Vassiliadis, D. and Weigel, R. S. and Klimas, A. J. and Kanekal, S. G. and Mewaldt, R. A. (2003) Modes of energy transfer from the solar wind to the inner magnetosphere. Physics of Plasmas, 10 (2). pp. 463-473. ISSN 1070-664X http://resolver.caltech.edu/CaltechAUTHORS:VASpop03
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Energy transport from the interplanetary plasma to Earth's inner magnetosphere occurs in a range of time scales and efficiencies. It is often hypothesized that this range is smoothly varying with radial geocentric distance, indicating the transport involves many processes, whose ranges overlap. Here we report evidence from observations, and time series analysis, and other data-based modeling which indicates that the coupling of magnetospheric relativistic electron fluxes to solar wind variables occurs in specific ranges of radial distance (L shell). These findings probably have important consequences for the understanding of physical mechanisms responsible for the acceleration in each region. We identify three distinct regions: P-0 at approximately 3<L<4 R-E, P-1 at 4<L<7 R-E, and P-2 at L>7 R-E. Each one responds to a different combination of solar wind variables, and couples to the main driver variable, the solar wind speed V-SW, in a different way. Mode P-1 is the prototypical response of the inner magnetosphere. The electron flux responds more slowly than the other two regions to V-SW (2-3 days): high-speed streams are the most geoeffective structures for that region. Mode P-0 responds significantly faster (<1 day) and seems to be more affected by the negative B-z component of the interplanetary field (probably through magnetic reconnection) and the magnitude of the field, rather than by variations in solar wind plasma variables. Region P-2 contains much lower fluxes of trapped particles than the other two, and responds rapidly (similar to1 day) to positive B-z and to lower solar wind speed. The interpretation is that these regions are representative of different modes of energy transfer from the interplanetary medium to the inner magnetosphere with implications for very different particle acceleration mechanisms.
|Additional Information:||Copyright © 2003 American Institute of Physics. Received 19 June 2002; accepted 7 November 2002. We thank D. N. Baker, M.-C. Fok, S. F. Fung, X. Li, and E. Rigler for several useful discussions. We also thank the staff of NSSDC for maintaining the OMNI database. This research was funded by NASA/LWS and NSF/SW grants.|
|Group:||Space Radiation Laboratory|
|Subject Keywords:||MAGNEOSPHERE; SOLAR WIND; GEOSYNCHRONOUS ORBIT; RADIATION BELT; RELATIVISTIC ELECTRONS; SPACE WEATHER; PREDICTION; PARTICLES; SAMPEX; STORMS; CUSP|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||03 Mar 2006|
|Last Modified:||04 Mar 2013 22:53|
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