Keywords:global MHD simulation, surface charging
Surface charging of artificial satellite is one of risks caused by dynamical variations of space environment. It occurs when a satellite exposes high energy electrons around 10 keV created by plasma injection accompanied with substorm. Therefore we want to predict timing and electron energy of plasma injection using magnetosphere-ionosphere coupling global MHD simulation. Now we are developing a real-time numerical simulator for space weather forecast using magnetosphere-ionosphere coupling global MHD simulation called REPPU (REProduce Plasma Universe) code. The feature of the simulation code is highly robust to extreme solar wind parameters because the unstructured grid system has no singular point and is able to calculate in the uniform accuracy over the whole region. We use the real-time solar wind data formatted in the GSM coordinate system observed by DSCOVR spacecraft. Magnetic-dipole axis is fixed to z-direction in our simulation. Therefore daily variation of magnetic-dipole axis is not reproduced. Instead, we convert the input direction of the solar wind velocity and magnetic field into that which tilts including daily variation of magnetic dipole axis in x-z plane. In the method the solar wind structure is not exact. However we can relatively reproduce the magnetosphere response including daily variation of the magnetic-dipole axis against solar wind. The resolution is 7682 grids in the horizontal direction and 240 grids in the radial direction.
In this presentation, we compare the simulation results with the CPCP, AE index, and plasma variations observed by geostationary orbit satellites. Density and temperature of plasma injection derived from MHD simulation tends to estimate larger and smaller values than observation respectively because the MHD simulation does not include kinetic heating effects. We have to interpret MHD simulation results for prediction of electron density and temperature. We will discuss how to interpret electron density and temperature between observation and MHD simulation.