Plasma structures inside boundary layers of magnetic clouds

We analyze the plasma structures for 50 magnetic cloud boundary layers (BL_S) which were observed by the spacecraft WIND from February, 1995 to June 2003. Main discoveries are: (i) The BL is a non-pressure balanced structure, its total pressure, P_T,L, (the thermal pressure, P _th,L, plus the magnetic pressure, P_M,L) is generally less than the total pressure P_T,S and P_T,C of the front solar wind (SW) and the following magnetic clouds (MC), respectively. The rising of the P_th,L inside the BL_s is often not enough to compensate the declining of P_M,L; (U) The ratio of electron and proton temperatures, (T_e/T_p)_L, inside the BL _s is offen less than (T_e/T_p)_s and (T_e/T_p)_c in the SW and the MC, respectively, because the heating of proton is more obvious than that of electron; and (iii) The reversal jet is observed in 80% BL_s investigated, in which the reversal jets from all of three directions (± V_x, ± V_y, ± V_z), were observed in ≈25% BL_s. These basic characteristics could be associated with a possible magnetic reconnection process inside the BL_s. The results above suggest that the cloud BL owns the plasma structures different from those in the SW and MC. It is a manifestation for the existing significant dynamic interaction between the magnetic cloud and the solar wind.