
“All T B data falling below the GR3719v isoline will result in GR3719v > T and will thus be flagged as OW (SIC = 0 %) by the GR3719v test.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.2 Open-water filtering
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In the paper
“This is a better approach than computing WFs from daily averaged gridded T B data, which will smooth and smear the sea-ice edge region, as well as rapidly changing weather effects such as cloud liquid water content or wind roughening.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.2 Open-water filtering
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In the paper
“This is an illustration of how WFs based on this gradient ratio will not only successfully detect false sea ice as open water, but also wrongly result in ice-free conditions where some true sea ice should have been observed.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.2 Open-water filtering
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In the paper
“indicating that a combination of DAL (right panel) and ice curve correction (left panel) could be used for sea-ice type (if not age) classification studies.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.3 Reducing systematic errors at high-concentration range
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In the paper
“Spatially and temporally varying uncertainty estimates for each and every SIC value are required of state-of-the-art CDRs (GCOS-IP, 2016).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.5 Uncertainties
What the sources say
- Not matchedcites GCOS-IP, 2016
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In the paper
“It is noteworthy that full advantage of the overlap of satellite missions (see Fig. 1 and Table 2) was taken in order to reduce the occurrence of missing data areas as much as possible in the daily composited fields.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.6 Other relevant algorithms and processing steps
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In the paper
“This consolidated ice curve defines the SIC 100 % isoline during the second iteration of Level 2, and -conversely to the atmospheric correction described in Sect.3.4.1 -has the greatest effect on consolidated ice regions.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.3 Reducing systematic errors at high-concentration range
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In the paper
“Several other proxies for the local variability of the SIC field (among others the 3×3 standard deviation, the Laplacian, and power-tomean-ratio) were tested and this one was selected for its simplicity and robustness.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.5 Uncertainties
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In the paper
“Prior to further describing Fig. 8, it is important to note that the biases and standard deviations discussed here are internal to the processing chains, not an evaluation of the CDRs against independent observations of SICs.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
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In the paper
“The emissivity of land is comparable to sea-ice emissivity and much higher than water emissivity.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.6 Other relevant algorithms and processing steps
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In the paper
“The parameterizations implemented in the SMMR RTM are probably less developed than in the SSM/I and SSMIS RTM, which might explain why the impact on our standard deviation is more limited for SMMR.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
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In the paper
“We note that clear-sky radiances from SSM/I and SSMIS were directly assimilated in ERA-Interim over the ocean (Dee et al., 2011) but not SMMR radiances (P. Poli, personal communication, 2018).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
What the sources say
- Not checked — no full text of the sourcecites Dee et al., 2011 source
- Not matchedcites P. Poli, personal communication, 2018
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In the paper
“Intuitively, both effects should have no or limited impact where the sea-ice cover is homogeneous (fully consolidated sea ice or open water).It should be at a maximum where sharp spatial gradients occur, typically at the sea-ice edge.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.5 Uncertainties
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In the paper
“Since SICCI-25km uses very similar frequency channels to those of OSI-450 (Table 1), it is not surprising that they achieve similar accuracy.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
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In the paper
“Still in Fig. 5 (centre panel), the increased variability (red tones) between the 15 % and 70 % isolines follows logically from the two above-mentioned reductions: the corrections enable more accurate retrievals of SICs; thus the ice edge is more sharply defined in the daily SIC fields, and this results in higher variability on a monthly basis.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.3 Reducing systematic errors at high-concentration range
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In the paper
“Another plausible explanation is that the reanalysed fields for wind speed and water vapour from ERA-Interim are less accurate in the SMMR era than in the SSM/I and SSMIS era.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
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In the paper
“As noted at the end of Sect.3.4.1,OSI-450 uses the Wentz (1983) RTM for SMMR, and the Wentz (1997) RTM for SSM/I and SSMIS.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
What the sources say
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In the paper
“Effect (b) is that the footprint of the 37 GHz channels is smaller than that of the 19 GHz ones, so that the two frequencies entering the SIC algorithms do not cover the same area of the Earth's surface.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.5 Uncertainties
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In the paper
“The consolidated sea-ice samples we extract dynamically for [-7; +7 days] sliding windows (Sect.3.3) will typically exhibit more variability due to shorter-term changes in sea-ice signatures.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.3 Reducing systematic errors at high-concentration range
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In the paper
“In addition, the ice curve in Fig. 3 is fitted through the consolidated ice points from the ESA CCI Sea Ice RRDP (Pedersen et al., 2018) that spans several years and winter months and thus illustrates an average sea-ice curve.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 3.4.3 Reducing systematic errors at high-concentration range
What the sources say
- Not checked — no full text of the sourcecites Pedersen et al., 2018 source
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In the paper
“A key asset of the algorithms we adopted is that they are selftuning and self-optimizing to the data, which greatly helps temporal consistency to be achieved between different satellite missions, both in the past and future (discussed later in Outlook, Sect.5.2).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.1 Discussion
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In the paper
“Using the status_flag variable, any SIC contaminated by land spillover effects or with high air temperatures were discarded.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.2 Evaluation against ground truth
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In the paper
“The true resolution of the SICCI-25km CDR might be slightly better than 25 × 25 km, but this grid spacing was retained to ease uptake by users and comparison with OSI-450.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.3 Caveats and known limitations
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In the paper
“The retrieval of ice area fraction in these conditions would call for dedicated tie points (e.g.Ghaffari et al., 2011), which we did not implement here.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.3 Caveats and known limitations
What the sources say
- Not matchedcites Ghaffari et al., 2011
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hedged- Asserted: passes — The authors put it forward as true.
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In the paper
“The mismatch of grid spacing to the true resolution of the instrument footprint is taken into account in the uncertainty model of the OSI SAF CDR and is a key contribution to the smearing uncertainty (Sect.3.5).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.3 Caveats and known limitations
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- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Because the locations for ground-truth estimates are generally not at the ice edge, the smearing uncertainty term is close to zero and σ algo dominates the evaluation results summarized in Fig. 12.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.3 Evaluation of the uncertainties
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“We note in addition that both the OSI-450 and SICCI-25km CDRs dynamically tune their optimal data planes for low-concentration range θ OW in the (19V , 37V , 37H ) 3-D T B space, while the OWF is only tuned in the (19V , 37V ) T B plane.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“The CI locations are selected in areas of high sea-ice concentration and after 24 h of convergent sea-ice motion, as computed from a highly accurate SAR-based sea-ice drift product from the Copernicus Marine Environment Monitoring Service (CMEMS, http://marine.copernicus.eu,last access: 15 June 2018).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.2 Evaluation against ground truth
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. It may state two separate claims as one.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“For SIC = 100 % cases, the dynamically selected training samples are spread mostly all over the high sea-ice concentration regions, and there are thus good odds that the training samples are representative of the geophysical conditions in the ground-truth data set, and that in turn the reported uncertainties are in agreement with the retrieval errors for SIC = 100 % cases.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.3 Evaluation of the uncertainties
hedgedconditional- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“These results are in agreement with those introduced in Sect.4.2.1 and are mainly explained by the frequency channels used in the three CDRs: 18.7 GHz for SICCI-25km, instead of 19.3 GHz for OSI-450 (less noise contribution from atmospheric water vapour content), and 6.9 GHz for SICCI-50km (lower sensitivity to atmosphere and surface snow and seaice property variations).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.3 Evaluation of the uncertainties
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“The OSI-450 data set currently covers 1979 to 2015 with a consistent set of frequencies at 19 and 37 GHz.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.1 Discussion
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“The OW locations are situated just outside the climatological mask delineating maximum sea-ice extent but well inside the buffer zone added to it in Sect.3.6.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.2 Evaluation against ground truth
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
What the paper did — it cites no source for this, so there is none to check. The quote shows it is in the paper.
In the paper
“For the evaluation at 100 % SIC conditions, we collocated the SIC CDRs with the SAR-based CI locations in the RRDP v2 for months November to March (Arctic) and May to September (Antarctic) in the same way as we did for open water; no spatial or temporal interpolations are performed.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.2 Evaluation against ground truth
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The departure of the optimal SIC plane from the OWF plane (by convention at θ = 0 • ; see right-hand panel in Fig. 4) could be the cause for the slight increase of the 1 % percentile curves of OSI-450 during the time period (via an improvement of the reanalysis data entering the atmosphere correction step over time), and the different value obtained with SICCI-25km.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
hedgedconditional- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Thus, the results summarized in Fig. 12 indicate that the uncertainty σ tot provided with the three CDRs are slightly underestimated, especially for OSI-450 for the high sea-ice concentration range (SIC = 100 %), and are slightly overestimated for the low sea-ice concentration range (SIC = 0 %).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.3 Evaluation of the uncertainties
hedgedcorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The temporal stability of the time series in Fig. 9 documents that the tuning of the OWFs at values close to 10 % SIC is successful for the two data records that rely on the 19 and 37 GHz for computing their SICs (OSI-450 and SICCI-25km) and is not as good for SICCI-50km, which uses the 6 and 37 GHz channels to compute the SIC values.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.2.1 Monitoring stability and internal consistency
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“In addition to the difficulty of computing dynamic tie points over such small areas, it is unclear if such dedicated tie points would make a large difference in the end, because of the combination of many error sources in these closed water bodies (land spillover, thin sea-ice, larger atmospheric influence, etc.).”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.3 Caveats and known limitations
hedged- Asserted: passes — The authors put it forward as true.
- Checkable: fails — It may be too vague to check against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. It may be too vague to check against evidence. The paper’s conclusions may not depend on it.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“The 23.0 GHz channels of the SMMR instrument have been highly unstable since their launch and eventually ceased to function in March 1985.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.1 Discussion
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“Ice resulting from freezing of fresh and brackish waters does not have the same emissivity as that from seawater.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 4.3 Caveats and known limitations
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: fails — The paper may give no reason why it holds.
Probably not a substantial claim. The paper may give no reason why it holds.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The SICCI-50km is thus the most accurate of our three new CDRs but also has the coarsest spatial resolution due to the large footprint of the 6 GHz channels.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.1 Discussion
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“and is potentially linked to the age of sea ice.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.3 Conclusions
hedgedcorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“However, because our algorithms self-adapt to the data and their calibration, the implementation with MWI should be possible.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.2 Outlook
hedgedconditional- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: fails — The paper may give no reason why it holds.
Probably not a substantial claim. The paper may give no reason why it holds.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The almost 15-year record of brightness temperature observations from these two instruments is a key complement to OSI-450.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.1 Discussion
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it.
The paper states this without a source or data behind it here, so there is nothing to check it against. The quote shows it is in the paper.
In the paper
“Theoretically 6 GHz is a better channel for estimating sea-ice concentration since the atmosphere is more transparent, the influence of error sources like seaice age or snow processes have less influence, and the contrast between ocean and ice is larger.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.1 Discussion
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“This guarantees ease of a long-term maintenance of these products”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.3 Conclusions
boosteddirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: fails — The paper may give no reason why it holds.
Probably not a substantial claim. The paper may give no reason why it holds.
The authors state this as an assumption.
The total uncertainty σ_tot is given by two uncertainty components, σ_algo and σ_smear.
“we make the assumption that the total uncertainty σ tot is given by two uncertainty components.”
The paper relies on this without support.
The temporal consistency of the minimum detected SIC has not been documented for other available CDRs, although all use OWFs.
“To the best of our knowledge the temporal consistency of the minimum detected SIC has not been documented for other available CDRs, although all use OWFs.”
The paper relies on this without support.
Such 3-D-based filters do not exist at present.
“Such 3-D-based filters do not exist at present and this is addressed as future work in Sect.5.2.”
The paper relies on this without support.
All the aspects listed below apply generally to the other existing SIC data records based on PMW satellite data.
“All the aspects listed below apply generally to the other existing SIC data records based on PMW satellite data.”
Self-check
Percentages, sums and reported differences re-computed from the paper’s own numbers.
Each contradiction between two passages listed here was confirmed by an independent check.
Rated major: it would touch a result — a value a result rests on, reported and recomputed p-values on opposite sides of the significance level, two passages that conflict with no sign which is right, or a cited work retracted before this paper was published.
In the paper
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 2.1 Input satellite data
“The AMSR-E data we use are the NSIDC FCDR AE_L2A V003 FCDR by Ashcroft and Wentz (2013), covering the full lifetime of the mission from 1 June 2002 to 4 October 2011.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.3 Conclusions
“| EOS Aqua | 1 June 2002 | 3 October 2010 | 6.9 (75 × 43), 18.7 (27 × 16), | 89.5 • | 55 • | |”
Rated minor: it would not touch a result — a value no result rests on, a p-value that stays on the same side of the significance level, or a conflict that is clerical, resolved elsewhere in the paper, or outside its own findings.
In the paper
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 2.1 Input satellite data
“covering 23 July 2012 until 15 May 2017, that is the end of the SICCI-25km and SICCI-50km CDRs.”
§ Version 2 of the EUMETSAT OSI SAF and ESA CCI sea-ice concentration climate data records > 5.3 Conclusions
“| GCOM W1 | 23 July 2012 | 31 May 2017 | 6.9 (62 × 35), 18.7 (22 × 14), | 89.5 • | 55 • | AMSR2 operated |”
Citations
Cites
The ERA‐Interim reanalysis: configuration and performance of the data assimilation system
Dee, D. P., Uppala, S. M., Simmons, A. J., Berrisford, P., Poli, P., Kobayashi, S., Andrae, U., Balmaseda, M. A., Balsamo, G., Bauer, P., et al. (2011) · Quarterly Journal of the Royal Meteorological Society · doi:10.1002/qj.828 · Cited by 24,480
International Journal of Remote Sensing
(2011) · International Journal of Remote Sensing · doi:10.1080/01431161.2012.638113 · Cited by 1,895
Sea ice remote sensing using AMSR‐E 89‐GHz channels
Spreen, G., Kaleschke, L., & Heygster, G. (2008) · Journal of Geophysical Research: Oceans · doi:10.1029/2005jc003384 · Cited by 1,676 · cited 3×
“This is the essence of the dynamic tuning approaches adopted in Tonboe et al. (2016) and further developed for the new CDRs (Sect.”
MethodInfluentialSelf-citationThe Operational Sea Surface Temperature and Sea Ice Analysis (OSTIA) system
Donlon, C. J., Martin, M., Stark, J., Roberts-Jones, J., Fiedler, E., & Wimmer, W. (2012) · Remote Sensing of Environment · doi:10.1016/j.rse.2010.10.017 · Cited by 1,394 · cited 1×
“New land masks for the target 25× 25 km grids (one for NH and one for SH) were computed based on the Operational Sea Surface Temperature and Sea Ice Analysis (OSTIA) 0.05×0.05◦ land mask (Donlon et al., 2012).”
InfluentialA well‐calibrated ocean algorithm for special sensor microwave / imager
Wentz, F. J. (1997) · Journal of Geophysical Research: Oceans · doi:10.1029/96jc01751 · Cited by 837 · cited 14×
“The tie points for applying the NT algorithm to SMMR, SSM/I, and SSMIS are taken from Appendix A in Ivanova et al. (2015).”
MethodInfluentialLarge Decadal Decline of the Arctic Multiyear Ice Cover
Comiso, J. C. (2011) · Journal of Climate · doi:10.1175/jcli-d-11-00113.1 · Cited by 811 · cited 4×
“For easing later discussion, we note here that in winter Arctic conditions, the typical multiyear sea-ice signature is to the “left” of the ice line -close to A- while first-year sea ice and young sea ice is to the right -closer to D- (Comiso et al. 2012). 5 The left-hand panel of Figure 4 is originally adapted from S…”
BackgroundMethodInfluentialDetermination of sea ice parameters with the NIMBUS 7 SMMR
Cavalieri, D. J., Gloersen, P., & Campbell, W. J. (1984) · Journal of Geophysical Research: Atmospheres · doi:10.1029/jd089id04p05355 · Cited by 748
Energy exchange over young sea ice in the central Arctic
Maykut, G. A. (1978) · Journal of Geophysical Research: Oceans · doi:10.1029/jc083ic07p03646 · Cited by 657 · cited 2×
“By the same token, the monthly varying maximum sea-ice extent climatology implemented in Meier et al. (2017) was used as a basis for our own climatology.”
BackgroundMethodObserved Arctic sea-ice loss directly follows anthropogenic CO 2 emission
Notz, D., & Stroeve, J. C. (2016) · Science · doi:10.1126/science.aag2345 · Cited by 603 · cited 3×
“Johannessen, 2008; Notz and Marotzke, 2012) and anthropogenic CO2 emissions (Zickfeld et al., 2012; Herrington and Zickfeld, 2014; Notz and Stroeve, 2016).”
BackgroundSelf-citationTrends in the sea ice cover using enhanced and compatible AMSR‐E, SSM/I, and SMMR data
Comiso, J. C., & Nishio, F. (2008) · Journal of Geophysical Research Atmospheres · doi:10.1029/2007jc004257 · Cited by 548 · cited 6×
“BFM and BPM are widely used for sea-ice monitoring in what is commonly known as the bootstrap algorithm (Comiso and Nishio, 2008).”
MethodInfluential
Cited by
Sorted by citations
The Arctic has warmed nearly four times faster than the globe since 1979
Rantanen, M., Karpechko, A. Y., Lipponen, A., Nordling, K., Hyvärinen, O., Ruosteenoja, K., Vihma, T., & Laaksonen, A. (2022) · Communications Earth & Environment · doi:10.1038/s43247-022-00498-3 · Cited by 3,317
Seland, Ø., Bentsen, M., Olivié, D., Toniazzo, T., Gjermundsen, A., Graff, L. S., Debernard, J. B., Gupta, A. K., He, Y., Kirkevåg, A., et al. (2020) · Geoscientific model development · doi:10.5194/gmd-13-6165-2020 · Cited by 1,066
The EC-Earth3 Earth system model for the Coupled Model Intercomparison Project 6
Döscher, R., Acosta, M., Alessandri, A., Anthoni, P. M., Arneth, A., Arsouze, T., Bergman, T., Bernardello, R., Boussetta, S., Caron, L., et al. (2022) · Geoscientific model development · doi:10.5194/gmd-15-2973-2022 · Cited by 1,139
“10), whereby the ensemble spread encases the OSI SAF satellite observations (Lavergne et al., 2019).”
BackgroundNotz, D., & Community, S. (2020) · Geophysical Research Letters · doi:10.1029/2019gl086749 · Cited by 752
“For OSI SAF, we used the filled pole hole of the product itself.”
MethodSelf-citationAntarctic Sea Ice Area in CMIP6
Roach, L. A., Dörr, J. S., Holmes, C., Massonnet, F., Blockley, E., Notz, D., Rackow, T., Raphael, M., O’Farrell, S. P., Bailey, D. A., et al. (2020) · Geophysical Research Letters · doi:10.1029/2019gl086729 · Cited by 402
“To sample uncertainty in retrieval algorithms (Ivanova et al., 2014), we use three observational records of SIC: OSI SAF (Lavergne et al., 2019), NASA-Team (Cavalieri et al., 1997), and Bootstrap (Comiso et al., 1997).”
MethodSelf-citation
Metadata
- Authors
- Lavergne, T., Sørensen, A. M., Kern, S., Tonboe, R., Notz, D., Aaboe, S., Bell, L., Dybkjær, G., Eastwood, S., Gabarro, C., Heygster, G., Killie, M. A., Brandt Kreiner, M., Lavelle, J., Saldo, R., Sandven, S., & Pedersen, L. T.
- ORCID
- Venue
- The Cryosphere
- Publisher
- Copernicus GmbH
- Published
- 2019-01-09
- Volume
- 13
- Issue
- 1
- Pages
- 49-78
- ISSN
- 1994-0416 (ISSN-L)
- 1994-0424
- OpenAlex
- W2883803127
- Cited by
- 469
- References
- 65
- Citations by year
- 2026: 33 · 2025: 56 · 2024: 59 · 2023: 72 · 2022: 78 · 2021: 113 · 2020: 38 · 2019: 16
- FWCI
- 24.13
- Type
- journal article
- Language
- en
- Open access
- gold
- doi.org
- Licence
- Locations
- The cryosphere (publishedVersion, cc-by)
- DIGITAL.CSIC (Spanish National Research Council (CSIC)) (submittedVersion, cc-by)
- DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
- Technical University of Denmark, DTU Orbit (Technical University of Denmark, DTU) (submittedVersion, cc-by)
- Funders
- European Organization for the Exploitation of Meteorological Satellites
- Japan Aerospace Exploration Agency
- Topics
- Physical Sciences › Earth and Planetary Sciences › Atmospheric Science › Arctic and Antarctic ice dynamics
- Physical Sciences › Earth and Planetary Sciences › Atmospheric Science › Cryospheric studies and observations
- Physical Sciences › Earth and Planetary Sciences › Oceanography › Oceanographic and Atmospheric Processes
- Keywords
- sea ice concentration, climate data record, passive microwave remote sensing, satellite calibration, uncertainty estimation, SMMR, SSM/I, SSMIS, AMSR-E, AMSR2, 37 GHz, 6 GHz band, 19 GHz, horizontal resolution, Arctic sea ice, Antarctic sea ice
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
A language model drew the claims from the paper on 2026-10-16, under version 3 of the claim definition (model deepseek-v4.1-flash, prompt extract-v3).
A second model labelled each claim on 2026-10-16 (model jev-1.13-20260917, definition revision gold-guideline-v0.2).
Cited sources are checked with a language model’s help (gpt-6-sol).
Statistics and arithmetic are recomputed, not judged.
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