Sherine Rachel John

TIMED/SABER observations of global gravity wave climatology and their interannual variability from stratosphere to mesosphere lower thermosphere

The present study for the first time reports the global gravity wave activity in terms of their potential energy derived from TIMED/SABER observations right from the stratosphere to the mesosphere lower thermosphere (MLT) region. The potential energy profiles obtained from SABER temperature are validated by comparing them with ground based LIDAR observations over a low latitude site, Gadanki (13.5° N, 79.2° E). The stratospheric and mesospheric global maps of gravity wave energy showed pronounced maxima over high and polar latitudes of the winter hemisphere. The interannual variability of the stratospheric gravity wave activity exhibited prominent annual oscillation over mid-latitudes. The equatorial gravity wave activity exhibited quasi-biennial oscillation in the lower stratosphere and semi-annual oscillation in the upper stratosphere. The MLT region maps revealed summer hemispheric maxima over polar latitudes and secondary maxima over the equatorial region. The results are discussed in the light of present understanding of global gravity wave observations. The significance of the present study lies in emphasizing the importance of satellite measurements in elucidating gravity waves, which is envisaged to have profound impact on parameterizing these waves.