Analysis of the drift of the South Atlantic Anomaly using particle monitors onboard Insight-HXMT

Abstract

Using the particle monitors aboard $Insight$-HXMT satellite, we analyzed over 6.5 years of continuous data to study the South Atlantic Anomaly (SAA) position, average count rate, and surface size, as well as its evolution from June 2017 to March 2024. We confirm the anti-correlation between the particle count rate obtained by particle monitors and the solar activity, as well as the anti-correlation between the evolution of the SAA surface size and the solar activity. Furthermore, this study confirms earlier measurements of a westward drift of the SAA with a rate of $0.343\pm {0.002}^o$/yr in longitude. However, it reveals a smaller northward drift with a rate of $0.028\pm {0.002}^o$/yr in latitude. Two irregular drifts both in longitude and latitude were observed. We suggest that the irregular drifts may be not driven by solar cycle variation of the atmosphere but may be associated with geomagnetic jerks.