Semi diurnal lunar tides in the MLT at mid and high northern and southern latitudes during major sudden stratospheric warming events

Abstract:

From recent ground- and satellite-based observations as well as from model results, it is well known that lunar tide signatures are amplified significantly during northern hemisphere sudden stratospheric warming events (SSWs). Such signatures have been observed in the equatorial and low latitude ionosphere and mesosphere, and at the mesosphere and lower thermosphere (MLT) at the northern mid and high latitude mesosphere. More recently, ionospheric signatures at mid-latitudes have been also observed in satellite instruments and such observations are corroborated with model results when the lunar tides are included. From these results (N. Pedatella, personal communication), there is a strong hemispheric asymmetry, where ionospheric perturbations occur primarily in the southern hemisphere. Motivated by these results, in this work we compare the tidal signatures in the MLT region at mid and high latitudes in both hemispheres. We make use of MLT winds obtained with specular meteor radars (SMR) at Juliusruh (54^oN), Andøya (69^oN), Rio Grande (54^oS), and Davis (69^oS) around the 2009 and 2013 major SSWs. In addition we complement our studies, with model results from the Whole Atmosphere Community Climate Model Extended version (WACCM-X) combined with the thermosphere-ionosphere-mesosphere electrodynamics general circulation model (TIME-GCM) and the inclusions of lunar tides. Besides these results, we present a brief description and preliminary results of our new approach to derive wind fields in the MLT region using multi-static, multi-frequency specular meteor radars, called MMARIA.