Theoretical model of convection in the near-earth plasma sheet

Equations describing convection in the plasma sheet and auroral zone are developed. The assumptions include hot protons, cold electrons, and Birkeland currents to a uniformly conducting ionosphere. Unlike previous models, a gradient of the plasma content of flux tubes is assumed. In addition, asymmetric nightside boundary conditions are studied. The equations are simplified to the point where analytic solutions are possible. The resulting solutions show both dayside and nightside Harang discontinuities and a cross-tail component to the convection. Birkeland currents (distributed and sheet) are calculated. The best agreement to observations occurs for enhanced sunward flow on the duskside of the tail and a weak gradient of the plasma content of flux tubes along the oval. 19 references