SWMF Global Magnetosphere Simulations of January 2005: Geomagnetic Indices and Cross‐Polar Cap Potential

We simulated the entire month of January 2005 using the Space Weather Modeling Framework (SWMF) with observed solar wind data as input. We conducted this simulation with and without an inner magnetosphere model and tested two different grid resolutions. We evaluated the model's accuracy in predicting K p , S Y M ‐ H , A L , and cross‐polar cap potential (CPCP). We find that the model does an excellent job of predicting the S Y M ‐ H index, with a root‐mean‐square error (RMSE) of 17–18 nT. K p is predicted well during storm time conditions but overpredicted during quiet times by a margin of 1 to 1.7 K p units. A L is predicted reasonably well on average, with an RMSE of 230–270 nT. However, the model reaches the largest negative A L values significantly less often than the observations. The model tended to overpredict CPCP, with RMSE values on the order of 46–48 kV. We found the results to be insensitive to grid resolution, with the exception of the rate of occurrence for strongly negative A L values. The use of the inner magnetosphere component, however, affected results significantly, with all quantities except CPCP improved notably when the inner magnetosphere model was on.