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An Objective Classification of Saturn Cloud Features from Cassini ISS Images A k -means clustering algorithm is applied to Cassini Imaging Science Subsystem continuum and methane band images of Saturn's northern hemisphere to objectively classify regional albedo features and aid in their dynamical interpretation. The procedure is based on a technique applied previously to visible- infrared images of Earth. It provides a new perspective on giant planet cloud morphology and its relationship to the dynamics and a meteorological context for the analysis of other types of simultaneous Saturn observations. The method identifies 6 clusters that exhibit distinct morphology, vertical structure, and preferred latitudes of occurrence. These correspond to areas dominated by deep convective cells; low contrast areas, some including thinner and thicker clouds possibly associated with baroclinic instability; regions with possible isolated thin cirrus clouds; darker areas due to thinner low level clouds or clearer skies due to downwelling, or due to absorbing particles; and fields of relatively shallow cumulus clouds. The spatial associations among these cloud types suggest that dynamically, there are three distinct types of latitude bands on Saturn: deep convectively disturbed latitudes in cyclonic shear regions poleward of the eastward jets; convectively suppressed regions near and surrounding the westward jets; and baro-clinically unstable latitudes near eastward jet cores and in the anti-cyclonic regions equatorward of them. These are roughly analogous to some of the features of Earth's tropics, subtropics, and midlatitudes, respectively. This classification may be more useful for dynamics purposes than the traditional belt-zone partitioning. Temporal variations of feature contrast and cluster occurrence suggest that the upper tropospheric haze in the northern hemisphere may have thickened by 2014. The results suggest that routine use of clustering may be a worthwhile complement to many different types of planetary atmospheric data analysis.
Document ID
20160005811
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Del Genio, Anthony D.
(NASA Goddard Inst. for Space Studies New York, NY United States)
Barbara, John M.
(TRINNOVIM, LLC New York, NY, United States)
Date Acquired
May 4, 2016
Publication Date
February 11, 2016
Publication Information
Publication: Icarus
Publisher: Elsevier
Volume: 271
ISSN: 0019-1035
e-ISSN: 1090-2643
Subject Category
Lunar And Planetary Science And Exploration
Report/Patent Number
GSFC-E-DAA-TN30870
Funding Number(s)
CONTRACT_GRANT: NNG12HP07C
WBS: WBS 431924.04.01.01
Distribution Limits
Public
Copyright
Other
Keywords
atmosphere dynamics
morphology
image processing
Saturn
Saturn atmosphere
algorithms

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