HR: 08:30h
AN: SM11B-03 INVITED    [Abstracts]
TI: Entropy conservation and entropy loss governing substorm phases and tail transport
AU: * Birn, J
EM: jbirn@lanl.gov
AF: Los Alamos National Laboratory, MS D466, PO Box 1663, Los Alamos, NM 87545, United States
AU: Hesse, M
EM: michael.hesse@nasa.gov
AF: NASA/Goddard Space Flight Center, Code 696, Greenbelt, MD 20771, United States
AU: Zaharia, S
EM: szaharia@lanl.gov
AF: Los Alamos National Laboratory, MS D466, PO Box 1663, Los Alamos, NM 87545, United States
AB: The role of entropy conservation and loss during substorm phases is discussed on the basis of MHD theory and simulations, using a comparison with PIC simulations for validation. Entropy conservation appears to be a crucial element leading to the formation of thin embedded current sheets in the late substorm growth phase and the potential loss of equilibrium. Entropy loss (in the form of plasmoids) is essential in the earthward transport of flux tubes (bubbles, bursty bulk flows), while entropy gain from general magnetic reconnection may contribute to the tailward transport of plasmoid/flux ropes (blobs). Entropy loss may also change the tail stability properties and render ballooning modes unstable and thus contribute to cross-tail variability. We illustrate these effects through results from theory and simulations. Entropy conservation also governs the accessibility of final states of evolution and the amount of energy that may be released.
DE: 2723 Magnetic reconnection (7526, 7835)
DE: 2740 Magnetospheric configuration and dynamics
DE: 2744 Magnetotail
DE: 2764 Plasma sheet
DE: 2790 Substorms
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting