Anomalous Behavior of Vertical Wavenumber Spectra Over a Tropical Station of India

Abstract

The vertical wavenumber (VWN) spectra of height profiles of winds over a tropical station of Gadanki (13.5°N, 79.2°E; obtained using Indian Mesosphere Stratosphere Troposphere radar) show distinct nature of VWN spectra, which do not match with the so-called universal wavenumber spectra. The universal wavenumber spectra have three distinct regions: unsaturated (having log-log slope of 2), saturated (having log-log slope of −3), and turbulence region (having log-log slope of −5/3). In present work, we report the presence of positive slope at the higher end of the VWN spectra indicating the presence of unsaturated gravity waves, a kind of which is not reported so far. Many negative slopes of the order of ~−6, ~−9, and ~−12 are noticed at the end of the spectra beyond the turbulence region of the wavenumber spectra, which is also not reported in any previous studies up to now.