Dependence of IMF By penetration into the neutral sheet on IMF Bz and geomagnetic activity

Abstract

AbstractThe penetration of interplanetary magnetic field (IMF) By into the magnetosphere plays an important role in determining magnetospheric configuration and its dynamics. In this paper, using 9 years of Cluster data at the center of neutral sheet, we statistically study the relations of the penetration of IMF By in the neutral sheet (NS) with IMF Bz and the Kp index. The correlation coefficient between NS By and IMF By is enhanced during the periods of southward IMF Bz and large Kp indexes. The penetration efficiency of IMF By, which is defined as the slope of the linear fit of the points in the By‐IMF By space, is larger during southward IMF Bz than during northward IMF Bz. The penetration efficiency of IMF By also increases with increasing Kp index. Since the Kp index can be considered as an index of magnetospheric convection, this means that the penetration of IMF By into the magnetosphere is enhanced during the periods of strong magnetospheric convection. These results indicate that the IMF Bz and magnetospheric convection can influence the neutral sheet By and even magnetotail dynamics by changing the penetration of IMF By.