Cassini imaging of Saturn: Southern hemisphere winds and vortices

No direct analogs to the northern hemisphere's polar hexagon or ribbon waves were observed in Saturn's southern hemisphere.

“but no direct analogs to the northern hemisphere's polar hexagon or ribbon waves were observed”

Nonequatorial wind measurements from Cassini images (February to October 2004) display only minor differences from measurements collected since 1981.

“Nonequatorial wind measurements display only minor differences from those collected since 1981”

• AssumptionRests on an assumption: Cloud features tracked in the images move with the ambient zonal wind (i.e., are passive tracers).

The two eastward jets nearest the pole display periodicity in their longitudinal structure.

“The two eastward jets nearest the pole display periodicity in their longitudinal structure”

Cassini wind measurements reveal a strong, prograde flow near the pole.

“reveal a strong, prograde flow near the pole”

• Also stated in: § 3. Appearance and Zonal Winds · plain

  “Poleward of that latitude, measurements are all positive (eastward), but vary between 0 and 140 m s À1 .”

• AssumptionRests on an assumption: Cloud features tracked in the images move with the ambient zonal wind (i.e., are passive tracers).

The eastward jet near 60.5°S is 35 m/s faster during the Cassini era than in Voyager/HST measurements.

“The eastward jet near 49.5°S is $20 m s À1 slower during the Cassini era, while the eastward jet near 60.5°S is 35 m s À1 faster.”

• AssumptionRests on an assumption: Cloud features tracked in the images move with the ambient zonal wind (i.e., are passive tracers).

The eastward jet near 49.5°S is approximately 20 m/s slower during the Cassini era than in Voyager/HST measurements.

“The eastward jet near 49.5°S is $20 m s À1 slower during the Cassini era, while the eastward jet near 60.5°S is 35 m s À1 faster.”

• AssumptionRests on an assumption: Cloud features tracked in the images move with the ambient zonal wind (i.e., are passive tracers).

The polar wind measurements exhibit little dispersion equatorward of approximately 84°S.

“The polar wind measurements (Figure 4) exhibit little dispersion equatorward of $84°S.”

• AssumptionRests on an assumption: Cloud features tracked in the images move with the ambient zonal wind (i.e., are passive tracers).

The pole itself is a dark spot surrounded by a ring of bright cloud material at 88.8°S.

“The pole itself is a dark spot surrounded by a ring of bright cloud material at 88.8°S.”

The final AMs contain only approximately 65 vortices, compared to 138 in the HRMs.

“Even the final AMs contain only $65 vortices, compared to 138 in the HRMs.”

The polygonal structure in the 60.5°S dark band pair is ephemeral; images acquired several days before and after the HRM do not show the same pattern.

“The structure is ephemeral; images acquired several days before and after the HRM do not show the same pattern.”

The 38.5°S-46°S region is associated with active but short-lived (days to weeks) convective outbursts.

“This region is also associated with active but short-lived (days to weeks) convective outbursts, such as the bright storm seen in Figure 3 and described by Porco et al. [2005].”

Vortex-related cloud filaments and patchy bright clouds fill the area between vortices in the 38.5°S-46°S region.

“Vortex-related cloud filaments and patchy bright clouds fill the area between vortices.”

When MT images are viewed at full spatial resolution, the bands contain extended cloud filaments that bend and fold due to interactions between jets, or between jets and vortices.

“However, when MT images are viewed at full spatial resolution, the bands are found to contain extended cloud filaments that bend and fold due to interactions between jets, or between jets and vortices.”

The region between 29.5°S and 33°S contains a set of peculiar features, quasiperiodic in longitude and extending around the planet.

“The region between 29.5°S and 33°S contains a set of peculiar features, quasiperiodic in longitude and extending around the planet.”

The CB2 map contains more fine-scale structure than the other wavelength maps, such as internal structure of larger vortices, smaller vortices and patchy clouds, and the convective storm and its associated clouds.

“The CB2 map contains more fine-scale structure than the others in Figures 5a and 5b, such as the internal structure of larger vortices, the presence smaller vortices and patchy clouds, and the convective storm and its associated clouds.”

Tilted cloud streaks are present from 33°S to 38.5°S.

“Tilted cloud streaks are present from 33°S to 38.5°S.”

In general, there are no major features (e.g., vortices) that are unique to the higher-sounding wavelengths.

“In general, there are no major features (e.g., vortices) that are unique to the higher-sounding wavelengths.”

Narrow bands with less cloud/haze scattering occur just southward (on the cyclonic sides) of the eastward jet maxima at 49.5°S, 60.5°S, and 74.5°S.

“Figures 5a and 5b show that narrow bands with less cloud/haze scattering occur just southward (i.e., on the cyclonic sides) of the eastward jet maxima at 49.5°S, 60.5°S, and 74.5°S.”

The size frequency distributions suggest that the population of vortices with east-west diameters <1000 km cannot accurately be counted in the final AM.

“The size frequency distributions in Figure 6 suggest that the population of vortices with east-west diameters <1000 km cannot accurately be counted in the final AM.”

A pattern of tilted cloud streaks covers latitudes between 10°S and 29.5°S, revealing the strong latitudinal shear in the zonal winds.

“A pattern of tilted cloud streaks covers latitudes between 10°S and 29.5°S, revealing the strong latitudinal shear in the zonal winds.”

The region between 38.5°S and 46°S, the peak and poleward side of the broad westward jet centered near 41°S, is distinguished by an abundance of vortices.

“The region between 38.5°S and 46°S, the peak and poleward side of the broad westward jet centered near 41°S, is distinguished by an abundance of vortices.”

The regions between the dark band pairs (including another near the eastward jet at 74.5°S) are relatively wider bands containing vortices and patchy bright clouds.

“The regions between these dark band pairs (including another near the eastward jet at 74.5°S) are relatively wider bands containing vortices and patchy bright clouds.”

Cloud morphologies in the HRM of Saturn's southern hemisphere resemble the Voyager and HST descriptions of zonal bands, discrete clouds, vortices, and convective storms.

“Cloud morphologies in the HRM of Saturn's southern hemisphere (Figures 1 and 2) resemble the Voyager and HST descriptions of zonal bands, discrete clouds, vortices, and convective storms.”

A pair of dark bands straddles each of the eastward jets near 49.5°S and 60.5°S.

“A pair of dark bands straddles each of the eastward jets near 49.5°S and 60.5°S.”

Tracking the asymmetric bright ring that surrounds the pole at 88.8°S provided very high-latitude measurements that fall between 80 and 135 m/s.

“Tracking the asymmetric bright ring that surrounds the pole at 88.8°S provided a set of very high-latitude measurements that fall between 80 to 135 m s À1 .”

• AssumptionRests on an assumption: Cloud features tracked in the images move with the ambient zonal wind (i.e., are passive tracers).

The south polar map indicates no obvious southern analog to the north polar hexagon near 78.5°N.

“The south polar map (Figure 2) indicates no obvious southern analog to the north polar hexagon near 78.5°N [Allison et al., 1990;Sa ´nchez-Lavega et al., 2002].”

Vortices are clustered in latitude.

“Vortices are clustered in latitude but are present in regions of both cyclonic and anticyclonic shear in the zonal wind.”

Dark vortices with bright margins are larger than dark vortices.

“Dark vortices with bright margins are larger than dark vortices, but occur in some of the same latitude bands.”

Other unclassified vortices include two at 76.4°S that are difficult to differentiate from the ubiquitous patchy clouds.

“Other unclassified vortices include two at 76.4°S that are difficult to differentiate from the ubiquitous patchy clouds, and two bright vortices with unique morphologies at (41.1°S, 344.3°W) and (39.2°S, 57.4°W) in the HRM.”

There are several vortices covering a wide range of sizes in regions of cyclonic shear.

“Although their frequency is greater within regions of anticyclonic shear, there are several vortices covering a wide range of sizes in regions of cyclonic shear.”

Vortices are present in regions of both cyclonic and anticyclonic shear in the zonal wind.

“Vortices are clustered in latitude but are present in regions of both cyclonic and anticyclonic shear in the zonal wind.”

Six vortices did not easily fit into the four families.

“Six vortices did not easily fit into the above families.”

Dark vortices occur in several latitude bands.

“Dark vortices are small, round, numerous, and occur in several latitude bands.”

Dark vortices with bright margins occur only in anticyclonic regions.

“Dark vortices with bright margins occur only in anticyclonic regions.”

Bright-centered vortices are moderately sized.

“Bright-centered vortices are moderately sized and occur in two latitude bands.”

The two broad regions in between these eastward jets are relatively uniform in brightness, despite the change in sign of vorticity across the westward jet.

“The two broad regions in between these eastward jets are relatively uniform in brightness, despite the change in sign of vorticity across the westward jet.”

Vortex frequency is greater within regions of anticyclonic shear.

“Although their frequency is greater within regions of anticyclonic shear, there are several vortices covering a wide range of sizes in regions of cyclonic shear.”

The two bright vortices share the same latitude band.

“There are only two bright vortices, sharing the same latitude band.”

Other unclassified vortices include two bright vortices with unique morphologies at (41.1°S, 344.3°W) and (39.2°S, 57.4°W) in the HRM.

“Other unclassified vortices include two at 76.4°S that are difficult to differentiate from the ubiquitous patchy clouds, and two bright vortices with unique morphologies at (41.1°S, 344.3°W) and (39.2°S, 57.4°W) in the HRM.”

Dark vortices are present in both anticyclonic and cyclonic regions.

“Dark vortices are present in both anticyclonic and cyclonic regions.”

There are only two bright vortices.

“There are only two bright vortices, sharing the same latitude band.”

Dark vortices are round.

“Dark vortices are small, round, numerous, and occur in several latitude bands.”

Dark vortices are numerous.

“Dark vortices are small, round, numerous, and occur in several latitude bands.”

Dark vortices are small.

“Dark vortices are small, round, numerous, and occur in several latitude bands.”

All but one of the bright-centered vortices are in cyclonic regions.

“All but one of the bright-centered vortices are in cyclonic regions, and the exception at 73.5°S does not have the same shape as the others, suggesting that it may be unique.”

The exception bright-centered vortex at 73.5°S does not have the same shape as the others.

“All but one of the bright-centered vortices are in cyclonic regions, and the exception at 73.5°S does not have the same shape as the others, suggesting that it may be unique.”

Bright-centered vortices occur in two latitude bands.

“Bright-centered vortices are moderately sized and occur in two latitude bands.”

Several bright-centered vortices have north-south diameters exceeding their east-west diameters.

“Several brightcentered vortices have the unusual property that their north-south diameters exceed their east-west diameters (see Figure 2).”

The greatest concentrations of vortices occur near the westward jets.

“The greatest concentrations of vortices occur near the westward jets, as observed on Jupiter [Li et al., 2004].”

• cites Li et al., 2004Not checked yet

  Not checked in the free run.

Dark vortices with bright margins occur in some of the same latitude bands as dark vortices.

“Dark vortices with bright margins are larger than dark vortices, but occur in some of the same latitude bands.”

The largest vortex observed, at 51.8°S, is in a cyclonic region.

“Both of the bright vortices are in a cyclonic region, while the largest vortex we observe (at 51.8°S) is in a cyclonic region.”

Vortices were observed to drift with both eastward and westward velocities relative to System III.

“Vortices were observed to drift with both eastward and westward velocities relative to System III.”

The region with the most vortex activity, storm alley, violates the barotropic stability criterion the least.

“Vortices are present near each of these locations where the criterion is violated, but the region with the most activity (''storm alley'') violates the criterion the least.”

In all cases the instantaneous vortex drift rate was indistinguishable from the zonal wind speed at the latitude corresponding to the vortex center.

“In all cases the instantaneous drift rate was indistinguishable from the zonal wind speed at the latitude corresponding to the vortex center.”

• AssumptionRests on an assumption: The measured zonal wind profile at cloud level represents the ambient wind at the vortex latitudes.

The largest vortex drifted steadily at 50 ± 5 m s−1 during the AM.

“The largest vortex in our study sits alone in its latitude band at 51.8°S and drifted steadily at 50 ± 5 m s À1 during the AM.”

Dark vortices are also dark in BL1 and MT1 maps.

“Figures 5a and 5b show that dark vortices are also dark in BL1 and MT1 maps, and are not detected at other wavelengths, consistent with low aerosol opacity (or perhaps dark coloration) at the deeper levels sensed by those filters, and no impact on the aerosol distribution or wind field at higher levels.”

The largest vortex in the study sits alone in its latitude band at 51.8°S.

“The largest vortex in our study sits alone in its latitude band at 51.8°S and drifted steadily at 50 ± 5 m s À1 during the AM.”

The AM reveals many changes in vortex drift rate and/or direction, sometimes associated with a vortex-vortex interaction or merger.

“In addition, the AM reveals many changes in drift rate and/or direction, sometimes associated with a vortex-vortex interaction or merger (see section 4.6).”

Saturn's jets, both westward and especially eastward, are sharply peaked.

“However, an important fact is that Saturn's jets, both westward and especially eastward, are sharply peaked.”

Figure 11 shows a correlation between vortex activity just south of the 41°S jet and the occurrence of convective storms.

“Figure 11 dramatically shows the correlation between vortex activity just south of the 41°S jet and the occurrence of convective storms.”

Many vortex trajectories originate at the locations where convective storms were observed.

“Many trajectories originate at the locations where convective storms were observed.”

Vortices are present near each of the locations where the barotropic stability criterion is violated.

“Vortices are present near each of these locations where the criterion is violated, but the region with the most activity (''storm alley'') violates the criterion the least.”

Both bright vortices are in a cyclonic region.

“Both of the bright vortices are in a cyclonic region, while the largest vortex we observe (at 51.8°S) is in a cyclonic region.”

Dark vortices with bright margins retain that appearance in BL1 and MT1 maps.

“Dark vortices with bright margins retain that appearance in BL1 and MT1 maps.”

Vortices in the region just south of the 41°S jet tend to drift westward with the ambient wind.

“Vortices in this region tend to drift westward with the ambient wind.”

Dark vortices are not detected at other wavelengths.

“Figures 5a and 5b show that dark vortices are also dark in BL1 and MT1 maps, and are not detected at other wavelengths, consistent with low aerosol opacity (or perhaps dark coloration) at the deeper levels sensed by those filters, and no impact on the aerosol distribution or wind field at higher levels.”

Some vortices change latitude with no apparent cause.

“Some vortices change latitude with no apparent cause.”

Nine of the mergers occurred between vortices moving toward each other in opposite directions relative to System III.

“Nine of the mergers occurred between vortices that were moving toward each other in opposite directions relative to System III.”

In some cases, the postmerger vortex had a latitude and drift rate different from those of either premerger vortex.

“In some cases, the postmerger vortex had a latitude and drift rate different from those of either premerger vortex.”

Of the 123 vortices tracked in the AMs, 91 were initially detected after the first AM.

“Of the 123 vortices tracked in the AMs, 91 were initially detected after the first AM.”

The two bright vortices are rare examples of bright features on the BL1 maps, along with the convective storm and two unclassified vortices.

“The two bright vortices are rare examples of bright features on the BL1 maps (along with the convective storm and two of our unclassified vortices), but are absent in UV3, MT2, and MT3 maps, suggesting that they are deep but contain higher cloud opacity than their surroundings at that level.”

Those bright-centered vortices closest to the pole are also bright in the BL1 maps.

“Those closest to the pole are also bright in the BL1 maps.”

Ten of the mergers were facilitated by a change in latitude in one or both vortices shortly before the merger.

“Ten of the mergers were facilitated by a change in latitude in one or both of the vortices shortly before the merger.”

The vortices that change latitude remained within a single dynamical band, i.e., one sense of latitudinal shear in the zonal wind.

“However, the vortices remained within a single dynamical band (i.e., one sense of latitudinal shear in the zonal wind).”

All but three of the mergers occurred in the band near the 41°S jet.

“All but three of the mergers occurred in the band near the 41°S jet.”

Bright-centered vortices appear progressively brighter relative to surroundings in MT1, MT2, and MT3 maps.

“Bright-centered vortices appear progressively brighter (relative to surroundings) in MT1, MT2, and MT3 maps.”

The band near the 41°S jet has nearly equal numbers of eastward and westward moving vortices.

“This band has both the largest number of vortices and nearly equal numbers of eastward and westward moving vortices.”

The longitudinally quasiperiodic, anticyclonic feature near 29.5°-33°S is relatively bright in MT2 and MT3 maps.

“The longitudinally quasiperiodic, anticyclonic feature near 29.5°-33°S is relatively bright in MT2 and MT3 maps.”

The band near the 41°S jet has the largest number of vortices.

“This band has both the largest number of vortices and nearly equal numbers of eastward and westward moving vortices.”

The two bright vortices are absent in UV3, MT2, and MT3 maps.

“The two bright vortices are rare examples of bright features on the BL1 maps (along with the convective storm and two of our unclassified vortices), but are absent in UV3, MT2, and MT3 maps, suggesting that they are deep but contain higher cloud opacity than their surroundings at that level.”

Five of the mergers were facilitated by a change in direction by one or both vortices shortly before the merger.

“Five of the mergers were facilitated by a change in direction by one or both of the vortices shortly before the merger.”

There were 24 vortex-vortex mergers in the AMs.

“There were 24 vortex-vortex mergers in the AMs.”

In the band near 41°S, vortices often circulate around one another in a counterclockwise direction.

“For example, in the band near 41°S, vortices often circulate around one another in a counterclockwise direction.”

There are two examples of vortex pairs connected by an extended filament (8000 km in one case) after passing close to one another.

“There are two examples of vortex pairs that are connected by an extended filament (8000 km in one case) after passing close to one another (Figure 7).”

Mergers reduced an initial population of 36 to 12.

“Mergers reduced an initial population of 36 to 12 (some experienced multiple mergers).”

There are 18 additional vortices with lifetimes greater than the AM sequence if those with mergers are counted.

“There are 18 additional vortices with lifetimes greater than the AM sequence if those with mergers are counted (the lifetime of the merged vortex is appended to the lifetimes of each of the premerger vortices).”

The 33 short-lived vortices were all <1100 km in diameter.

“The 33 short-lived vortices were all <1100 km in diameter.”

The region near the westward jet at ~41° latitude is the most active in both hemispheres, displaying the largest number of small vortices and bright, expanding, convective storms.

“The region near the westward jet at $41° latitude is the most active in both hemispheres, displaying the largest number of small vortices and bright, expanding, convective storms.”

The largest nonpolar vortices measured in Voyager images are larger (6000 km east-west diameter) than the largest measured in this study (4500 km).

“The largest nonpolar vortices measured in Voyager images are larger (6000 km east-west diameter) than the largest measured in our study (4500 km).”

In this study, the storm centers were located near the peak of a westward jet.

“In our study, we located the storm centers near the peak of a westward jet.”

On each planet the largest vortex sits alone within its latitude band.

“On each planet the largest vortex sits alone within its latitude band.”

The 43 vortices whose initial detection or disappearance was captured within the AMs, but not both, ranged in size up to 2300 km.

“The 43 vortices whose initial detection or disappearance was captured within the AMs, but not both, ranged in size up to 2300 km.”

The populations of long-lived vortices have a size distribution distinct from short-lived vortices.

“The populations of vortices that were long-lived (i.e., not observed to appear, merge, nor disappear within the AMs) have a size distribution that is distinct from the short-lived vortices (i.e., observed to both appear and disappear within the AMs).”

We cannot say with confidence that the magnitude of the differences in zonal velocity exceeds the error when comparing measurements from several authors, data sets, and techniques.

“However, we cannot say with confidence that their magnitude exceeds the error when comparing measurements from several authors, data sets, and techniques (not to mention that introduced by the tracers and their variation over time).”

• AssumptionRests on an assumption: Cloud features tracked in the images move with the ambient zonal wind (i.e., are passive tracers).

The combination of errors due to image navigation, feature tracking, and foreshortening at higher latitudes is estimated to be <20 pixels.

“The combination of errors due to image navigation, feature tracking, and foreshortening at higher latitudes is estimated to be <20 pixels (consistent with the low dispersion of the measurements shown below).”

• AssumptionRests on an assumption: Cloud features tracked in the images move with the ambient zonal wind (i.e., are passive tracers).

Measurements from the cylindrical and polar maps are indistinguishable where they overlap.

“Measurements from the cylindrical and polar maps are indistinguishable where they overlap.”

• AssumptionRests on an assumption: Cloud features tracked in the images move with the ambient zonal wind (i.e., are passive tracers).

Some or all of the decrease in measured equatorial wind speed may be due to the presence of tracers at higher altitudes rather than a decrease in velocity at a given level.

“Therefore some or all of the decrease in measured wind speed may be due to the presence of tracers at higher altitudes rather than a decrease in velocity at a given level.”

Several types of error are accentuated at jet peaks and high latitudes.

“Several types of error are accentuated at jet peaks and high latitudes.”

• AssumptionRests on an assumption: Cloud features tracked in the images move with the ambient zonal wind (i.e., are passive tracers).

This appearance is consistent with the presence of an upper tropospheric haze that is higher and optically thicker in the equatorial region.

“This appearance is consistent with the presence of an upper tropospheric haze that is higher and optically thicker in the equatorial region [Mun ˜oz et al., 2004;Temma et al., 2005;Pe ´rez-Hoyos et al., 2005;Karkoschka and Tomasko, 2005].”

• cites Mun ˜oz et al., 2004Not checked yet

  Not checked in the free run.

• cites Temma et al., 2005Not checked yet

  Not checked in the free run.

• cites Pe ´rez-Hoyos et al., 2005Not checked yet

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Therefore the AMs cannot reveal how the total number of vortices over all sizes varied with time.

“Therefore the AMs cannot reveal how the total number of vortices over all sizes varied with time.”

The feature in the 29.5°S-33°S region probably results from the interaction between a pair of narrow zonal jets at 31°S and 33°S.

“The feature probably results from the interaction between a pair of narrow zonal jets at 31°S and 33°S.”

There is an ambiguity in whether the very high-latitude measurements from the polar ring refer to the ambient flow or the phase speed of a wave structure.

“There is an ambiguity in whether the latter measurements refer to the ambient flow or the phase speed of a wave structure.”

• AssumptionRests on an assumption: Cloud features tracked in the images move with the ambient zonal wind (i.e., are passive tracers).

Direct measurement of the tangential velocity within vortices proved difficult.

“Direct measurement of the tangential velocity within vortices proved difficult (note the lack of azimuthal structure in Figure 7), but their sense of rotation may be inferred (though not definitively) from the shear in which they are embedded.”

The sense of rotation of vortices may be inferred, though not definitively, from the shear in which they are embedded.

“Direct measurement of the tangential velocity within vortices proved difficult (note the lack of azimuthal structure in Figure 7), but their sense of rotation may be inferred (though not definitively) from the shear in which they are embedded.”

• AssumptionThe authors state this as an assumption: The sense of rotation of vortices can be inferred from the shear in which they are embedded.

The exception bright-centered vortex at 73.5°S may be unique.

“All but one of the bright-centered vortices are in cyclonic regions, and the exception at 73.5°S does not have the same shape as the others, suggesting that it may be unique.”

The authors are not able to measure the tangential velocity of individual vortices.

“While we are not able to measure the tangential velocity of individual vortices, vortices generated in this region behave as if they are predominantly anticyclonic, based on their interactions (e.g., orbiting) and stability within a zone of anticyclonic shear in the ambient wind.”

Vortices generated in the region just south of the 41°S jet behave as if they are predominantly anticyclonic, based on their interactions and stability within a zone of anticyclonic shear.

“While we are not able to measure the tangential velocity of individual vortices, vortices generated in this region behave as if they are predominantly anticyclonic, based on their interactions (e.g., orbiting) and stability within a zone of anticyclonic shear in the ambient wind.”

Although embedded within cyclonic shear zones, the spectral pattern of bright-centered vortices is similar to that of anticyclones.

“Although they are embedded within cyclonic shear zones, this spectral pattern is similar to that of anticyclones.”

The spectral pattern of the largest vortex is consistent with its presumed cyclonic vorticity, i.e., a low-pressure center with downwelling at higher levels.

“This spectral pattern is consistent with its presumed cyclonic vorticity (i.e., that it is a low-pressure center, with downwelling at higher levels).”

• AssumptionThe authors state this as an assumption: The largest vortex at 51.8°S has cyclonic vorticity.

Some mergers are facilitated by a previous mutual interaction of vortices.

“Some mergers are facilitated by a previous mutual interaction of vortices.”

Some initial detections may not represent real vortex creation events but instead reflect the increasing ability to resolve smaller vortices as the AMs progressed.

“Some of the initial detections (of all types, but 1 and 2 in particular) may not represent real vortex creation events, but instead reflect the increasing ability to resolve smaller vortices as the AMs progressed.”

Considerations of vortex lifetimes contain ambiguity due to increasing ability to detect small vortices as the AMs progressed.

“Considerations of vortex lifetimes contain some ambiguity due to the increasing ability to detect small vortices as the AMs progressed.”

A significant difference between Jupiter and Saturn is the abundance of vortices and other dynamical features on Jupiter compared with the relatively sparse appearance of Saturn, with the caveat that features on Saturn are harder to detect.

“A significant difference is the abundance of vortices and other dynamical features on Jupiter, compared with the relatively sparse appearance of Saturn (with the caveat that features on Saturn are harder to detect).”

• AssumptionRests on an assumption: The relatively sparse appearance of Saturn compared with Jupiter is not solely due to detection difficulty.

The survey reveals striking similarities between Saturn's southern hemisphere and the northern hemisphere observed by Voyager.

“Our survey of Saturn's southern hemisphere reveals some striking similarities with the northern hemisphere observed by Voyager [Smith et al., 1981[Smith et al., , 1982;;Sromovsky et al., 1983;Ingersoll et al., 1984;Sa ´nchez-Lavega et al., 2000].”

• cites Smith et al., 1981Not checked yet

  Not checked in the free run.

• cites Sromovsky et al., 1983Not checked yet

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• cites Ingersoll et al., 1984Not checked yet

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Jupiter displays a distinct cyclone-anticyclone asymmetry, in that large cyclones exhibit less spatial coherence and become multilobed or extended conveyor belt structures.

“Jupiter displays a distinct cyclone-anticyclone asymmetry, in that large cyclones exhibit less spatial coherence and become multilobed or extended ''conveyor belt'' structures.”

These lifetimes are lower limits.

“These lifetimes are lower limits.”

Similar vortex-storm interactions have been described in each hemisphere.

“Similar vortex-storm interactions have been described in each hemisphere.”