Journal cover Journal topic
Annales Geophysicae An open-access journal of the European Geosciences Union
Ann. Geophys., 27, 569-576, 2009
© Author(s) 2009. This work is distributed under
the Creative Commons Attribution 3.0 License.
05 Feb 2009
Multifractal analysis of low-latitude geomagnetic fluctuations
M. J. A. Bolzan1, R. R. Rosa2, and Y. Sahai1 1Laboratório de Física Atmosférica e Solar, Instituto de Pesquisa e Desenvolvimento, Universidade do Vale do Paraíba, UNIVAP, São José dos Campos, Brazil
2Laboratório Associado de Computação e Matemática Aplicada, Instituto Nacional de Pesquisas Espaciais, INPE, São José dos Campos, Brazil
Abstract. The technique of large deviation multifractal spectrum has shown that the high-latitude (77.5° N, 69.2° 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° S, 43.6° 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.

Citation: Bolzan, M. J. A., Rosa, R. R., and Sahai, Y.: Multifractal analysis of low-latitude geomagnetic fluctuations, Ann. Geophys., 27, 569-576,, 2009.
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