THE CONVECTION ELECTRIC FIELD MODEL IN THE MAGNETOSPHERE

Taking the magnetic field lines as the equipotential lines, the convection field in the polar region at the ionospheric heights can be mapped into the magnetosphere where the electric field play a key role in various physical phenomena. To do this, a convection electric field in polar region and a magnetic model of magnetosphere are needed. In this paper, Volland's convection electric field model in the polar region and Tsyganenko's magnetic field model (T89) are used. It's not surprising that the electric field mapped from polar region is not a uniform dawn-dusk field. The results indicate that only in the distant magnetotail, the convection electric field can be considered as uniform dawn-dusk electric field. While, in the other region, there is not only the dawn-dusk electric field (E_y) but also the E_x and E_z. There exist three different regions in the magnetotail whose convection electric field has different characters. These characters are discussed. Generally, the dawn-dusk electric field become stronger and stronger when going from the distant magnetotail to the region near the earth. On the other hand, the electric field is stronger near the dawn and dusk magnetopause boundary than in the mid-plane.