Morphology of large-scale traveling atmospheric disturbances in the polar thermosphere

Using a fully coupled thermosphere-ionosphere-plasmasphere model, we investigate the morphology of modelled Large-Scale Traveling Atmospheric Disturbances (LS-TADs, hereinafter TADs) propagating both poleward and equatorward from auroral sources. We confirm observational evidence of daytime ion-drag, reducing equatorward far-field TAD activity. We further suggest an additional source-dependent mechanism that associates TADs propagating preferentially poleward with an auroral electric field burst that contains an eastward rather than a westward component. These poleward TADs are superimposed on the high-speed neutral air winds in the polar cap (originating from the day-night plasma convection) and exhibit speed and spatial resonance effects with the neutral wind. The direction of propagation is affected by Coriolis forcing due to the Earth's rotation.

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