Radar observations of daytime 150-km echoes from outside the equatorial electrojet belt over Gadanki

Abstract

We present systematic observations of daytime 150-km echoes from Gadanki (13.5°N, 79.2°E, 6.3° dip latitude). The echoing region is confined to 142-162 km altitude and show forenoon descent and afternoon ascent displaying a 'necklace shape' quite similar to that of the equatorial 150-km echoes. Signal-to-noise ratio, velocity and spectral width are as high as 13 dB above noise, -5 to 35 m s^-1 and 2 to15 m s^-1, respectively. The observed 'necklace shape' is first of its kind from Gadanki and the present observations have almost all characteristics of equatorial daytime 150-km echoes. The Gadanki radar observations hence provide first experimental evidence on the occurrence of daytime 150-km echoes outside the equatorial electrojet belt.