Evidence of changes in the low-latitude plasma drift under IMF $B_z$ coupling: a TIEGCM simulation approach

TL;DR

This study uses TIEGCM simulations to analyze how the north-south component of IMF $B_z$ influences low-latitude plasma drifts during a major geomagnetic storm, revealing significant shifts and increases in westward plasma motion.

Contribution

It demonstrates the impact of actual IMF $B_z$ values on low-latitude plasma drifts during a geomagnetic storm using TIEGCM simulations, an initial step in understanding space weather effects.

Findings

Significant westward shift in plasma drift with actual IMF $B_z$ data

Increase in peak westward drift after pre-reversal enhancement

Initial insights into plasma motion variations during geomagnetic storms

Abstract

Study of the dynamic nature of low-latitude ionosphere during geomagnetically disturbed conditions, especially in the EIA and the magnetic equatorial regions are vital for understanding the underlying physics as well as for mitigating space weather hazards on the sophisticated technological systems essential for human civilization. An important aspect of the space weather studies is the thorough understanding of coupling between the solar wind and the terrestrial magnetosphere-ionosphere system and subsequent influence on the low-latitude ionosphere. This paper presents an effort to understand the influence of actual values of the north-south component of Interplanetary Magnetic Field (IMF, $B_z$) on the vertical plasma drifts at a location near the EIA and the geomagnetic equator. The strong storm event of October 13, 2016, falling in the descending phase of solar cycle 24, has been taken up as a case study. Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM) simulation runs have been performed under two scenarios: first when no coupling is present (IMF $B_z$ = 0 nT) and second when actual observations of the values of IMF $B_z$ is given as inputs to the model. Observations show when actual data is fed to the model, there is significant shift of the vertical drift towards westward, while there is an increase in the peak value of the westward drift after the pre-reversal enhancement. This study is an initial effort to understand the variations in low-latitude plasma motions during the main phase of strong geomagnetic storms. This initial work will be followed up with understanding the global plasma drift variations under the influence of other components of the IMF near the EIA and the dip equatorial regions.