Strong Temporal Variation Over One Saturnian Year: From Voyager to Cassini
- Creators
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Li, Liming
- Achterberg, Richard K.
- Conrath, Barney J.
- Gierasch, Peter J.
- Smith, Mark A.
- Simon-Miller, Amy A.
- Nixon, Conor A.
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Orton, Glenn S.
- Flasar, F. Michael
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Jiang, Xun
- Baines, Kevin H.
- Morales-Juberías, Raúl
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Ingersoll, Andrew P.
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Vasavada, Ashwin R.
- Del Genio, Anthony D.
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West, Robert A.
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Ewald, Shawn P.
Abstract
Here we report the combined spacecraft observations of Saturn acquired over one Saturnian year (~29.5 Earth years), from the Voyager encounters (1980–81) to the new Cassini reconnaissance (2009–10). The combined observations reveal a strong temporal increase of tropic temperature (~10 Kelvins) around the tropopause of Saturn (i.e., 50 mbar), which is stronger than the seasonal variability (~a few Kelvins). We also provide the first estimate of the zonal winds at 750 mbar, which is close to the zonal winds at 2000 mbar. The quasi-consistency of zonal winds between these two levels provides observational support to a numerical suggestion inferring that the zonal winds at pressures greater than 500 mbar do not vary significantly with depth. Furthermore, the temporal variation of zonal winds decreases its magnitude with depth, implying that the relatively deep zonal winds are stable with time.
Additional Information
© 2015 Macmillan Publishers Limited. This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported license. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0. Received: 22 April 2013; Accepted: 22 July 2013; Published online: 12 August 2013. NASA Cassini Data Analysis and Outer Planets Research Programs funded this work. We acknowledge the teams of Voyager (IRIS and ISS) and Cassini (CIRS and ISS) for providing the data sets. We also thank the anonymous reviewers for their constructive suggestions. Author contributions: L.L. measured the zonal winds from the Cassini ISS observations, computed the thermal winds, and conceived the overall research. R.K.A. retrieved the atmospheric temperature from the Cassini CIRS observations. P.J.G. and B.J.C. provided the data of atmospheric temperature retrieved from the Voyager IRIS observations. M.A.S. and X.J. took part in active discussions and provided constructive suggestions during every phase of this study. L.L., R.K.A., B.J.C., P.J.G., M.A.S., A.A.S.-M., C.A.N., G.S.O., F.M.F., X.J., K.H.B., R.M.-J., A.P.I., A.R.V., A.D.D.G., R.A.W. and S.P.E. participated in the analysis and interpretation of the results and the writing of the manuscript. The authors declare no competing financial interests.Attached Files
Published - srep02410.pdf
Supplemental Material - srep02410-s1.doc
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Additional details
- PMCID
- PMC3740281
- Eprint ID
- 63228
- Resolver ID
- CaltechAUTHORS:20151224-102602232
- NASA
- Created
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2015-12-24Created from EPrint's datestamp field
- Updated
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2021-11-10Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences (GPS)