Investigation of saturated gravity waves in the tropical lower atmosphere using radiosonde observations

Abstract

Characteristics of saturated gravity waves (GWs) in the tropical lower atmosphere, i.e., troposphere and lower stratosphere, have been investigated by utilizing ground-based radiosonde data over Gadanki (13.5°N, 79.2°E), India. The mean background structure has been examined before carrying out wave analysis, which indicates conducive conditions for ample wave activity. Derived energy components exhibit relatively higher magnitude in the lower stratosphere in comparison with the troposphere. The ratio of kinetic to potential energy shows significantly higher values in comparison with the theoretical estimates. Saturated GW spectra of the zonal wind, meridional wind, and temperature evince seasonal variability in the observed logarithmic slope, which reveals considerable variability about the modeled spectral slope. The order of the characteristic wavenumber deduced from our observations implies dominant vertical scale of the saturated GWs to be less than 3 km. Important factors responsible for variation in the globally observed saturated wavenumber spectra are discussed in the light of available literatures. Probable sources responsible for driving GWs are also mentioned. Copyright 2010 by the American Geophysical Union.