Impact of the interaction between the quasi-2 day wave and tides on the ionosphere and thermosphere

Abstract

The quasi-2 day wave (QTDW) can effectively interact with atmospheric tides in the mesosphere and lower thermosphere. We study the effect of this QTDW-tidal interaction on the ionosphere and thermosphere using the thermosphere-ionosphere-mesosphere electrodynamics general circulation model. This interaction reduces the amplitude of the migrating diurnal tide in the lower thermosphere by ~10 m/s in neutral winds and also generates sum and difference secondary waves in the lower thermosphere and E region ionosphere. As a result of the changed migrating diurnal tide and sum/difference secondary wave, vertical ion drift varies with local time at different longitudes by ~5 m/s. In addition, the changed migrating diurnal tide also modulates the thermospheric composition (O/N2). During a QTDW event, the ionosphere F2 region peak electron density (NmF2) is reduced due to the mixing effect of the QTDW dissipation; NmF2 also shows changes in local time variation due to the QTDW-tidal interaction. The sum and difference secondary waves can cause additional oscillations in vertical ion drift and ionospheric electron densities. The QTDW-tidal interaction is another mechanism by which the QTDW impacts the ionosphere and thermosphere, along with other mechanisms: QTDW modulation of the E region wind dynamo with a period of quasi-2 days and QTDW dissipation induced mixing in the thermosphere.