A STUDY OF THERMAL PLUMES OVER TIRUPATI USING SODAR AND MICROBAROGRAPH

An acoustic sounder, operating at a frequency of 2.2 kHz and a probing range of 1 km, has been designed and developed for the study of atmos pheric boundary layer. A detailed study of diurnal variations of heigh t, onset and dissipation timings of thermal plumes has been made and i t shows that the thermal plumes are the characteristic features of day time atmospheric conditions and do not show much seasonal variation in their occurrence. Diurnal variations of infrasonic pressure fluctuati ons have also been studied in detail using a microbarograph. Simultane ous observations made by sodar and microbarograph are able to detect t he thermal plumes in the boundary layer. In addition, sodar and microb arograph data seem to correlate well to study the thermal plume activi ty in the atmospheric boundary layer.