Convectively generated gravity waves observed from radiosonde data taken during MCTEX

Abstract

AbstractThe properties of gravity waves generated by deep tropical convective systems are analysed from radiosonde soundings taken during the Maritime Continent Thunderstorm Experiment, and the results compared against recent cloud‐scale numerical modelling of convectively generated waves. Fluctuations in the ascent rate of the radiosonde are used to characterize the high‐frequency waves, whereas the zonal‐wind fluctuations are used to determine the properties of the inertia–gravity waves. The density‐weighted vertical‐velocity variance shows a pronounced diurnal cycle with the largest‐amplitude gravity waves developing during the early afternoon following the development of deep convection. In contrast, the density‐weighted horizontal‐velocity variance (and, by implication, the inertia–gravity wave activity) shows no diurnal variation. Simple theoretical analysis shows that the observations on 27 November 1995 are consistent with a westward propagating gravity wave with a horizontal wavelength of 17 km and a source frequency equal to 0.007 rad s−1. These findings are consistent also with a high‐resolution numerical model simulation for the same day. Nonetheless, the character of the high‐frequency gravity waves cannot be uniquely determined from a single radiosonde sounding. Copyright © 2003 Royal Meteorological Society