Azimuthally asymmetric ring current as a function of D_st and solar wind conditions

Abstract. Based on magnetic data, spatial distribution of the westward ring current flowing at |z|<3 R_E has been found under five levels of D_st, five levels of the interplanetary magnetic field (IMF) z component, and five levels of the solar wind dynamic pressure P_sw. The maximum of the current is located near midnight at distances 5 to 7 R_E. The magnitude of the nightside and dayside parts of the westward current at distances from 4 to 9 R_E can be approximated as I_night=1.75-0.041 D_st, I_noon=0.22-0.013 D_st, where the current is in MA. The relation of the nightside current to the solar wind parameters can be expressed as I_night=1.45-0.20 B_s IMF + 0.32 P_sw, where B_sIMF is the IMF southward component. The dayside ring current poorly correlates with the solar wind parameters.