Propagation of Alfvén waves in the magnetotail during substorms

Recent observations from the THEMIS mission have focused attention on the timing of events in the magnetotail during magnetospheric substorms and other periods of geomagnetic activity. Standard models of substorms have generally emphasized convective flows as the major source of energy and momentum transport; however, Alfvén wave propagation can also be an important transport mechanism. The propagation of Alfvén waves and the related field-aligned currents are studied by means of ideal MHD simulation of the tail. Perturbations of the cross-tail current can lead to the generation of such waves, and the resulting propagation both through the tail and along the plasma sheet boundary layer can lead to enhanced transport. Implications of this wave propagation on the interpretation of results from the THEMIS mission will be discussed.