HR: 17:20h
AN: NG44A-05    [Abstracts]
TI: Characterizing the Multiscale Phenomena of the Magnetosphere
AU: * Sharma, A
EM: ssh@astro.umd.edu
AF: University of Maryland, Department of Astronomy, College Park, MD 20742, United States
AU: Veeramani, T
EM: tmani@umd.edu
AF: University of Maryland, Department of Astronomy, College Park, MD 20742, United States
AB: The multiscale nature of the magnetospheric response to the driving by the turbulent solar wind is prototypical of open natural systems. The distribution of scales in the magnetosphere are studied using data from space- borne and ground-based measurements. The burst lifetime distribution of the AL index, which is a characteristic response of the magnetosphere, has been found to be a combination of a power law with an exponential cutoff and a log-normal function [Freeman et al., GRL, 27, 1087, 2000]. The distribution of waiting times between substorms above a certain threshold have also been shown to have a similiar behavior [Freeman et.al, Phys. Rev. E 2000]. An important feature of both these distributions is the clear deviation from the power law behavior for longer time scales. The distribution of scales in the AL index (1 min resolution) from January 1978 to June 1988 and from January 1990 to December 1995, consisting of approximately 8.6 million data points, is studied to determine the distribution of scales. There is a clear deviation of the burst duration distribution at lower thresholds from a stretched exponential and the same occurs for the waiting time distribution at higher thresholds. The stretched exponential distributions of waiting times are recognized as a universal behavior for long term correlated data, and the deviations from such a distribution in the case of the magnetosphere indicate the presence of both long and short range correlations. This implies that the magnetospheric dynamics exhibit both global and multiscale phenomena.
DE: 2784 Solar wind/magnetosphere interactions
DE: 2790 Substorms
DE: 4430 Complex systems
DE: 4468 Probability distributions, heavy and fat-tailed (3265)
DE: 4475 Scaling: spatial and temporal (1872, 3270, 4277)
SC: Nonlinear Geophysics [NG]
MN: 2007 Joint Assembly