Effects of ion temperature anisotropy on the interhemispheric plasma transport during plasmaspheric refilling

Effects of temperature anisotropies on the early stage refilling of the outer plasmasphere are studied by solving an appropriate set of hydrodynamic equations. The anisotropies result from the supersonic outflows from the conjugate ionospheres and from the perpendicular ion heating in the equatorial region. The equatorial ion heating affected by wave‐particle interaction is included phenomenologically. Even for the equatorial heating associated with moderate wave levels, the mirror force on the flows severely limits the interhemispheric plasma exchange. The temporal evolution of the flow developing in an empty flux tube is characterized by: (1) supersonic plasma outflows from the conjugate ionospheres, (2) reflections of the flows by the mirror force as they begin to penetrate into the opposite hemispheres, (3) formation of shocks in the reflection region and (4) propagations of the shacks to the ionospheres of the origins of the flows. In the quasi‐steady state when flow completely subsides, the density distribution in the flux tube shows distinctive large‐scale features, determined by the balance between electric, pressure and anisotropy forces. The latter force becomes significant in a broad equatorial region where Tt > > Tp and also at relatively high geomagnetic latitudes where Tt < < Tp; Tt and Tp are the perpendicular and parallel ion temperatures, respectively. The force balance at high latitudes keeps the flux tube far from completely filled with minimum density < 10−1n0, where n0 is the ionospheric density. The equatorial ion population with Tt > > Tp is found to be similar to the trapped ions observed from satellites.