MAGNETIC-FIELD AND PLASMA PROPERTIES ASSOCIATED WITH PRESSURE PULSES AND MAGNETIC RECONNECTION AT THE DAYSIDE MAGNETOPAUSE

Most of the models for the formation of magnetic flux transfer events (FTEs) at the dayside magnetopause (MP) are based on magnetic reconnection. However, it has been suggested that a wavy magnetopause motion caused by solar wind pressure variations might provide an alternative explanation. Using two-dimensional MHD simulations, we study the dynamics and the local field and plasma signatures which are caused by the interaction of enhanced pressure regions with a current layer. The results are compared with two-dimensional magnetic reconnection processes. The magnetopause motion due to the enhanced pressure agrees qualitatively with the suggested model. The earthward or sunward displacement of the magnetopause is driven by the interaction of a fast mode wave with the current sheet. However, the variation of the magnetic field component normal to the current layer BN is largely monopolar and for the considered cases typically smaller than for the reconnection cases. In addition, the magnetic field signatures depend strongly on the propagation direction of the boundary wave relative to the local magnetic field configuration. The normal magnetic field signature reverses sign across the magnetopause for large magnetic shear and propagation along the direction of antiparallel field components. In the reconnection case, the bipolar BN signature has the same polarity on both sides of the current sheet. Differences between magnetic reconnection and pressure driven boundary motions are manifold and systematic differences are summarized which can be used to test statistical ensembles of such events.