First VHF radar observations of tropical latitude E-region field aligned irregularities

Abstract

Indian MST radar at Gadanki (13.5°N, 79.2°E, 12.5° dip) was operated during July/August 1994, to observe the 3-m scale size field aligned irregularities associated with the lower E region. Irregularity structure was studied by using height-time variation of the echo intensity and weighted mean Doppler velocity. In this paper results of three diurnal cycles of observation are presented. Field perpendicular echoes were observed both during daytime and nighttime. A layered irregularity structure extending down to altitude below 86 Km was seen during the nighttime. The daytime structure showed a narrow echoing region with significant downward slope. Doppler velocity was in the range of 20-50 ms^-1, both during day and night and was, in general, consistent with the slope of scattering structure observed in the height-time-intensity plots.