Statistics on the plasma properties in the magnetosheath and the efficiency of magnetopause reconnection

Abstract:

The plasma properties in the magnetosheath, particularly the flow and magnetic flux properties, are statistically investigated by using observations from Cluster and Themis satellites. The controls of the outside conditions, such as the solar wind conditions, the interplanetary magnetic field (IMF) conditions, and the Earth's dipole tilt angles, to these properties are particularly focused in this study. In addition, the correspondence of magnetic reconnection rate on the magnetopause to the solar wind conditions are studied statistically. Magnetic reconnection rate R_MR is usually used to describe how fast magnetic reconnection proceeds or the reconnection efficiency. In the literatures, one of good agencies for reconnection rate is the plasma velocity in the reconnection inflow region V_IN, or to be more accurate, the convective electric field parallel to X line in the inflow region E=V_INB_IN. On the magnetopause of the Earth, R_MR can certainly represent the input efficiency of the IMF into the Earth's magnetosphere, if through reconnection. R_MR on the magnetopause, however, is modified by the local conditions such as the magnetic fields and plasma densities on both sides of magnetopause, and thus R_MR may vary on the magnetopause and the integral of R_MR on the whole magnetopause is required to estimate the global efficiency of the input of IMF flux into the magnetosphere. The global input efficiency of IMF flux into the magnetosphere is estimated and its responses to the solar wind and IMF conditions are also investigated in this paper.