HR: 0800h
AN: SM31A-0408    [Abstracts]
TI: The role of random fluctuations in the magnetosphere-ionosphere system: a dynamic stochastic model for AE-index variations
AU: * Pulkkinen, A
EM: antti.pulkkinen@gsfc.nasa.gov
AF: NASA Goddard Space Flight Center, Greenbelt Rd, Greenbelt, MD 20771 United States
AU: Klimas, A
EM: alex.klimas@nasa.gov
AF: NASA Goddard Space Flight Center, Greenbelt Rd, Greenbelt, MD 20771 United States
AU: Vassiliadis, D
EM: vassi@electra.gsfc.nasa.gov
AF: NASA Goddard Space Flight Center, Greenbelt Rd, Greenbelt, MD 20771 United States
AU: Uritsky, V
EM: uritsky@vu9751.spb.edu
AF: University of St. Petersburg, St. Petersburg, St. Petersburg, N/A Russian Federation
AB: Understanding the evolution of bursts of activity in the magnetosphere-ionosphere system has been one of the central challenges in space physics since, and even prior to the introduction of the term "substorm". An extensive amount of work has been put to the characterization of the average near-space plasma environment behavior during substorms and several more or less deterministic models have been introduced to explain the observations. However, although most of substorms seem to have some common characteristics (otherwise any classification would be completely meaningless), like intensification of auroral electric currents, dipolarization of the magnetotail and injections of plasma sheet charged particles, each substorm has its distinct features in terms of strong fluctuations around the average "typical" behavior. This highly complex nature of individual substorms suggests that stochastic processes may play a role, even a central one in the evolution of substorms. In this work, we develop a simple stochastic model for the AE-index variations to investigate the role of random fluctuations in the substorm phenomenon. We show that by the introduction of a stochastic component, we are able to capture some fundamental features of the AE-index variations. More specifically, complex variations associated with individual bursts are a central part of the model. It will be demonstrated that by analyzing the structure of the constructed stochastic model some presently open questions about substorm-related bursts of the AE-index can be addressed quantitatively. First and foremost, it will be shown that the stochastic fluctuations are a fundamental part of the AE-index evolution and cannot be neglected even when the average properties of the index are of interest.
DE: 2435 Ionospheric disturbances
DE: 2441 Ionospheric storms (7949)
DE: 2704 Auroral phenomena (2407)
DE: 2790 Substorms
SC: SPA-Magnetospheric Physics [SM]
MN: Fall Meeting 2005