Simulation of geomagnetic storms during the passage of magnetic clouds

The response of the Earth's magnetosphere to the passage of interplanetary magnetic clouds is simulated using a three‐dimensional magnetohydrodynamic (MHD) model. The input solar wind condition is given by the magnetic field, particle density, and plasma flow calculated from a model magnetic cloud. The cross‐polar potential (Φ p ), Joule heating and electron energy precipitation into the polar cap are calculated. Synthetic magnetic indices D st * and AE * are defined to serve as surrogates for the usual D st and AE indices, respectively. We demonstrate that Φ p ² provides a good predictor of the energy deposition into the ionosphere during storm conditions and that D st * and AE * behave qualitatively similarly to D st and AE .