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Vortices in Saturn's Northern Hemisphere (2008-2015) observed by Cassini ISS

Trammell, Harold Justin and Li, Liming and Jiang, Xun and Pan, Yefeng and Smith, Mark A. and Bering, Edgar, III and Hörst, Sarah M. and Vasavada, Ashwin R. and Ingersoll, Andrew P. and Janssen, Michael A. and West, Robert A. and Porco, Carolyn C. and Li, Cheng and Simon, Amy A. and Baines, Kevin H. (2016) Vortices in Saturn's Northern Hemisphere (2008-2015) observed by Cassini ISS. Journal of Geophysical Research. Planets, 121 (9). pp. 1814-1826. ISSN 2169-9097.

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We use observations from the Imaging Science Subsystem on Cassini to create maps of Saturn's Northern Hemisphere (NH) from 2008 to 2015, a time period including a seasonal transition (i.e., spring equinox in 2009) and the 2010 giant storm. The processed maps are used to investigate vortices in the NH during the period of 2008–2015. All recorded vortices have diameters (east‐west) smaller than 6000 km except for the largest vortex that developed from the 2010 giant storm. The largest vortex decreased its diameter from ~11,000 km in 2011 to ~5000 km in 2015, and its average diameter is ~6500 km during the period of 2011–2015. The largest vortex lasts at least 4 years, which is much longer than the lifetimes of most vortices (less than 1 year). The largest vortex drifts to north, which can be explained by the beta drift effect. The number of vortices displays varying behaviors in the meridional direction, in which the 2010 giant storm significantly affects the generation and development of vortices in the middle latitudes (25–45°N). In the higher latitudes (45–90°N), the number of vortices also displays strong temporal variations. The solar flux and the internal heat do not directly contribute to the vortex activities, leaving the temporal variations of vortices in the higher latitudes (45–90°N) unexplained.

Item Type:Article
Related URLs:
URLURL TypeDescription
Li, Liming0000-0002-5257-9849
Jiang, Xun0000-0001-8932-3807
Vasavada, Ashwin R.0000-0003-2665-286X
Ingersoll, Andrew P.0000-0002-2035-9198
Janssen, Michael A.0000-0001-5476-731X
West, Robert A.0000-0002-4320-2599
Li, Cheng0000-0002-8280-3119
Simon, Amy A.0000-0003-4641-6186
Additional Information:© 2016 American Geophysical Union. Received 28 JUN 2016; Accepted 2 SEP 2016; Accepted article online 8 SEP 2016; Published online 30 SEP 2016. We gratefully acknowledge the Cassini ISS team for recording the raw data sets. We also acknowledge the support from the NASA ROSES Cassini Data Analysis and Participating Scientists program and Planetary Data Archiving, Restoration, and Tools program. Finally, we thank the two anonymous reviewers for providing their constructive suggestions to significantly improve the manuscript. We used the new Cassini data in 2015, which are not archived in the public Planetary Data System (PDS) ( yet. The 2015 Cassini ISS raw data will be released by the Cassini ISS team and archived in the PDS in late 2016. We cannot archive the processed 2015 data before the release of the ISS raw data, so we plan to archive the data of the processed NH maps in the atmospheres node of PDS ( in the beginning of 2017 or so.
Funding AgencyGrant Number
Subject Keywords:Saturn; atmosphere; Cassini/ISS; vortex; temporal variation
Issue or Number:9
Record Number:CaltechAUTHORS:20180416-075622098
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Official Citation:Trammell, H. J., et al. (2016), Vortices in Saturn's Northern Hemisphere (2008–2015) observed by Cassini ISS, J. Geophys. Res. Planets, 121, 1814–1826, doi:10.1002/2016JE005122
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:85867
Deposited By: Tony Diaz
Deposited On:16 Apr 2018 21:16
Last Modified:09 Mar 2020 13:19

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