Time–height variation of winds and turbulence during typical tropical pre-monsoon thunderstorm events observed from high-resolution Doppler wind lidar measurements

Abstract

High spatiotemporal resolution measurements of horizontal and vertical winds made using a Doppler wind lidar during development and mature stages of few typical tropical thunderstorm events in 2014 over a continental Indian station are used to study the dynamical changes that take place in the lower atmospheric layers close to surface. Results show significant time–height variability in horizontal wind especially 2–3 h before rainfall on ground. The recorded vertical motions on the thunderstorm days showed that during its developing stage, alternating updrafts and downdrafts are prevalent through the entire vertical column of the lower atmosphere with the magnitude of fluctuations being higher compared to those on non-thunderstorm days. Turbulence intensity is high in magnitude during the evolution of intense convection. Alternating layers of convergence and divergence with horizontally time-stratified layers of strong positive and negative wind shear are observed which seem to contribute to strengthening and vertical growth of local convection. Thus, high-resolution time–height variations in horizontal and vertical winds in the lower atmosphere during the life cycle of a tropical thunderstorm provide a better understanding of the atmospheric dynamics associated with it and short-duration heavy precipitation it produces.