Signatures of Self-Organized Criticality in Low-Latitude Magnetosphere

HR: 18:05h
AN: NG44A-08 [Abstracts]
TI: Signatures of Self-Organized Criticality in Low-Latitude Magnetosphere
AU: WANLISS, J
EM: WANLISS@HOTMAIL.COM
AF: EMBRY-RIDDLE UNIVERSITY, 600 S. CLYDE MORRIS BLVD, LB307, DAYTONA BEACH, FL 32114, United States
AU: * URITSKY, V
EM: VURITSKY@PHAS.UCALGARY.CA
AF: UNIVERSITY OF CALGARY, DEPT OF PHYSICS AND ASTRONOMY UNIVERSITY OF CALGARY, CALGARY, AB , Canada
AB: In a series of previous publications (see e.g. Consolini, 1997; Uritsky and Pudovkin, 1998; Uritsky et al., 2002, 2006; Lui et al., 2000; Chapman and Watkins, 2001) it has been shown that spatiotemporal activity in high-latitude magnetosphere exhibits signatures of self-organized criticality (SOC) - a robust multiscale stochastic regime observed in driven nonlinear systems with many couple degrees of freedom. This regime has been identified by a set of mutually consistent scaling laws describing dynamical and statistical properties of magnetospheric substorms. Here, we report the existence of SOC in the dynamics of SYM-H index, whish is a marker of space storms and other types of low-latitude geomagnetic disturbances. The ensemble average dynamics of activity bursts in the SYM-H index are scale-free and are characterized by spreading critical scaling exponents whose values are consistent with the shape of the scaling of burst sizes versus bust lifetimes. The probability distributions for the lifetime and the size of the SYM-H bursts show robust power laws which are essentially independent of the lower activity threshold used to detect the bursts, and they extend over many orders of magnitude. The avalanche distribution exponents are also in agreement with theoretical predictions for SOC systems. All of these results, together with previous studies (Wanliss and Weygand, [2007]), begin to paint a coherent picture of critical state in the inner magnetosphere possibly associated with SOC dynamics of the ring current and other constituents of low-latitude activity.
DE: 0310 Airglow and aurora
SC: Nonlinear Geophysics [NG]
MN: 2007 Joint Assembly