Including gap region field‐aligned currents and magnetospheric currents in the MHD calculation of ground‐based magnetic field perturbations

Abstract

Many high‐latitude modeling studies utilize the horizontal ionospheric Hall current in calculating ground‐based magnetic perturbations, but low‐latitude and midlatitude studies should include current systems such as the magnetospheric, field‐aligned, and Pedersen currents. Recently, by including all these current systems, a more precise ground‐based perturbation calculator has been implemented in the Space Weather Modeling Framework. Using this new method, ground‐based perturbations generated by different current systems are analyzed at low, middle, and high latitudes. As a result of the current systems, MLT‐UT maps of ground‐based perturbations are studied. Furthermore, nine storms events are simulated at more than 20 low‐latitude and midlatitude magnetometer locations and compared with observational ground‐based perturbations. These studies show that for specifying the northward component of the ground magnetic perturbations, the inclusion of magnetospheric, field‐aligned, and Pedersen current is important and improves the prediction significantly over the prediction only considering the Hall current in the calculation. The improvement is the most during the storm main phase. However, for the vertical and eastward components of the perturbations, which were typically smaller than the northward component, the inclusion of these current systems actually made the specifications worse because the ring current in the model rotates more toward the dayside than in reality.