Ground solar absorption observations of total column CO, CO 2 , CH 4 , and aerosol optical depth from California's Sequoia Lightning Complex Fire: emission factors and modified combustion efficiency at regional scales

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Other column-based studies determined XCH4/XCO2 for urban sources in Los Angeles ranging from 6.65 to 9.96 ppb/ppm in 2015 and 11 ± 2 ‰ in 2008.

“Other column-based studies have determined the X CH 4 /X CO 2 for urban sources in the Los Angeles city, finding ratios ranging from 6.65 to 9.96 (ppb/ppm) in 2015 (Chen et al., 2016) and 11 ± 2 ‰ in 2008 (Wunch et al., 2009).”

• cites Chen et al., 2016 sourceSupported
• cites Wunch et al., 2009 sourceDisputed

  Table 1 (Summary and Conclusions) gives the xCH₄-to-xCO₂ anomaly slope as 7.8 ± 0.8‰, not 11 ± 2‰. The 11 ± 2‰ value belongs to xCO-to-xCO₂. This verdict concerns only the Wunch et al. value, not the separately cited 2015 range. (LLM, conf=0.90)

  Checked by a reasoning model — may be wrong.

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing).

Globally, about 10% of anthropogenic global CH4 is emitted by biomass burning.

“Globally, about 10 % of anthropogenic global CH 4 is emitted by biomass burning (Saunois et al., 2020) and may be an important and unaccounted for positive feedback to climate change, given the effect of increasing temperatures on fire severity.”

• cites Saunois et al., 2020 sourceDisputed

  The Biomass burning section (p. 16) estimates biomass-burning emissions at about 5% of global anthropogenic methane emissions in 2008–2017, not about 10%. The separate Biofuel burning section (p. 17) assigns biofuel burning another 3%; the cited paper does not assign their combined share to biomass burning alone. (LLM, conf=0.90)

  Checked by a reasoning model — may be wrong.

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Wildfires are a major source of air pollutants including particulate matter, carbon monoxide, and greenhouse gases primarily carbon dioxide and methane.

“Wildfires are a major source of air pollutants, including particulate matter (PM), carbon monoxide (CO), and greenhouse gases, primarily carbon dioxide (CO 2 ) and methane (CH 4 ; Akagi et al., 2011;Wiedinmyer et al., 2011;Andreae, 2019).”

• cites Akagi et al., 2011 sourceSupported
• cites Wiedinmyer et al., 2011 sourceNot checked — no full text of the source
• cites Andreae, 2019 sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The EM27/SUN is a ground-based remote sensing instrument that is relatively portable and robust for field deployments.

“The EM27/SUN is a ground-based remote sensing instrument that is relatively portable and robust for field deployments (Chen et al., 2016;Heerah et al., 2021).”

• cites Chen et al., 2016 sourceSupported
• cites Heerah et al., 2021 sourcePartly supported

  Section 2.2 (page unavailable) calls the EM27/SUN a “compact field deployable” spectrometer and reports its use during summer and winter field campaigns, supporting the ground-based and relatively portable parts of the claim. It does not describe the instrument as robust or assess its durability in field conditions. (LLM, conf=0.82)

  Experimental — accuracy not yet measured

May combine two claims.

Column measurements are insensitive to planetary boundary layer growth and are less affected by nearby point sources than in situ measurements, making them a good candidate for regional-scale monitoring.

“Column measurements are insensitive to the planetary boundary layer growth and are less affected by nearby point sources than in situ measurements, making them a good candidate for regional-scale monitoring (Lindenmaier et al., 2014).”

• cites Lindenmaier et al., 2014 sourcePartly supported

  The SI Text (p. 2) says column observations detected regionally elevated CO2 over strong, extended source regions when averaged across several years, offering limited support for regional-scale use. The retrieved passages do not say that column measurements are insensitive to planetary boundary layer growth or less affected by nearby point sources than in situ measurements. (LLM, conf=0.77)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

AERONET stations are frequently calibrated and set the standard for aerosol measurements and validation for satellite products.

“The stations are frequently calibrated, and they set the standard for aerosol measurements and validation for satellite products (Giles et al., 2019).”

• cites Giles et al., 2019 sourceSupported

May combine two claims.

Urban fossil fuel and wildfire XCH4/XCO2 ratios are very similar due to incomplete combustion and are not distinct enough to separate.

“Wunch et al. (2009) determined that urban fossil fuel and wildfire X CH 4 /X CO 2 ratios are very similar due to incomplete combustion, and the ratios are not distinct enough to separate.”

• cites Wunch et al., 2009 sourceCould not verify

  The Methods (§2, paragraph 10; page unavailable) say wildfire-affected days were excluded because they had large CO contributions. The Introduction (§1, paragraph 2; page unavailable) links incomplete combustion to CO, not to an XCH4/XCO2 ratio. Searches for wildfire–fossil-fuel ratio comparisons found no passage saying their XCH4/XCO2 ratios are similar or cannot distinguish the sources. (LLM, conf=0.76)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing).

Unless instruments are secured properly, measurements require personnel to set up and operate the instrument daily.

“Unless instruments are secured properly, as has been done in long-term FTIR network studies (Frey et al., 2019;Dietrich et al., 2021), measurements require personnel to set up and operate the instrument daily.”

• cites Frey et al., 2019 sourceSupported
• cites Dietrich et al., 2021 sourceSupported

May combine two claims.

In California, statewide wildfire estimates of CO2 and PM are based on FOFEM, though reports of CH4 estimates from wildfires are lacking.

“In California, statewide wildfire estimates of CO 2 and PM are based on the USA Forest Service's First Order Fire Effects Model (FOFEM; Reinhardt and Dickinson, 2010), though reports of CH 4 estimates from wildfires are lacking, despite the importance of CH 4 for meeting the state's ambitious climate goals.”

• cites Reinhardt and Dickinson, 2010 sourcePartly supported

  The Conclusions table identifies FOFEM as a system used for smoke-production modeling, supporting the identification of the model. The paper does not say that California’s statewide CO2 and PM wildfire estimates are based on FOFEM, or that reports of wildfire CH4 estimates are lacking (searched: California statewide estimates, CO2, PM, and CH4). (LLM, conf=0.82)

  Experimental — accuracy not yet measured

May combine two claims.

Prichard et al. (2020) found a fire average for North American conifer forests of EFCO2 1629.54 ± 63.43, EFCO 104.01 ± 34.93, and EFCH4 5.05 ± 2.41.

“Additionally, our calculated emission factors also agree well with recently compiled emission factors for North American conifer forests, where Prichard et al. (2020) found a fire average for EF CO 2 of 1629.54 ± 63.43, EF CO of 104.01 ± 34.93, and EF CH 4 of 5.05 ± 2.41.”

• cites Prichard et al., 2020 sourcePartly supported

  Table 5 (shown in the Sample calculations section; page unavailable) gives exactly these fire-average means and standard deviations for CO₂, CO and CH₄. The table labels the figures as applying to western US conifer forests (western pine and mixed conifer), not North American conifer forests as a whole. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

May combine two claims.

Empirically quantified EFs in temperate conifer forests are limited in number, and many measurements in these regions are from prescribed burning for land management.

“Empirically quantified EFs in temperate conifer forests are limited in number, and many of the measurements in these regions are from prescribed burning for land management (Burling et al., 2011;Akagi et al., 2011;Urbanski, 2013).”

• cites Burling et al., 2011 sourceSupported
• cites Akagi et al., 2011 sourceSupported
• cites Urbanski, 2013Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

Barreto et al. (2020) carefully selected and evaluated several FTIR micro-windows to minimize gas absorption; thus, τg,λ is considered negligible.

“Barreto et al. (2020) carefully selected and evaluated several FTIR micro-windows to minimize the gas absorption; thus, τ g, λ is considered negligible.”

• cites Barreto et al. (2020) sourceSupported

Classified as probably not a substantial claim.

An averaging kernel correction has been applied to the EM27/SUN observations prior to comparison, following Hedelius et al. (2016).

“An averaging kernel correction has been applied to the EM27/SUN observations prior to comparison, following Hedelius et al. (2016).”

• cites Hedelius et al. (2016) sourceSupported

Classified as probably not a substantial claim.

Barreto et al. (2020) found good agreement between AERONET and TCCON FTIR-derived AOD at the high-altitude Izaña Atmospheric Observatory in Spain.

“To calculate AOD from the EM27/SUN solar measurements, we follow the methods described in Barreto et al. (2020), who found good agreement between AERONET and TC-CON FTIR-derived AOD at the high-altitude Izaña Atmospheric Observatory in Spain.”

• cites Barreto et al. (2020) sourceSupported

May combine two claims.

An estimated 213.7 ± 49.8 Gg CH4 were emitted by large wildfires in California during 2020, about 13.7 % of the total state CH4 emissions in 2020.

“Finally, we put wildfire CH 4 emissions in context of the California state CH 4 budget and estimate that 213.7±49.8Gg CH 4 were emitted by large wildfires in California during 2020, about 13.7 % of the total state CH 4 emissions in 2020.”

May combine two claims.

Total column EF CO is 120.5 ± 12.2 and EF CH4 is 4.3 ± 0.8 for a regional smoke plume event in mixed combustion phases.

“These observations are used to derive total column EF CO of 120.5 ± 12.2 and EF CH 4 of 4.3 ± 0.8 for a regional smoke plume event in mixed combustion phases.”

• Also stated in: § 3.3 Emission factors and modified combustion efficiency · plain

  “ER CO was 0.1161 ± 0.0005, and the ER CH 4 was 0.00730 ± 0.00007, resulting in an EF CO 2 of 1632.9±163.3g CO 2 kg -1 biomass combusted, EF CO of 120.5 ± 12.2 g CO kg -1 biomass combusted, and EF CH 4 of 4.3±0.8g CH 4 kg -1 biomass combusted.”

• AssumptionThe authors state this as an assumption: 500 ± 50 g of carbon is emitted per kilogram of dry biomass consumed.

May combine two claims.

A regional smoke plume captured by NOAA-20 VIIRS on 12 September originated from the SQF Complex and traveled west directly over the measurement site.

“A regional smoke plume was captured by the NOAA-20 VIIRS satellite on 12 September that originated from the SQF Complex and traveled west directly over the measurement site, as seen in Fig. 1b.”

May combine two claims.

High-altitude smoke can be transported large distances, corroborated by ash falling at a site about 60 km from the fire and by satellite imagery.

“Highaltitude smoke can be transported large distances, corroborated by observations of ash falling from the sky at a measurement site ∼ 60 km away from the fire and clearly observable by satellite imagery (Fig. 1b).”

May combine two claims.

X CO, X CO2, and X CH4 averaged 154 ± 78 ppb, 413 ± 1 ppm, and 1938 ± 27 ppb from 8 September to 17 October.

“X CO , X CO 2 , and X CH 4 averaged at 154±78 ppb, 413±1 ppm, and 1938±27 ppb from 8 September to 17 October.”

May combine two claims.

The FTIR AOD follows the same inter-day trend as AERONET AOD, with a peak on 12 September, although the sites are about 90 km apart and smoke reaching them varied over these spatial scales.

“The observational sites were relatively far from each other (∼ 90 km), and although smoke reaching the two sites varied over these spatial scales, the FTIR AOD follows the same inter-day trend as the AOD measured by the AERONET, with a peak in AOD on 12 September.”

May combine two claims.

X CO and X CO2 peaked on 12 September at 1012.8 ppb and 421.6 ppm, while X CH4 peaked on 28 September at 2050.1 ppb due to dairy farms in the area.

“X CO and X CO 2 peaked on 12 September at 1012.8 ppb and 421.6 ppm, while X CH 4 peaked on 28 September at 2050.1 ppb due to the dairy farms in the area.”

May combine two claims.

X CO2 and X CH4 were enhanced on the 12 September smoke event and followed the same trend as X CO over the course of the day.

“X CO 2 and X CH 4 were also enhanced on the 12 September smoke event and followed the same trend as X CO over the course of the day.”

May combine two claims.

In the vicinity of the measurement site in the SJV, there is a strong influence of dairy farm agriculture and minimal urban emissions away from population centers.

“In the vicinity of the measurement site in the SJV, there is a strong influence of dairy farm agriculture and minimal urban emissions away from population centers; thus, we are able to separate X CH 4 / X CO 2 from dairy sources, from fire, or from possible urban emissions.”

May combine two claims.

ER CO was 0.1161 ± 0.0005 and ER CH4 was 0.00730 ± 0.00007 on 12 September.

“ER CO was 0.1161 ± 0.0005, and the ER CH 4 was 0.00730 ± 0.00007, resulting in an EF CO 2 of 1632.9±163.3g CO 2 kg -1 biomass combusted, EF CO of 120.5 ± 12.2 g CO kg -1 biomass combusted, and EF CH 4 of 4.3±0.8g CH 4 kg -1 biomass combusted.”

May combine two claims.

The 12 September smoke plume event had a smaller emission ratio of 7.3 ± 0.07 ppb/ppm compared to larger XCH4/XCO2 enhancement ratios of 38.4 ± 21.7 and 30.5 ± 5.0 ppb/ppm observed in September 2018 and 2019.

“The 12 September smoke plume event is highlighted in Fig. 7 (red markers) and has a smaller emission ratio of 7.3 ± 0.07 (ppb/ppm) compared to larger X CH 4 / X CO 2 enhancement ratios of 38.4 ± 21.7 and 30.5 ± 5.0 (ppb/ppm) observed in September 2018 and 2019.”

May combine two claims.

The monthly background in September was 411.3 ppm for X CO2, 99.4 ppb for X CO, and 1905.3 ppb for X CH4.

“The monthly background in September was 411.3 ppm (parts per million) for X CO 2 , 99.4 ppb for X CO , and 1905.3 ppb for X CH 4 .”

May combine two claims.

Strong relationships (R2 > 0.61) were found between EM27/SUN X CO and AOD at 500 nm, with slopes ranging from 29.01 to 92.41 ppb/AOD.

“We find strong relationships (R 2 > 0.61) between the EM27/SUN X CO and AOD at 500 nm, with slopes ranging from 29.01 to 92.41 ppb/AOD (Table 1 and Fig. 3).”

May combine two claims.

Enhancements of AOD were observed throughout the first week of measurements, with the highest recorded AOD on 12 September.

“Similar to observations of X CO , enhancements of AOD are observed throughout the week, with the highest recorded AOD on 12 September.”

May combine two claims.

Selecting a 15 km maximum radius with a 30 min averaging time gives 19 coincident data points, a mean difference of 17.2 ppb, a mean relative difference of 9.7 ± 1.3 %, and R2 of 0.97.

“This gives a total of 19 coincident data points and a mean difference of 17.2 ppb, a mean relative difference of 9.7 ± 1.3 %, and R 2 of 0.97.”

May combine two claims.

During September-October 2020 observations, XCH4/XCO2 ratios of dairy farm influence were found on several days, in addition to lower slopes indicative of combustion sources.

“During September-October 2020 observations, X CH 4 / X CO 2 ratios of dairy farm influence were found on several days, in addition to lower slopes indicative of Figure 6.Emission factors (g kg -1 ) for (a) CH 4 and (b) CO as a function of MCE for temperate coniferous forests from Sierra Nevada wildfires.”

The quote only partly states this claim.

The average ERCH4 for Sierra Nevada wildfires is 0.0084 ± 0.0022.

“We then used Eq. ( 2) to solve for ER CH 4 with C T equal to 1 (ER CH 4 _avg = 0.0084 ± 0.0022).”

May combine two claims.

The XCO enhancement from the 2020 wildfires in the Sierra Nevada was observed from space, and in concentrated smoke plumes, XCO was up to 10 times higher than local background during the 12 September smoke plume event.

“The X CO enhancement from the 2020 wildfires in the Sierra Nevada was also observed from space, and in concentrated smoke plumes, X CO was up to 10 times higher than the local background, which was clearly visible in the TROPOMI soundings during the 12 September smoke plume event.”

May combine two claims.

FTIR-derived AOD at 500 nm reached extremely high levels during the 12 September smoke plume event and followed the same trend on other days as the trace gas enhancements.

“FTIR-derived AOD at 500 nm reached extremely high levels during the 12 September smoke plume event and followed the same trend on other days as the trace gas enhancements.”

May combine two claims.

The FTIR-derived AOD showed the same baseline pattern as the AERONET site in Fresno, demonstrating the ability of the EM27/SUN to simultaneously measure AOD and trace gases through a thick plume of smoke.

“However, the FTIR-derived AOD showed the same baseline pattern as the AERONET site in Fresno, demonstrating the ability of the EM27/SUN to simultaneously measure AOD and trace gases through a thick plume of smoke, which can elucidate mechanisms within smoke plumes.”

May combine two claims.

Mirror degradation and exposure to dust or ash from fires can be observed in a declining ln(Vo), and a sudden jump in ln(Vo) is observed in late October and early November after the mirrors were cleaned, suggesting debris had diminished the solar intensity measured by the FTIR instrument.

“Mirror degradation and exposure to dust or ash from fires can be observed in a declining ln(V o ), and a sudden jump in ln(V o ) is observed in late October and early November after the mirrors were cleaned, suggesting that debris had diminished the solar intensity measured by the FTIR instrument.”

May combine two claims.

Without applying the averaging kernel correction, ECH4 would be underestimated by 9.5% and ECO by 14.2% due to difference in sensitivity.

“Without applying this correction, E CH 4 would be underestimated by 9.5 % and E CO by 14.2 % due to the difference in sensitivity.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

Wildfire smoke produced overcast skies throughout the western USA during this period, with smoke plumes being transported over long distances.

“Wildfire smoke produced overcast skies throughout the western USA during this period, with smoke plumes being transported over long distances.”

May combine two claims.

The 20 largest wildfires of 2020 emitted 13.7% of total state anthropogenic CH4 emissions, which is more than the commercial and residential, transportation, and electric power sectors.

“These wildfires alone emitted 13.7 % of the total state anthropogenic CH 4 emissions, which is more than the commercial and residential, transportation, and electric power sectors.”

May combine two claims.

The mean relative difference in the correction for the 12 September plume event is -1.1%; not applying this correction would overestimate MCE by 1.1%.

“The mean relative difference in the correction for the 12 September plume event is -1.1 %; thus, not applying this correction would overestimate the MCE by 1.1 %.”

May combine two claims. The quote only partly states this claim.

AOD was derived from micro-windows within the first detector, so AOD calculations were not affected by the camera misalignment.

“AOD was derived from micro-windows within the first detector; thus, calculations of AOD were not affected.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The majority of the TROPOMI X CH4 product was flagged out near the observational site during the measurement period and was not included in the analysis.

“The majority of the TROPOMI X CH 4 product was flagged out near the observational site during our measurement period and hence was not included in this analysis.”

Classified as probably not a substantial claim.

Measurement uncertainties for the EFs were calculated by propagating the error from the ER linear regression standard error, C T, and 10 % error from M Biomass.

“The measurement uncertainties for the EFs were calculated by propagating the error from the ER linear regression standard error, C T , and 10 % error from M Biomass .”

• AssumptionThe authors state this as an assumption: 500 ± 50 g of carbon is emitted per kilogram of dry biomass consumed.

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Co-locating the EM27/SUN and TCCON instruments ensures system stability of the EM27/SUN after transportation to field sites.

“Co-locating the EM27/SUN and TC-CON instruments ensures system stability of the EM27/SUN after transportation to field sites.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Monthly average mixing ratios measured in situ at Mauna Loa for CO2 were 411.5 ± 0.2 ppm and CH4 1884.7 ± 1 ppb during September 2020.

“The monthly average mixing ratios measured in situ at Mauna Loa for CO 2 were 411.5±0.2 ppm and CH 4 1884.7± 1 ppb during September 2020 (https://gml.noaa.gov/obop/ mlo/, last access: 15 April 2022).”

• cites https://gml.noaa.gov/obop/ mlo/Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

Ground-based solar spectrometers present an alternative technique to measure and understand fire emissions at regional scales and temporally complement satellite observations.

“Ground-based solar spectrometers present an alternative technique to measure and understand fire emissions at regional scales and temporally complement satellite observations.”

Probably not a substantial claim: may not pass S3 (load-bearing).

The York linear regression considers instrument errors along both axes.

“The York linear regression considers the instrument errors along both axes.”

May combine two claims.

The EM27/SUN provides vertically integrated column measurements of CH4, CO2, and CO, which allows calculation of modified combustion efficiency and emission factors in the total column of smoke plumes downwind of wildfires.

“The EM27/SUN provides vertically integrated column measurements of CH 4 , CO 2 , and CO, which allows for the calculation of the modified combustion efficiency (MCE) and emission factors (EFs) in the total column of smoke plumes downwind of wildfires.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

The measured X CO on 12 September is the highest reported X CO value in the EM27/SUN literature.

“The measured X CO on 12 September is the highest reported X CO value in the EM27/SUN literature.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Retrievals of X gas using the EM27/SUN in such dense smoke plumes have not been reported in previous studies.

“Retrievals of X gas , using the EM27/SUN in such dense smoke plumes, has not been reported in previous studies.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

Exposing the instrument's mirrors to harsh conditions such as ash decreases the instrument signal and may decrease the lifetime of the mirrors.

“Exposing the instrument's mirrors to harsh conditions such as ash decreases the instrument signal and may decrease the lifetime of the mirrors.”

May combine two claims.

CARB reported a total of 106.7 Tg of CO2 emitted from 2020 wildfires and individual CO2 emission estimates for the 20 largest wildfires of 2020.

“The California Air Resources Board (CARB) reported that a total of 106.7 Tg of CO 2 was emitted from 2020 wildfires and reported individual CO 2 emission estimates for the 20 largest wildfires of 2020.”

• cites CARBNot matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

The majority of the TROPOMI XCH4 product was flagged out completely near the observational site during the 7-15 September period and was not included in this analysis.

“For example, the majority of the TROPOMI X CH 4 product was flagged out completely near the observational site during the 7-15 September period and hence was not included in this analysis.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Rowe et al. (2022) found that multiple scattering on aerosols may be responsible for 5%-10% of increased XCO observations from TROPOMI in thick smoke plumes.

“Alternatively, Rowe et al. (2022) found that multiple scattering on aerosols may be responsible for 5 %-10 % of the increased X CO observations from TROPOMI in thick smoke plumes.”

• cites Rowe et al., 2022 sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

EM27/SUN instruments are costly, which can limit the number of instruments deployed.

“EM27/SUN instruments are also costly, which can limit the number of instruments deployed.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Jacobs (2021) found that wildfire influences in XCO resulted in high observational variance in EM27/SUN observations and suggested this may be due to spatial and temporal variability in the smoke plume measured by TROPOMI and EM27/SUN.

“Jacobs (2021) found that wildfire influences in X CO resulted in a high observational variance in EM27/SUN observations and suggested that this may be due to spatial and temporal variability in the smoke plume measured by TROPOMI and the EM27/SUN.”

• cites Jacobs, 2021Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

Fires in California fell into temperate forest, shrubland or grassland vegetation types.

“Emission ratios from fires are dependent on vegetation type; fires in California fell into temperate forest, shrubland or grassland vegetation types (Xu et al., 2022).”

• cites Xu et al., 2022Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Scattered diffuse light during high aerosol loading from biomass burning may decrease the reliability of AOD observations, so further verification of FTIR-derived AOD during high aerosol loading is required.

“Scattered diffuse light during high aerosol loading from biomass burning may decrease the reliability of the AOD observations; thus, further verification of the FTIRderived AOD during high aerosol loading is required.”

Probably not a substantial claim: may not pass S3 (load-bearing).

EM27/SUN observations can be used as a validation tool for orbiting satellites like TROPOMI, OCO-2, OCO-3, and future satellites.

“Furthermore, the EM27/SUN observations can be used as a validation tool for orbiting satellites like TROPOMI, the Orbiting Carbon Observatory-2 (OCO-2), OCO-3, and future satellites.”

Probably not a substantial claim: may not pass S3 (load-bearing).

The mean relative difference between EM27/SUN and TROPOMI may be due to averaging of smoke plume heterogeneity within each TROPOMI comparison point.

“The 9.7 ± 1.3 % mean relative difference between the EM27/SUN and TROPOMI found in this study may also be due to the averaging of the smoke plume's heterogeneity within each TROPOMI comparison point.”

May combine two claims.

The FTIR is limited to the line of sight of the instrument and on occasion can miss the plume, as happened on 13 and 14 September.

“Although total column measurements are sensitive to larger scales than in situ stations, the FTIR is limited to the line of sight of the instrument and on occasion can miss the plume, like we did on 13 and 14 September, whereas aircraft observations have extensive spatial reach and more flexibility in locating and sampling plumes to obtain spatially rich information of the plume.”

Probably not a substantial claim: may not pass S3 (load-bearing).

AOD at the AERONET site in Fresno increased by 3 to 5 times in the yearly average from 2002-2019.

“The air quality index in the SJV was at an all-time high in the hazardous range for weeks during the 2020 wildfire season (Morris and Dennis, 2020), and AOD at the AERONET site in Fresno, the yearly average from 2002-2019 increased by 3 to 5 times (Cho et al., 2022).”

• cites Cho et al., 2022Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing).

The air quality index in the SJV was at an all-time high in the hazardous range for weeks during the 2020 wildfire season.

“The air quality index in the SJV was at an all-time high in the hazardous range for weeks during the 2020 wildfire season (Morris and Dennis, 2020), and AOD at the AERONET site in Fresno, the yearly average from 2002-2019 increased by 3 to 5 times (Cho et al., 2022).”

• cites Morris and Dennis, 2020Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

The nearest AERONET station was relatively far away from the EM27/SUN site, so a true side-by-side comparison cannot be done.

“Since the nearest AERONET station was relatively far away from our EM27/SUN site, we cannot do a true side-by-side comparison.”

Probably not a substantial claim: may not pass S4 (based).

Stationary, ground-based instruments are limited to observing a line of sight or point in space.

“Conversely, stationary, ground-based instruments are limited to observing a line of sight or point in space.”

May combine two claims.

The EFs, MCE, and their uncertainties fall within the range of expected values, lending confidence that this technique can be used for studying combustion phases of wildfires for other vegetation types.

“The EFs, MCE, and their uncertainties fall within the range of expected values, thus lending confidence that this technique can be used for studying combustion phases of wildfires for other vegetation types.”

May combine two claims.

The EM27/SUN measured continuously in the daytime, filling in temporal gaps from TROPOMI's single overpass observations.

“The EM27/SUN measured continuously in the daytime, filling in the temporal gaps from the satellite TROPOMI's single overpass observations.”

May combine two claims.

The EM27/SUN measures a vertically integrated regional signal but is limited spatially compared to observations from satellites.

“The EM27/SUN measures a vertically integrated regional signal but is limited spatially compared to observations from satellites.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Due to a camera misalignment on 2 and 3 September, XCO correction factors for those dates are not reported.

“Due to a camera misalignment on 2 and 3 September, X CO correction factors for those dates are not reported.”

Probably not a substantial claim: may not pass S3 (load-bearing).

A cloud filter is applied to the spectra based on measured fractional variation in solar intensity, set to a maximum of 0.5% variability to ensure minimum cloud interference.

“A cloud filter is applied to the spectra based on the measured fractional variation in solar intensity (fvsi).We set this quality filter to a maximum of 0.5 % variability to ensure minimum cloud interference.”

May combine two claims.

This agreement is consistent with systematic differences between TCCON and TROPOMI, in addition to previous studies of EM27/SUN XCO for wildfires in rural Alaska and Idaho.

“This is consistent with systematic differences between TCCON and TROPOMI, in addition to previous studies of EM27/SUN X CO for wildfires in rural Alaska and Idaho.”

Classified as probably not a substantial claim.

The EM27/SUN was co-located with the CIT TCCON for 2-3 days before and after the field measurements.

“The EM27/SUN was co-located with the CIT TCCON for 2-3 d before (2 and 3 September 2020) and after (30 and 31 October and 1 November 2020) the field measurements.”

May combine two claims.

Wildfires are an important source of CH4 for California and may delay meeting the state's ambitious goals for reducing greenhouse gas emissions.

“Given the importance of the CH 4 emissions reduction for the state, our study suggests that wildfires are an important source of CH 4 for California and may delay the meeting of the state's ambitious goals for reducing greenhouse gas emissions.”

Classified as probably not a substantial claim.

Due to varying ln(Vo), AOD is calculated only for the first week of data collection (8-15 September), using ln(Vo) obtained during the earlier period of September.

“Due to the varying ln(V o ), we calculate AOD only for the first week of data collection (8-15 September), using the ln(V o ) obtained during the earlier period of September (summarized in Table B1).”

May combine two claims.

The portable nature of the EM27/SUN allows for deployment downwind of fires and for calculating important variables like EFs and MCE.

“The portable nature of the EM27/SUN allows for deployment downwind of fires and for calculating important variables like EFs and MCE.”