Fine structure of the low-latitude mesospheric turbulence

Abstract

Rocket-borne measurements of electron density were conducted from Sriharikota (13.7°N, 80.2°E) to study the fine structure of low-latitude mesospheric neutral turbulence. Spectra of electron density fluctuations were obtained using the continuous wavelet transform (CWT), and the turbulence parameters were estimated. The present study shows that turbulence is not present continuously in the mesosphere but exists in layers of different thicknesses varying from 100 m to 3 km, interspersed by regions of stability. The most important results are the following: (1) Identification of thin layers of turbulence with 100-200 m of thickness over low latitudes. These thin layers are found to lie on the edges of the thick layers of turbulence. (2) Sharp gradients in turbulence parameters at the edge regions are detected from experimental observations for the first time. This was seen earlier in simulation studies only. (3) Satellite-observed temperatures show enhanced gravity wave activity, and it is suggested that deep convections over the continental landmass in the lower atmosphere are the major source of these gravity waves responsible for generation of turbulence. Copyright 2009 by the American Geophysical Union.