Multifractal analysis of low-latitude geomagnetic fluctuations

作者：Bolzan M J A^*; Rosa R R; Sahai Y

来源：Annales Geophysicae, 2009, 27(2): 569-576.

DOI：10.5194/angeo-27-569-2009

• Magnetospheric physics
• MHD waves and instabilities
• Plasma waves and instabilities
• Space plasma physics
• Nonlinear phenomena

The technique of large deviation multifractal spectrum has shown that the high-latitude (77.5 degrees N, 69.2 degrees W) geomagnetic fluctuations can be described from direct dissipation process or loading-unloading regimes of the solar wind-magnetosphere coupling. In this paper, we analyze the H-component of low-latitude (22.4 degrees S, 43.6 degrees W) geomagnetic field variability observed during the month of July 2000 at the Geomagnetic Observatory, Vassouras, RJ, Brazil. The variability pattern during this period is a mixture of quiet and disturbed days including the Bastille Day intense geomagnetic storm on 15 July. Due to the complexity of this data, we pursue a detailed analysis of the geomagnetic fluctuations in different time scales including a multifractal approach using the singular power spectrum deviations obtained from the wavelet transform modulus maxima (WTMM). The results suggest, as observed from high-latitude data, the occurrence of low-latitude multifractal processes driving the intermittent coupling between the solar wind-magnetosphere and geomagnetic field variations. On finer scales possible physical mechanisms in the context of nonlinear magnetosphere response are discussed.

• 出版日期2009