Abstract

Doppler SODAR (Sound Detection and Ranging) is used to measure vertical velocity in order to investigate the diurnal variations in different seasons and their causative processes. Significant diurnal variations are observed in the air motion at Gadanki. This paper outlines the transitory nature of the Atmospheric Boundary Layer (ABL) a few hours before and after the time of sunset as has been studied over a tropical station, Gadanki (13.45o N, 79.18oE).With regard the afternoon transition (AT), variation is seen in temperature (T) and wind variance (s, WS), about 100 min prior to the time of the local sunset, then in the vertical temperature gradient and finally in water vapour mixing ratio. Aloft, both signal-to-noise ratio (SNR) and spectral width (s) show the AT almost at the same time. The start time of the transition shows some seasonal variation, with delayed transitions occurring mostly during the rainy and humid seasons of the northeast monsoon. Updrafts are observed in the afternoon hours in the lower ABL in all seasons whereas downdrafts are observed in the evening hours in the lower ABL during the same. The diurnal and seasonal variations of the measured convective boundary layer over this tropical station are discussed. D. Sharmila | Prof. M. P. Rao"Doppler Sodar Observations of the Diurnal Variations of the Atmospheric Boundary Layer over Gadanki, a Tropical Rural Station" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-2 | Issue-1 , December 2017, URL: http://www.ijtsrd.com/papers/ijtsrd5974.pdf http://www.ijtsrd.com/other-scientific-research-area/other/5974/doppler-sodar-observations-of-the-diurnal-variations-of-the-atmospheric-boundary-layer-over-gadanki--a-tropical-rural-station/d-sharmila

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