Variability of the Quasi Two-Day Wave in the Mesosphere

Abstract

The Quasi-Two-Day-Wave (QTDW) is examined through analysis of data given by the SKiYMET-radar at Dragvoll, Trondheim (63◦N,10◦E). Through spectral analysis the occurrence and generation mechanisms of the different wave modes in the QTDW is examined. In winter, the Sudden Stratospheric Warming (SSW) event disturbs the normal solstice conditions, weakening the wind and contributes to an enhancement of all wave modes in early january. The recovered, but enhanced winter conditions with strong instabilities at high altitudes amplifies the W3-mode. At summer solstice the intensification of the near-resonant W3-mode above 90km is found to be related to the dissipation of the semi-diurnal tide in that region.