Authors

Z. G. Yu; V. Anh; Y. Wang; D. Mao;J. Wanliss

Comments

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Abbreviated Journal Title

J. Geophys. Res-Space Phys.

Keywords

HELIOSPHERIC MAGNETIC-FIELD; SELF-ORGANIZED CRITICALITY; NONSTATIONARY; TIME-SERIES; D-ST INDEX; MULTIFRACTAL STRUCTURE; DYNAMIC MAGNETOSPHERE; AVALANCHING SYSTEM; STORM EVENTS; LEVY NOISE; FLUCTUATIONS; Astronomy & Astrophysics

Abstract

In this paper, we investigate the characteristics and develop a stochastic model for the horizontal component B-x of the magnetic field at 22 stations of the global near-real-time magnetic observatory network INTERMAGNET. The model is in the form of a fractional stochastic differential equation. A method to estimate the parameters on the basis of observed data and to simulate the data using the model is given. The degree of fractional differentiation and the alpha-stability exponent of the process are employed to cluster the stations. The B-x time series possess pronounced local trends, which must be removed before modeling and simulation can be performed. This trend removal is carried out by an empirical mode decomposition. An outcome is an efficient method to simulate the B-x time series by empirical mode decomposition and fractional stochastic differential equation. The numerical results indicate the existence of two distinct clusters of the INTERMAGNET: one in the mid- and low latitudes consistent with the D-st index, and the other above geomagnetic latitude 60 degrees N consistent with the AE index. This clustering corresponds to the inner magnetosphere and the outer magnetosphere, respectively.

Journal Title

Journal of Geophysical Research-Space Physics

Volume

115

Publication Date

1-1-2010

Document Type

Article

Language

English

First Page

11

WOS Identifier

WOS:000285011300005

ISSN

2169-9380

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