Analysis on the Global Morphology of Middle Atmospheric Gravity Waves

Abstract

AbstractUsing temperature profiles obtained by the SABER/TIMED experiment from January 2002 to December 2009, we have extracted mesoscale temperature perturbations with vertical wavelengths ranging from 2 to 10 km. Global distribution of middle atmospheric gravity wave activity is revealed by observing the temperature perturbations. Comparison shows that gravity wave fluctuations in summer and winter are stronger than those in spring and autumn, below 70 km the disturbance intensity in summer is weaker with respect to winter, and contrary above 70 km. The larger gravity waves appear in winter hemisphere and in the tropics between 25°N and 25°S. Meanwhile, the perturbation peak points in the tropics move northward with increasing altitude. Furthermore, relatively larger values of gravity wave activity are present at the edge of the Antarctic polar vortex. They also appear to vary with longitudes at equatorial latitudes, which may be resulted from wind filtering, topography, planetary wave modulations and other factors. Moreover, gravity wave disturbance intensity changes with height. It indicates a decrease at 25~30 km and an increase above 42 km. Comparing the average distribution of gravity waves of eight years at different heights, we can see that the strength of gravity waves is related to topography obviously at lower altitudes, but the relationship is not significant at higher altitudes. It indicates that the formation of gravity waves is closely correlated with topography, but in the process of propagation the distribution significantly changes with altitudes.