Improved electrodynamic modeling of an omega band and analysis of its current system

We improve a previous electrodynamic model of an omega band by applying a nonuniform spatial distribution of the Hall to Pedersen conductance ratio instead of using a constant value. The analysis of the current system due to our model reveals that after separating the background westward electrojet off, the omega band currents mainly consist of Hall currents circulating around concentrated upward field-aligned currents in the auroral tongue. However, the upward field-aligned currents exhibit a nearly circular configuration around the center of the tongue and almost vanish directly in the center. Equally strong downward field-aligned currents are missing. Additionally, at the western flank of the tongue we notice an about northwest-southeast aligned Cowling channel. Its currents are mainly responsible for the spike-like D peak in magnetograms and for the general asymmetry in D and Z longitudinal profiles on the ground. An additional enhancement of the Hall conductance in this channel further improves the agreement between calculated and measured ground magnetic disturbance profiles.