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Saturn's Auroral Response to the Solar Wind: Centrifugal Instability ModelWe describe a model initially presented by Sittler et al. [2006] which attempts to explain the global response of Saturn's magnetosphere and its corresponding auroral behavior to variations in the solar wind. The model was derived from published simultaneous Hubble Space Telescope (HST) auroral images and Cassini upstream measurements taken during the month of January 2004. These observations show a direct correlation between solar wind dynamic pressure and (1) auroral brightening toward dawn local time, (2) an increase of rotational movement of auroral features to as much as 75% of the corotation speed, (3) the movement of the auroral oval to higher latitudes and (4) an increase in the intensity of Saturn Kilometric Radiation (SKR). This model is an alternative to the reconnection model of Cowley et al. [2004a,b; 2005] which is more Earth-like while ours stresses rotation. If angular momentum is conserved in a global sense, then when compressed the magnetosphere will tend to spin up and when it expands will tend to spin down. With the plasma sheet outer boundary at L approximates 15 we argue this region to be the dominant source region for the precipitating particles. If radial transport is dominated by centrifugal driven flux tube interchange motions, then when the magnetosphere spins up, outward transport will increase, the precipitating particles will move radially outward and cause the auroral oval to move to higher latitudes as observed. The Kelvin-Helmholtz instability may contribute to the enhanced emission along the dawn meridian as observed by HST. We present this model in the context of presently published observations by Cassini.
Document ID
20080037609
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Sittler, Edward C.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Blanc, Michel F.
(Centre d'Etude Spatiale des Rayonnements Toulouse, France)
Richardson, J. D.
(Massachusetts Inst. of Tech. Cambridge, MA, United States)
Date Acquired
August 24, 2013
Publication Date
May 26, 2008
Subject Category
Lunar And Planetary Science And Exploration
Meeting Information
Meeting: Joint meeting of the American Astronautical Society/Science Programs Division, American Geophysical Union
Location: Fort Lauderdale, FL
Country: United States
Start Date: May 26, 2008
End Date: May 30, 2008
Distribution Limits
Public
Copyright
Other

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