Particle precipitation from the magnetotail and field-aligned current during substorms

Abstract

This paper is a summary of our studies on the dynamics of the magnetosphere during substorms, using particle dynamics and magnetic field and plasma data observed on the ISEE-1 and 2 satellites. Using the Tsyganenko model, we divide the magnetosphere into an adiabatic region, a non-adiabatic region near the equatorial plane, a neutral sheet adiabatic region and a precipitation region. The precipitation region links the non-adiabatic regions with the auroral oval. The motion of particles in the non-adiabatic region is stochastic and lead to a pitch angle scattering dependence on B x . We expect that this is one of the main particle precipitation sources during substorms. The variation of the mid-surface of the adiabatic region was studied by means of a displayed neutral sheet model which joints smoothly the equatorial plane. The field-aligned current in the inner magnetosphere caused by the precipitation of particle from the non-adiabatic regions is studied using the magnetometer data observed on ISEE. Using a simplified model we find an expression for Curl B. A statistical study based on magnetometer data from ISEE-1 and 2 satellites show that the spatial distribution and the variation of the region of the projections of Curl B along the magnetic field line onto the ionosphere.