Properties of the solar wind parameters associated with the enhanced Russell-McPherron Effect in March 2008

Abstract

We study the properties of the solar wind parameter associated with the enhanced Russell-McPherron (R-M) effect that occurred on 8–9 March 2008. The solar wind during the period from 01:33 UT and 05:24 UT on 9 March 2008 (hereafter Period2) makes a dominant contribution to the ring current intensity of the geomagnetic storm that occurred on 8–9 March 2008. It is usually accepted that the enhanced R-M effect is due to the negative ByGSE around the spring equinox. However, we found that ByGSE are positive during most of Period2. The enhanced R-M effect described by the enhanced ring current effect estimated by the empirical formulae created by Burton et al. (1975) and by O’Brien & McPherron (2000) for the solar wind during Period2 are −33.23 nT and −26.45 nT, respectively. However, the real ring current effect caused by the solar wind during Period2 is −88.10 nT. The reason that we find is that the solar wind dynamic pressure is high during Period2. The results of this study indicate that the enhanced R-M effect described by the enhanced ring current effect not only depends BzGSM, but also depends on the solar wind dynamic pressure. The enhanced ring current effect around the spring equinox of 2008 caused by BzGSM, is amplified by the solar wind dynamic pressure by about 3 times.