Magnetospheric configurations from a high-resolution data-based magnetic field model

We present first results of the magnetospheric magnetic field modeling, based on large sets of spacecraft data and a high‐resolution expansion for the field of equatorial currents. In this approach, the field is expanded into a sum of orthogonal basis functions of different scales, capable to reproduce arbitrary radial and azimuthal variations of the geomagnetic field, including its noon‐midnight and dawn‐dusk asymmetries. Combined with the existing method to model the global field of Birkeland currents, the new approach offers a natural way to consistently represent the field of both the tail and symmetrical/partial ring currents. The proposed technique is particularly effective in the modeling of the inner magnetosphere, a stumbling block for the first‐principle approaches. The new model has been fitted to various subsets of data from Geotail, Polar, Cluster, IMP‐8, and GOES‐8, GOES‐9, GOES‐10, and GOES‐12 spacecraft, corresponding to different activity levels, solar wind IMF conditions, and storm phases. The obtained maps of the magnetic field reproduce most basic features of the magnetospheric structure, their dependence on the geomagnetic activity and interplanetary conditions, as well as characteristic changes associated with the main and recovery phases of magnetic storms.