Evidence for Gravity Waves in the Thermosphere of Saturn and Implications for Global Circulation

Zarah L. Brown; Alexander S. Medvedev; Ekaterina D. Starichenko; Tommi T. Koskinen; Ingo C.F. Müller-Wodarg

doi:10.1029/2021GL097219

Evidence for Gravity Waves in the Thermosphere of Saturn and Implications for Global Circulation

Zarah L. Brown, Alexander S. Medvedev, Ekaterina D. Starichenko, Tommi T. Koskinen, Ingo C.F. Müller-Wodarg

Research output: Contribution to journal › Article › peer-review

9 Scopus citations

Abstract

Gravity wave (GW) signatures have been derived from temperature profiles observed by Cassini/Ultraviolet Imaging Spectrograph in the Saturnian thermosphere during the Grand Finale campaign. They demonstrate upward propagation of GW packets, their saturation, and breaking. We determined wave amplitudes, potential energy, and momentum fluxes and estimated the associated wave drag imposed by dissipating harmonics on the ambient flow. The data set of 18 profiles covers the middle and high latitudes of both hemispheres, which allows for exploring the global impact of waves. The diagnostics based on the Transformed Eulerian Mean and modified geostrophy approach reveal that the GW drag induces an equatorward flow in both hemispheres, facilitating transport of heat away from the auroral zones and redistributing energy across latitudes. Like all the outer planets, Saturn's thermosphere is hundreds of degrees hotter than what follows from radiative balance and these results help to explain the observed temperatures at all latitudes.

Original language	English (US)
Article number	e2021GL097219
Journal	Geophysical Research Letters
Volume	49
Issue number	8
DOIs	https://doi.org/10.1029/2021GL097219
State	Published - Apr 28 2022

Keywords

Cassini
Saturn
dynamics
giant planet
gravity waves
thermosphere

ASJC Scopus subject areas

Geophysics
General Earth and Planetary Sciences

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10.1029/2021GL097219

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title = "Evidence for Gravity Waves in the Thermosphere of Saturn and Implications for Global Circulation",

abstract = "Gravity wave (GW) signatures have been derived from temperature profiles observed by Cassini/Ultraviolet Imaging Spectrograph in the Saturnian thermosphere during the Grand Finale campaign. They demonstrate upward propagation of GW packets, their saturation, and breaking. We determined wave amplitudes, potential energy, and momentum fluxes and estimated the associated wave drag imposed by dissipating harmonics on the ambient flow. The data set of 18 profiles covers the middle and high latitudes of both hemispheres, which allows for exploring the global impact of waves. The diagnostics based on the Transformed Eulerian Mean and modified geostrophy approach reveal that the GW drag induces an equatorward flow in both hemispheres, facilitating transport of heat away from the auroral zones and redistributing energy across latitudes. Like all the outer planets, Saturn's thermosphere is hundreds of degrees hotter than what follows from radiative balance and these results help to explain the observed temperatures at all latitudes.",

keywords = "Cassini, Saturn, dynamics, giant planet, gravity waves, thermosphere",

author = "Brown, {Zarah L.} and Medvedev, {Alexander S.} and Starichenko, {Ekaterina D.} and Koskinen, {Tommi T.} and M{\"u}ller-Wodarg, {Ingo C.F.}",

note = "Funding Information: Z. L. Brown and T. T. Koskinen acknowledge support by the NASA Cassini Data Analysis Program Grant (80NSSC19K0902). E. D. Starichenko acknowledges support by the Russian Ministry of Science and Higher Education. I. C. F. M{\"u}ller‐Wodarg acknowledges support by the UK Science and Technology Facilities Council (STFC) grant (ST/W001071/1). Publisher Copyright: {\textcopyright} 2022. American Geophysical Union. All Rights Reserved.",

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doi = "10.1029/2021GL097219",

language = "English (US)",

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AU - Brown, Zarah L.

AU - Medvedev, Alexander S.

AU - Starichenko, Ekaterina D.

AU - Koskinen, Tommi T.

AU - Müller-Wodarg, Ingo C.F.

N1 - Funding Information: Z. L. Brown and T. T. Koskinen acknowledge support by the NASA Cassini Data Analysis Program Grant (80NSSC19K0902). E. D. Starichenko acknowledges support by the Russian Ministry of Science and Higher Education. I. C. F. Müller‐Wodarg acknowledges support by the UK Science and Technology Facilities Council (STFC) grant (ST/W001071/1). Publisher Copyright: © 2022. American Geophysical Union. All Rights Reserved.

PY - 2022/4/28

Y1 - 2022/4/28

N2 - Gravity wave (GW) signatures have been derived from temperature profiles observed by Cassini/Ultraviolet Imaging Spectrograph in the Saturnian thermosphere during the Grand Finale campaign. They demonstrate upward propagation of GW packets, their saturation, and breaking. We determined wave amplitudes, potential energy, and momentum fluxes and estimated the associated wave drag imposed by dissipating harmonics on the ambient flow. The data set of 18 profiles covers the middle and high latitudes of both hemispheres, which allows for exploring the global impact of waves. The diagnostics based on the Transformed Eulerian Mean and modified geostrophy approach reveal that the GW drag induces an equatorward flow in both hemispheres, facilitating transport of heat away from the auroral zones and redistributing energy across latitudes. Like all the outer planets, Saturn's thermosphere is hundreds of degrees hotter than what follows from radiative balance and these results help to explain the observed temperatures at all latitudes.

AB - Gravity wave (GW) signatures have been derived from temperature profiles observed by Cassini/Ultraviolet Imaging Spectrograph in the Saturnian thermosphere during the Grand Finale campaign. They demonstrate upward propagation of GW packets, their saturation, and breaking. We determined wave amplitudes, potential energy, and momentum fluxes and estimated the associated wave drag imposed by dissipating harmonics on the ambient flow. The data set of 18 profiles covers the middle and high latitudes of both hemispheres, which allows for exploring the global impact of waves. The diagnostics based on the Transformed Eulerian Mean and modified geostrophy approach reveal that the GW drag induces an equatorward flow in both hemispheres, facilitating transport of heat away from the auroral zones and redistributing energy across latitudes. Like all the outer planets, Saturn's thermosphere is hundreds of degrees hotter than what follows from radiative balance and these results help to explain the observed temperatures at all latitudes.

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Evidence for Gravity Waves in the Thermosphere of Saturn and Implications for Global Circulation

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