Magnetic reconnection: Observations on October 29, 1979, and model results

We discuss the structure of the reconnection layer as recorded by ISEE 2 during an outbound crossing of the dayside, northern magnetopause on October 29, 1979. Besides a rotational discontinuity, this crossing shows slow mode shock structure. We interpret this event theoretically in terms of magnetic field line reconnection based on a pulse-like Petschek-type model, rather than in terms of steady state reconnection on a moving magnetopause. Our model is generalized through the introduction of a space-and time-varying reconnection rate. Furthermore, the magnetic fields and velocities on either side of the magnetopause current sheet may have arbitrary strength and orientation with respect to each other; additionally, the densities on either side of the current sheet may be different in general. Using boundary/initial conditions from the spacecraft data, we calculate the temporal/spatial behavior of all reconnection-associated structures. In particular, having chosen a suitable trajectory through the magnetopause, we consider the temporal behavior of the magnetic field and plasma parameters as these reconnection-associated events pass by. The results reproduce the behavior of the data reasonably well.