Magnetohydrodynamic flows and waves in the Earth's magnetotail

Several questions in the Earth's magnetotail have been raised and studied. The outline is (1) The dependence of the magnetosheath flows on the orientation of interplanetary magnetic field, (2) The surface waves at the tail magnetopause are nonsinusoidal in shape and steepened toward the Sun while moving away from the Sun. This may indicate an anomalous momentum transport process in the low-latitude boundary layer, (3) The wave power in the lobe is not large enough to supply the energy to heat the plasma sheet and to initiate a substorm as proposed by the thermal catastrophe model of Goertz and Smith (1989), and (4) Some characteristics of global MHD wave modes in the magnetotail are studied by using simultaneous measurements of waves in the solar wind, in the lobes, and on the ground.;Using multiple spacecraft observations, we show that the magnetosheath flow speed on the flanks of the magnetotail steadily exceeded the solar wind speed by 20%. We propose that the acceleration of the magnetosheath flow is achieved by magnetic tension in the draped field configuration for northward IMF. Results of a 3-D MHD simulation support the model.;We examine two intervals of multiple magnetopause crossings along the flanks of the tail on January 22 and February 15, 1978. We find that, in the presence of northward IMF, the surface waves on the magnetopause were nonsinusoidal with steepened sunward facing surfaces. We propose that the magnetic field in the magnetosheath modulates the wave form in a way that may result in an anomalous transport of momentum across the magnetopause.;We examine ULF waves (0.26 to 5 mHz) in the Earth's magnetotail lobe region. We find that the wave power in the lobe is less than 1 nT for most of the time. The power of the wave is much less than the requirement of the thermal catastrophe model of Goertz and Smith, (1989).;We examine two intervals of data containing magnetic field perturbations in the upstream solar wind, in the lobes, and on the ground to study global mode ULF waves in the magnetotail. We find that the waves in both events have a global or cavity mode characteristics. The energy of the waves with frequency of 1.3 mHz in April 10, 1978 appears to propagate antisunward with a velocity of...