Model of semidiurnal pseudo-tide in the high-latitude upper mesosphere

We present numerical results for the m=1 meridional winds of semidiurnal oscillations in the high-latitude upper mesosphere, which are generated in the Numerical Spectral Model (NSM) without solar excitations of the tides. Identified with heuristic computer runs, the pseudo-tides attain amplitudes that are, at times, as large as the non-migrating tides produced with standard solar forcing. Under the influence of parameterized gravity waves, the nonlinear NSM generates internal oscillations like the quasi-biennial oscillation, which are produced with periods favored by the dynamical properties of the system. The Coriolis force would favor at polar latitudes the excitation of 12 h periodicity. This oscillation may help explain the large non-migrating semidiurnal tides that are observed in the region with ground-based and satellite measurements.

► Pseudo tides generated in a nonlinear model without solar excitation. ► Pseudo tides at times larger than those produced with solar forcing. ► This helps explain large non-migrating semidiurnal tides observed in the region.