Influence of solar wind dynamic pressure on geomagnetic Dst index during various magnetic storms

Abstract

The Dst index, designed as a proxy of ring current intensity, is known to be also affected by other magnetospheric current systems, e.g. magnetopause current. The pressure-corrected Dst index is obtained by removing the effects of the solar wind dynamic pressure and the quiet time ring current. However, all previous studies treated the correction coefficient as an averaged parameter for storms of different intensity. In this paper, based on the Burton’s equations and employing two independent methods, we will show a positive correlation between pressure-correction coefficient b and the intensity of the storms. We divided our storm database (872 storms in total) into three categories according to the intensity of storms. In order to improve the accuracy of calculating, we also used the higher-resolution SYM-H index data instead of Dst index to compute the corrected Dst index during different storms. Furthermore, we are able to provide corrected magnetic storm index with high-time resolution (∼ 1 min).