A global morphology of gravity wave activity in the stratosphere revealed by the GPS occultation data (GPS/MET)

For each occultation event, we can evaluate a potential energy Ep which is assumed to be caused by atmospheric gravity waves. The monthly mean values of Ep at 15 - 20 km around Japan showed an annual variation with an enhancement in winter, which is consistent with the climatological behavior of the kinetic energy of gravity waves observed with the MU (middle and upper atmosphere) radar (34.9°N, 136.0°E) from 1985 to 1989.

We have then derived the global distribution of Ep at 20 - 30 km during Northern Hemisphere winter (from November to February). Our analysis shows that the largest Ep values are generally centered around the equator between 25°N and 25°S with considerable longitude variations. Longitudinal variations of Ep at 20 - 30 km in a latitude range of 30° - 60°N are also analyzed, resulting in larger Ep values over the continents than over the Pacific Ocean.