Impact of the solar wind dynamic pressure on the Region 2 field-aligned currents

Abstract

The relationship between the Region 2 field-aligned currents and the solar wind dynamic pressure is investigated using magnetic field data from Defense Meteorological Satellite Program-F13 (DMSP-F13). The generation of the Region 2 currents is associated with the direction of the magnetic pressure gradient in the magnetosphere, in relation to that of the thermal pressure gradient. Past spacecraft observations have suggested that the spatial distribution of the magnetic pressure in the magnetosphere varies with the solar wind dynamic pressure. Therefore, we can expect that the Region 2 currents would depend on the solar wind dynamic pressure. We compared the Region 2 field-aligned current intensity at the altitude of the ionosphere, as derived using magnetic field data from DMSP-F13, with the solar wind dynamic pressure derived from 0MNI2 hourly data. It was confirmed that the Region 2 current intensity depends on the solar wind dynamic pressure during magnetic storms. During nonstorm times, however, the correlation between the Region 2 currents and the solar wind dynamic pressure is weak. The weak correlation during nonstorm times suggests that the plasma pressure in the ring current region is also essential for the effect of the solar wind dynamic pressure on the Region 2 currents. © 2009.