L band wind profiler observations of convective boundary layer over Gadanki, India (13.5°N, 79.2°E)

Abstract

Results from a convection campaign, which was carried out during May–August 1999 using VHF/L band wind profiler, optical rain gauge, and radiosonde flights at National MST Radar Facility, Gadanki (13.5°N, 79.2°E), are discussed. During this period, L band wind profiler observations have been made for a total of 110 days, and radiosonde observations have been made during 19 July to 14 August 1999. L band wind profiler–derived refractive index structure constant profiles have been used to estimate the convective boundary layer (CBL) height and are compared with radiosonde observations. Comparison has shown a good agreement with a regression coefficient of 0.84 between these two independent measurements. Radiosonde observations are also used to estimate the level of free convection, which are used for studying the triggering of convection. An attempt has been made to study the evolution of the CBL in dry convection (nonprecipitating) and precipitation days. Precipitation days comprise both premonsoon and monsoon seasons. In the present study, premonsoon days are defined as the dry to wet transition period and monsoon days as the early monsoon period. The intriguing result from these studies is the distinguishable CBL evolution observed in the preconvective environments of premonsoon and monsoon periods. These observations provide evidence for the use of wind profilers to closely monitor the onset of convective instability. Furthermore, observations of the boundary layer at various geographical locations using multiplatform instruments are sought to strengthen the results depicted here. However, the results discussed here nevertheless prove the potential of the L band wind profiler as an important tool for operational meteorology and provide new insights on the usage of wind profiler observations.