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

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 B yGSE 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 B zGSM , but also depends on the solar wind dynamic pressure. The enhanced ring current effect around the spring equinox of 2008 caused by B zGSM , is amplified by the solar wind dynamic pressure by about 3 times.