Comparing ground magnetic field perturbations from global MHD simulations with magnetometer data for the 10 January 1997 magnetic storm event

A model has been developed to calculate the perturbed magnetic field at various ground-based magnetometer sites using the output of the ionospheric currents from the Lyon-Fedder-Mobarry Global MHD code. The model uses the computed ionospheric currents and the height dependence of the electrojet current above the ground, by evaluating the penetration depth of the precipitating energetic electrons, to calculate the perturbed magnetic field on the ground using Biot-Savart's law. By applying the model to the 10 January 1997 magnetic storm event we have calculated the perturbed magnetic field for four magnetometers and compared with observations. The comparison shows reasonable agreement between observations and simulations. The model including the dependence of the current sheet height on the precipitating electron energy reduces 10% error compared to the model with fixed current sheet height. The limitations of the global MHD model in calculating perturbed ground magnetic field are also discussed.