TIME-DEPENDENT 3-DIMENSIONAL PETSCHEK-TYPE RECONNECTION - A CASE-STUDY FOR MAGNETOPAUSE CONDITIONS

We illustrate the implications of a generalized Petschek-type reconnec tion model for conditions prevailing at the magnetopause. Petschek's m odel is generalized through the introduction of a space-and time-varyi ng reconnection rate. Furthermore, the model can incorporate skewed ma gnetic fields with different magnitudes, a velocity shear, and differe nt densities on either side of the current sheet. Here we study a situ ation typical for. the dayside magnetopause, in which all these featur es are present. On a qualitative level, it is shown that the physical :manifestations of reconnection include phenomena which have been obse rved at the magnetopause, such as accelerated plasma flows, flux trans fer events, and surface waves. To aid a quantitative and more detailed comparison with experimental data, we present the results in a format which is similar to that used to view the plasma bulk parameters and magnetic field data obtained from spacecraft measurements. In particul ar, at several fixed positions in space we analyze the time behavior o f the magnetic field and plasma parameters resulting from a localized pulse of reconnection. This exercise reveals that although there is br oad agreement between the observations and expectations based on the m odel, several discrepancies and unexplained features still remain, suc h as the increase in the total pressure associated with some observati ons of flux transfer events. These are presumably the result of variou s simplifying assumptions made in the model. We also reach the new con clusion that application of the stress balance relation does not neces sarily guarantee the correct identification of a rotational discontinu ity traversal, and we suggest an additional identifying criterion.