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The atmosphere of Jupiter has east–west zonal jets that alternate as a function of latitude as tracked by cloud motions at tropospheric levels. Above and below the cold tropopause at ~100 mbar, the equatorial atmosphere is covered by hazes at levels where thermal infrared observations used to characterize the dynamics of the stratosphere lose part of their sensitivity. James Webb Space Telescope observations of Jupiter in July 2022 show these hazes in higher detail than ever before and reveal the presence of an intense (140 m s−1) equatorial jet at 100–200 mbar (70 m s−1 faster than the zonal winds at the cloud level) that is confined to ±3° of the equator and is located below stratospheric thermal oscillations that extend at least from 0.1 to 40 mbar and repeat in multiyear cycles. This suggests that the new jet is a deep part of Jupiter’s Equatorial Stratospheric Oscillation and may therefore vary in strength over time.

On May 31, 2020 a short-lived convective storm appeared in one of the small cyclones of Jupiter's South Temperate Belt (STB) at planetographic latitude 30.8S. The outbreak was captured by amateur astronomer Clyde Foster in methane-band images, became widely known as Clyde's Spot, and was imaged at very high resolution by the Junocam instrument on board the Juno mission 2.5 days later. Junocam images showed a white two-lobed cyclonic system with high clouds observed in the methane-band at 890 nm. The storm evolved over a few days to become a dark feature that showed turbulence for months, presented oscillations in its drift rate, and slowly expanded, first into a Folded Filamentary Region (FFR), and later into a turbulent segment of the STB over a timescale of one year. On August 7, 2021, a new storm strikingly similar to Clyde's Spot erupted in a cyclone of the STB. The new storm exhibited first a similar transformation into a turbulent dark feature, and later transformed into a dark cyclone fully formed by January 2022. We compare the evolution into a FFR of Clyde's Spot with the formation of a FFR observed by Voyager 2 in 1979 in the South South Temperate Belt (SSTB) after a convective outburst in a cyclone that also developed a two-lobed shape. We also discuss the contemporaneous evolution of an additional cyclone of the STB, which was similar to the one were Clyde's Spot developed. This cyclone did not exhibit visible internal convective activity, and transformed from pale white in 2019, with low contrast with the environment, to dark red in 2020, and thus, was very similar to the outcome of the second storm. This cyclone became bright again in 2021 after interacting with Oval BA. We present observations of these phenomena obtained by amateur astronomers, ground-based telescopes, Hubble Space Telescope and Junocam. This study reveals that short-lived small storms that are active for only a few days can produce complex longterm changes that extend over much large

A fin de estudiar la naturaleza de las estructuras de vientos en Saturno, se presenta un análisis de la turbulencia del hemisferio sur del planeta a través del cálculo de la potencia espectral de los trazadores pasivos de su atmósfera. Se analiza el comportamiento espectral de cortes fotométricos cubriendo el paralelo completo, en latitudes comprendidas entre los 15 º y los 45 ºS. Además, se mide el perfil de vientos, tanto zonales como meridionales, mediante el uso del correlador PICV3 y el método manual de cloud tracking, abarcando las latitudes entre los 0 º y los 70 ºS. Para ambos trabajos se emplean imágenes en el filtro CB2 obtenidas en febrero de 2005 por la misión Cassini., Saturnoko haize-egituren izaera aztertzeko helburuarekin, planetaren hego hemisferioaren turbulentziaren analisia aurkezten da bere atmosferako trazatzaile pasiboen potentzia espektralaren kalkuluaren bidez. Paralelo osoa barne hartzen duten ebaki fotometrikoen jokaera espektrala aztertzen da, 15 º eta 45 ºS arteko latitudeetan. Gainera, zonaldeko zein hegoaldeko haizearen profila kalkulatzen da PICV3 korreladorearekin eta cloud tracking eskuzko metodoa erabiliz, 0 º eta 70 ºS arteko latitudeak barne hartzen. Bi lanetarako Cassini misioak 2005eko otsailean CB2 iragazkiarekin lortutako irudiak erabiltzen dira., In order to study the nature of Saturn’s wind structures, an analysis of the planet’s southern hemisphere turbulence is made by calculating the power spectra of the passive tracers of its atmosphere. Spectral behavior of photometric cuts across all of the planet’s longitudes are analysed, between latitudes of 15 º and 45 ºS. Furthermore, a profile of zonal and meridional winds is measured by the PICV3 correlator and through the cloud tracking method between latitudes of 0 º and 70 ºS. For both analyses, images with the CB2 filter from the Cassini mission, February 2005, were used.

132 p., En esta tesis, estudiamos la dinámica de las regiones polares de Saturno a nivel de las nubes de amoniaco desde 60º a 90º latitud mediante el análisis de imágenes multiespectrales de muy alta resolución capturadas por las cámaras del instrumento Imaging Science System (ISS) de la nave Cassini entre Octubre 2006 y Septiembre 2014 en longitudes de onda del visible entre el ultravioleta (~ 400 nm) y el infrarrojo cercano (~ 1000 nm) y nos centramos en la comparación de la dinámica entre ambas regiones polares. Con el fin de estudiar la dinámica de estas regiones, medimos el movimiento horizontal de las nubes y construimos mapas de viento zonal y meridional, junto con perfiles de viento zonal medio, desde 60º hasta el polo. Por otro lado, construimos mapas de vorticidad relativa y mapas bisimensionales de vorticidad potencial tanto de Ertel como quasi-geostrófica. Además, con el propósito de entender la naturaleza de la dinámica observada en ambas regiones polares, caracterizamos la morfología nubosa de la región polar norte de Saturno a diferentes longitudes de onda y analizamos su variación temporal. Finalmente, estudiamos varias posibles interpretaciones de la naturaleza del Hexágono, utilizando los vientos obtenidos al inicio de la tesis. Los resultados de este estudio nos muestran que la dinámica en ambas regiones polares es muy similar, alcanzando valores tanto de velocidades zonales como de vorticidades muy similares en ambos casos. Por otro lado vemos que, a pesar de observar variaciones en la apariencia del vórtice polar norte y actividad de tipo convectiva en el Hexágono, ninguna de estas estructuras muestra cambios estacionales en su dinámica.

The zonal wind profile of Saturn has a unique structure at 60°N with a double-peaked jet that reaches maximum zonal velocities close to 100 ms−1. In this region, a singular group of vortices consisting of a cyclone surrounded by two anticyclones was active since 2012 until the time of this report. Our observation demonstrates that vortices in Saturn can be long-lived. The three-vortex system drifts at u = 69.0 ± 1.6 ms−1, similar to the speed of the local wind. Local motions reveal that the relative vorticity of the vortices comprising the system is ∼2–3 times the ambient zonal vorticity. In May 2015, a disturbance developed at the location of the triple vortex system, and expanded eastwards covering in two months a third of the latitudinal circle, but leaving the vortices essentially unchanged. At the time of the onset of the disturbance, a fourth vortex was present at 55°N, south of the three vortices and the evolution of the disturbance proved to be linked to the motion of this vortex. Measurements of local motions of the disturbed region show that cloud features moved essentially at the local wind speeds, suggesting that the disturbance consisted of passively advecting clouds generated by the interaction of the triple vortex system with the fourth vortex to the south. Nonlinear simulations are able to reproduce the stability and longevity of the triple vortex system under low vertical wind shear and high static stability in the upper troposphere of Saturn.

We present a study of the cloud morphology and motions in the north polar region of Saturn, from latitude ∼ 70°N to the pole based on Cassini ISS images obtained between January 2009 and November 2014. This region shows a variety of dynamical structures: the permanent hexagon wave and its intense eastward jet, a large field of permanent “puffy” clouds with scales from 10 – 500 km, probably of convective origin, local cyclone and anticyclones vortices with sizes of ∼1,000 km embedded in this field, and finally the intense cyclonic polar vortex. We report changes in the albedo of the clouds that delineate rings of circulation around the polar vortex and the presence of “plume-like” activity in the hexagon jet, in both cases not accompanied with significant variations in the corresponding jets. No meridional migration is observed in the clouds forming and merging in the field of puffy clouds, suggesting that their mergers do not contribute to the maintenance of the polar vortex. Finally, we analyze the dominant growing modes for barotropic and baroclinic instabilities in the hexagon jet, showing that a mode 6 barotropic instability is dominant at the latitude of the hexagon.

Saturn has an intense and broad eastward equatorial jet with a complex three-dimensional structure mixed with time variability. The equatorial region experiences strong seasonal insolation variations enhanced by ring shadowing, and three of the six known giant planetary-scale storms have developed in it. These factors make Saturn's equator a natural laboratory to test models of jets in giant planets. Here we report on a bright equatorial atmospheric feature imaged in 2015 that moved steadily at a high speed of 450 ms(-1) not measured since 1980-1981 with other equatorial clouds moving within an ample range of velocities. Radiative transfer models show that these motions occur at three altitude levels within the upper haze and clouds. We find that the peak of the jet ( latitudes 10 degrees N to 10 degrees S) suffers intense vertical shears reaching + 2.5 ms(-1) km(1), two orders of magnitude higher than meridional shears, and temporal variability above 1 bar altitude level. Palabras clave