Changes of thermospheric composition and ionospheric density caused by quasi 2-day wave dissipation

The overall thermospheric and ionospheric changes induced by the QTDW are evaluated by running the model with and without QTDW forcing imposed at the model lower boundary. The dissipation of the westward propagating QTDW in the lower thermosphere causes westward mean wind acceleration and drives a poleward meridional circulation.

The circulation induced by the QTDW, as determined by the difference between the mean wind patterns of a run with the QTDW and a base run without the QTDW, enhances the mixing of constituents in the lower thermosphere. Through molecular diffusion, the decrease of the O mixing ratio and the increase of the N₂ and O₂ mixing ratios propagate from the lower thermosphere into the upper thermosphere. As a result, the O/N₂ ratio near the ionospheric F₂ peak is reduced by about 16-20% at low and midlatitudes.