Generation of electric field in the Earth magnetosphere, caused by processes in the bow shock

Abstract Plasma of solar wind (SW) crosses the front of bow shock (BS) together with SW magnetic field trapped in it. Therefore, in the coordinate system connected with the BS front, there appears electric field proportional to the tangential component of magnetic field and to the normal (to front) component of plasma velocity. These both values vary along the front, and the electric potential varies with them. Behind the BS front there is a flow of the modified solar wind plasma: transition layer (magnetosheath), which also carries the modified magnetic field of solar wind. Velocity and density of plasma, as well as parameters of magnetic field of this current, can be estimated if the form of BS front and of magnetopause are considered known. In this paper we assumed them to be paraboloids of rotation. As Heikkila [1997. Interpretation of recent AMPTE data at the magnetopause. Journal of Geophysical Research, 102(A2), 2115–2124] has shown, the condition of energy penetration into the magnetosphere is magnetopause non-equipotentiality. In this paper we have determined potential distribution along magnetopause from the balance condition of substance coming into transition layer from SW on one side and leaving through the gap between magnetosphere and the BS front and through magnetopause on the other. To first approximation, this distribution differs from potential distribution at the BS front only in a constant multiplier. We used the established potential distribution as a boundary condition while solving the problem on potential distribution in the magnetosphere. The first solution harmonic turned out to coincide in the form with the boundary condition on magnetopause. Therefore, we have constructed the full solution for electric field in the magnetosphere having limited ourselves to the first harmonic and corotation field. The solution obtained has completely coincided with the simple empirical model [Lyons and Willer, 1987. Magnetospheric Physics. Mir, Moscow, Russia (in Russian)] suggested on the basis of the observation data synthesis. It should be noted that our model was obtained directly from the first principles.