Observations of reconnection of interplanetary and lobe magnetic field lines at the high-latitude magnetopause

Results are presented of ISEE 2 observations of plasma accelerations obtained at the high-latitude (lobe) magnetopause at a time when the local magnetosheath and magnetospheric magnetic fields were nearly oppositely directed and the flow speed in the magnetosheath, V(s), was nearly equal to the local Alfven speed, V(A). The observations provide direct evidence for the rereconnection of the open field lines of the tail lobes with the IMF, when the magnetic field shear is large. It is pointed out, however, that, since V(s) was almost equal to V(A), it is unlikely that the rereconnection is associated with the strong sunward convection in the polar cap.