Cloud morphology and dynamics in Saturn's northern polar region

Antuñano, Arrate; Río‐Gaztelurrutia, T. del; Sánchez‐Lavega, A.; Rodríguez‐Aseguinolaza, Javier

doi:10.1016/j.icarus.2017.07.017

Cited by 26 publications

(36 citation statements)

References 38 publications

(72 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The puffy/patchy clouds are invisible in the methane filters, so they are not part of the optically thin haze. Antunano et al () say the clouds are probably of convective origin. Consistent with the words patchy and puffy, we will call them cumulus clouds based exclusively on their morphology and the dictionary definition “a class of clouds characterized by dense individual elements in the form of puffs, mounds, or towers with tops that often resemble cauliflower.” The word cumulus is derived from the Latin word for a heap or pile, and we use it simply because it matches the clouds' appearance.…”

Section: Introductionmentioning

confidence: 99%

Saturn's Atmosphere at 1–10 Kilometer Resolution

Ingersoll

Ewald

Sayanagi

et al. 2018

Geophysical Research Letters

View full text Add to dashboard Cite

We present images of Saturn from the final phases of the Cassini mission, including images with 0.5 km per pixel resolution, as high as any Saturn images ever taken. Notable features are puffy clouds resembling terrestrial cumulus, shadows indicating cloud height, dome and bowl shaped cloud structures indicating upwelling and downwelling in anticyclones and cyclones respectively, and filaments, which are thread‐like clouds that remain coherent over distances of 20,000 km. From the coherence of the filaments, we give upper bounds on the diffusivity and kinetic energy dissipation. A radiative transfer analysis by Sanz‐Requena et al. (2018) indicates that methane‐band imagery is most useful in determining cloud and haze properties in the 60–250 mbar pressure range. Our methane‐band imagery finds haze in this pressure range covering 64°‐74°planetocentric latitude. Filaments lie within the haze, and cumulus clouds lie below it, but pressure levels are uncertain below the 250 mbar level.

show abstract

Section: Introductionmentioning

confidence: 99%

Saturn's Atmosphere at 1–10 Kilometer Resolution

Ingersoll

Ewald

Sayanagi

et al. 2018

Geophysical Research Letters

View full text Add to dashboard Cite

show abstract

“…So far, diverse numerical simulations (Morales‐Juberías et al, , ; Rostami et al, ), analytical approaches (Antuñano et al, ; Barbosa‐Aguiar et al, ; Sánchez‐Lavega et al, ), and laboratory experiments (Barbosa‐Aguiar et al, ) have been performed in order to study the nature and origin of the Hexagonal jet. However, this is still an open question.…”

Section: Discussionmentioning

confidence: 99%

“…Although some transient local cloud activity has been observed at the Hexagon jet and the north polar vortex (Antuñano et al, 2018), the zonal wind profiles of the polar regions have remained unchanged over the last 35 years, without any signs of seasonal variations (Antuñano et al, 2015;García-Melendo et al, 2011;Sánchez-Lavega et al, 2000;Sayanagi et al, 2016Sayanagi et al, , 2017. On the other hand, observations of Saturn's atmosphere in the mid and far infrared (7-1,000 μm) over the last 35 years have shown a large seasonal asymmetry in the polar temperature field between summer and winter at all altitudes above the 500-mbar pressure level (Bézard et al, 1984;Conrath & Pirraglia, 1983;Fletcher et al, 2016;Yanamandra-Fisher et al, 2001), with the presence of a warm stratospheric polar hood at the summer pole (Fletcher et al, 2007;Orton & Yanamandra-Fisher, 2005).…”

Section: Introductionmentioning

confidence: 99%

Potential Vorticity of Saturn's Polar Regions: Seasonality and Instabilities

et al. 2019

Self Cite

View full text Add to dashboard Cite

We analyze the potential vorticity of Saturn's polar regions, as it is a fundamental dynamical tracer that enables us to improve our understanding of the dynamics of these regions and their seasonal variability. In particular, we present zonally averaged quasi‐geostrophic potential vorticity maps between 68° planetographic latitude and the poles at altitudes between 500 and 1 mbar for three different epochs: (i) June 2013 (early northern summer) for the north polar region, (ii) December 2008 (late northern winter) for both polar regions, and (iii) October 2006 (southern summer) for the south, computed using temperature profiles retrieved from Cassini Composite Infrared Spectrometer data and wind profiles obtained from Cassini's Imaging Science Subsystem. The results show that quasi‐geostrophic potential vorticity maps are very similar at all the studied epochs, showing positive vorticities at the north and negative at the south, indicative of the dominance of the Coriolis parameter 2Ωsinϕ at all latitudes, except near the pole. The meridional gradients of the quasi‐geostrophic potential vorticity show that dynamical instabilities, mainly due to the barotropic term, could develop at the flanks of the Hexagon at 78°N, the jet at 73.9°S, and on the equatorward flank of both polar jets. There are no differences in potential vorticity gradients between the two hemispheres that could explain why a hexagon forms in the north and not in the south. No seasonal variability of the potential vorticity and its meridional gradient has been found, despite significant changes in the atmospheric temperatures over time.

show abstract

“…Imaging at visible and near‐infrared wavelengths by the Cassini Imaging Science Subsystem and Visible and Infrared Mapping Spectrometer shows that the polar hot spots are associated with strong cyclonic polar vortices, with peak zonal wind velocities in excess of 150 m/s near ±88.7° planetographic latitude and a local maximum in vorticity at the pole (Antuñano et al, , ; Baines et al, ; Dyudina et al, , ; Sánchez‐Lavega et al, ; Sayanagi et al, ).…”

Section: Introductionmentioning

confidence: 99%

“…The south polar vortex has two distinct eyewalls, at 89.1° S and 88.3° S, with cloud altitudes changing abruptly by 40 and 70 km, respectively (Dyudina et al, ). The north polar vortex has a more complicated, and temporally variable, cloud structure, with a relatively bright region of spiraling clouds between 89.3°N and 89.7°N surrounded by a dark ring extending to 89.1°N (Antuñano et al, ; Sanz‐Requena et al, ; Sayanagi et al, ). Images in methane band filters, which are sensitive to the amount of upper tropospheric haze, show a dark spot at both poles extending to 88.7°, indicating a hole in the tropospheric haze (Sayanagi et al, ).…”

Section: Introductionmentioning

confidence: 99%

Thermal Emission From Saturn's Polar Cyclones

Achterberg

Flasar

Bjoraker

et al. 2018

Geophysical Research Letters

View full text Add to dashboard Cite

We have used data from the Cassini Composite Infrared Spectrometer to map the temperatures in Saturn's polar cyclones at the highest spatial resolution obtained during the Cassini mission. We find temperature contrasts of 7 K in the upper troposphere within 1.4° of both poles, roughly 50 percent larger than earlier measurements at lower spatial resolution. The polar hot spots weaken with depth, disappearing near 500 mbar. In the stratosphere, the polar hot spot becomes broader, extending 4° from the poles, and weakens with altitude disappearing near 1 mbar. A thermal relaxation model shows that the tropospheric hot spot is consistent with adiabatic heating from subsidence with a vertical velocity of about −0.05 mm/s above 500 mbar. The observed temperature gradients imply that the winds in the polar cyclone decay with increasing altitude over roughly three pressure scale heights above the 200‐mbar level.

show abstract

Cloud morphology and dynamics in Saturn's northern polar region

Cited by 26 publications

References 38 publications

Saturn's Atmosphere at 1–10 Kilometer Resolution

Saturn's Atmosphere at 1–10 Kilometer Resolution

Potential Vorticity of Saturn's Polar Regions: Seasonality and Instabilities

Thermal Emission From Saturn's Polar Cyclones

Contact Info

Product

Resources

About