On the formation of the storm-time ring current belt

It is shown that the formation of the ring current belt during geomagnetic storms is not a result of an enhanced convection which is directly driven b y the solar wind and that substorm processes are crucial in populating the ring current belt by O+ ions. In order to demonstrate our result, it is sho wn that the development of the ring current belt is closely related to the upward field-aligned currents associated with magnetospheric substorms, Thr ee: periods were chosen for this particular study, based primarily on the a vailability of the needed data: March 17-19, 1978, March 20-21, 1990, and N ovember 3-5, 1993. The correlation coefficients obtained were 0.33 between the corrected Dst and the directly driven component, indicating that the fo rmation of the ring current belt is not a result of an enhanced convection. On the other hand, the correlation coefficient between the corrected Dst a nd the unloading component is 0.81. Therefore it may be concluded that the unloading component, or, more specifically, the magnetosphere-ionosphere co upling process associated with the unloading component of substorms, plays an important role in the development of the ring current belt. Our result i s consistent with observations that O+ ions are often a dominant component in the storm-time ring current belt [Daglis, 1997].