Velocity of Atmospheric Gravity Waves in the F2-Region of the Ionosphere over Delhi

Abstract

Extensive measurements of the small scale fluctuations in the F2-region critical frequency made at Delhi (dip=42.4ᵒ) reveal the presence of atmospheric gravity waves. Vertical speeds of these waves have been determined from the cross, correlation of radio signals obtained from various points aligned vertically in the ionosphere. A component of the wave velocity in the magnetic meridian plane has also been obtained. These speeds lie within the permissible range of internal gravity wave speeds. Estimates of the vertical wave lengths have also been made using the observed dominant periods of these waves and the vertical speed. The observed vertical wavelengths are mostly in the range 50-500 km. These estimates provide an opportunity to evaluate the total wavelength and the trace velocity of the waves assuming the validity of the simplified theory.