A coupled solar wind-magnetosphere–ionosphere model for determining the ionospheric penetration electric field

The transpolar potential Φpc may be estimated from the solar wind as measured by the advanced composition explorer (ACE) satellite at the first Lagrangian point L1. In our model, the transpolar potential drives the region-1 (J1) currents through the ionosphere consistent with a solar-dependent ionospheric conductance. It is shown that the ionospheric potential may be derived from an equivalent Poisson equation, the solution of which gives the global distribution of the ionospheric electric field, including the penetration electric field near the equator. This eastward penetration electric field just past sunset, which is created by J1, is offset by a region-2 (J2) generated westward (shielding) electric field with an unknown rise time. We find that there is a correlation between storm-time potential enhancements and the presence of equatorial bubbles as measured on DMSP satellites. The magnetic storms of 6–7 April 2000 and 20–21 November 2003 are analyzed. In both cases, the observed presence of equatorial plasma bubbles showed better agreement with model predictions using a longer J2 rise time, consistent with Huang et al. [Huang, C.-S., Foster, J., Kelley, M.C., 2005. Long-duration penetration of the interplanetary electric field to the low-latitude ionosphere during the main phase of magnetic storms. Journal of Geophysical Research 110(A11309), doi:10.1029/2005JA011202].