Global asymmetry in $\Delta$X variations during the 06 April 2000 geomagnetic storm: Relative roles of IMF Bz and By

TL;DR

This study investigates how the interplay between IMF Bz and By components causes asymmetries in ionospheric variations during a major geomagnetic storm, highlighting the role of global convection patterns and DP2 currents.

Contribution

It reveals the relative influence of IMF Bz and By on ionospheric asymmetries during a geomagnetic storm using SuperDARN and SuperMAG data, emphasizing the importance of IMF By/Bz ratio.

Findings

Asymmetry in $ abla$X variations linked to IMF By magnitude.

Global DP2 convection patterns influence ionospheric asymmetries.

IMF By/Bz ratio significantly affects ionospheric responses.

Abstract

This investigation is directed to understand the asymmetry in $\Delta$X variations caused due to the relative roles played by IMF Bz and IMF By in a particular interval (22:22 - 22:55 UT), during the main phase of a strong geomagnetic storm event of April 06, 2000 (Ap = 236). Two pairs of antipodal stations, being part of the SuperMAG network, are considered here. Ionospheric convection maps from SuperDARN network are used to understand spatio-temporal evolution of the DP2 ionospheric convection patterns over high-latitudes. The two-dimensional maps of equivalent currents are used to show signatures of global DP2 currents associated with the interplay effect between the two IMF components. Observations show increases in the difference in $\Delta$X variations between nearly antipodal stations from the Japanese-European/African sector with respect to the same between the nearly antipodal stations from the Pacific/American-Indian sector. This asymmetry is observed during the period when the absolute magnitude of IMF By is larger than that of IMF Bz resulting in a significant and conspicuous enhancement in IMF |By/Bz|. It is suggested that the distortions in DP2 cells and associated rotation of electrodynamic day-night divider, bring one pair of stations under the same DP2 cell and one station of the other pair under a different DP2 cell and throat flow region leading to the asymmetry in $\Delta$X variations between the antipodal stations. Therefore, the work highlights the importance of the interplay between IMF Bz and IMF By in determining the ionospheric impact over low latitudes during strong geomagnetic conditions.