[P-EM12] Coupling Processes in the Atmosphere-Ionosphere System

[PEM12-P31] Influence of the Meridional Currents of the Equatorial Electrojet on the D Magnetic Component: A Ground Magnetic Data Analysis Using Principal Component Analysis

*Xzann Garry Vincent Miranda Topacio¹、Akimasa Yoshikawa^2,3 (1.Department of Earth and Planetary Sciences, Graduate School of Sciences, Kyushu University, Fukuoka, Japan、2.Department of Earth and Planetary Sciences, Faculty of Sciences, Kyushu University, Fukuoka, Japan、3.International Research Center for Space and Planetary Environmental Science, Kyushu University, Fukuoka, Japan)

キーワード：equatorial electrojet, prinicpal component analysis, meridional currents, ground magnetic data

The equatorial electrojet (EEJ) is a prominent eastward geomagnetic current flowing at the magnetic dip equator, primarily recognized through its significant influence on the H (northward) magnetic component as observed from the ground. Besides its main eastward flow, the EEJ encompasses meridional currents flowing perpendicular to the main current, whose impact on the D (eastward) magnetic component is less understood. This study aims to elucidate the effects of the meridional currents of the EEJ on the D magnetic component by employing principal component analysis (PCA) on ground magnetic data, particularly focusing on isolating these effects from other concurrent geomagnetic influences such as the inter-hemispheric field-aligned currents (IHFACs).

Data from a ground magnetic station near the dip equator (CDO, dip. lat = 1.2) was analyzed, revealing that the first and second principal components of the D component predominantly corresponded to the IHFACs and their seasonal variations. The third principal component was preliminarily associated with the meridional currents and the intensification of the EEJ. For the H component, its first three principal components combined appeared to reflect the seasonal dynamics of the EEJ. Notably, a correlation between the second principal component of H and the third principal component of D suggests a connection with the meridional currents.

These initial findings demonstrate the potential of PCA in distinguishing EEJ-related magnetic signatures from other geomagnetic phenomena in ground-based observation data, offering insights into the three-dimensional structure of the EEJ. Future efforts will aim at validating these results through methodological refinement and comparative analyses with models, satellite data, and other resources.