Wavelet analysis of the magnetotail response to solar wind fluctuations during HILDCAA events

Abstract

Abstract. In this work a study of the effects of the high-intensity long-duration continuous AE activity (HILDCAAs) events in the magnetotail was conducted. The aim of this study was to search the main frequencies during HILDCAAs in the Bx component of the geomagnetic field in the magnetotail, as well as the main frequencies, at which the magnetotail responds to the solar wind during these events. In order to conduct this analysis the wavelet transform was employed during nine HILDCAA events that coincided with Cluster spacecraft mission crossing through the tail of the magnetosphere from 2003 to 2007. The most energetic periods for each event were identified. It was found that 76 % of them have periods ≤4 h. With the aim to search the periods that have the highest correlation between the IMF Bz (OMNI) component and the Cluster Bx geomagnetic field component, the cross wavelet analysis technique was also used in this study. The majority of correlation periods between the Bz (IMF) and Bx component of the geomagnetic field observed also were ≤4 h, with 62.9 % of the periods. Thus the magnetotail responds stronger to IMF fluctuations during HILDCCAS at 2–4 h scales, which are typical substorm periods. The results obtained in this work show that these scales are the ones on which the coupling of energy is stronger, as well as the modulation of the magnetotail by the solar wind during HILDCAA events.

Dynamical Complexity Transitions During High‐Intensity Long Duration Continuous Auroral Activities (HILDCAA) Events: Feature Analysis Based on Neural Network Entropy

“…Several authors have established some findings about the solar wind-magnetosphere-ionosphere coupling processes during HILDCAAs events (Chernyshov et al, 2020;Guarnieri, 2006;Hajra et al, 2013;Marques de Souza Franco et al, 2019;Obara et al, 2000;Prestes et al, 2017;Silva et al, 2017;Sobral et al, 2006;Tsurutani et al, 1990Tsurutani et al, , 2004Tsurutani et al, , 2005. The investigation carried out by Vega and Favetto (2000) reported the magnetosphere's response to perturbation by storms and Alfvén waves train.…”