Temporal Variations of Strength and Location of the South Atlantic Anomaly as Measured by RXTE

TL;DR

This study analyzes the evolution of the South Atlantic Anomaly's size, strength, and location over a decade using RXTE data, revealing correlations with solar activity and geomagnetic jerks.

Contribution

It provides new insights into the temporal variations and irregularities of the SAA, linking them to solar activity and geomagnetic field changes.

Findings

SAA size and strength are anti-correlated with solar radio flux.

The SAA drifts westwards at about 0.3 deg/yr.

Irregular eastward movements of the SAA are linked to geomagnetic jerks.

Abstract

The evolution of the particle background at an altitude of ~540 km during the time interval between 1996 and 2007 is studied using the particle monitor of the High Energy X-ray Timing Experiment on board NASA's Rossi X-ray Timing Explorer. A special emphasis of this study is the location and strength of the South Atlantic Anomaly (SAA). The size and strength of the SAA are anti-correlated with the the 10.7 cm radio flux of the Sun, which leads the SAA strength by ~1 year reflecting variations in solar heating of the upper atmosphere. The location of the SAA is also found to drift westwards with an average drift rate of about 0.3 deg/yr following the drift of the geomagnetic field configuration. Superimposed to this drift rate are irregularities, where the SAA suddenly moves eastwards and where furthermore the speed of the drift changes. The most prominent of these irregularities is found in the second quarter of 2003 and another event took place in 1999. We suggest that these events are previously unrecognized manifestations of the geomagnetic jerks of the Earth's magnetic field.