A Study of Enhancing the Prediction Techniques of Lightning Over Bangladesh Based on the Lightning Potential Index and Electric Field

Abstract

The thunderstorm is a typical extreme weather event that has become one of the most alarming disasters in Bangladesh because of its more frequent occurrences and devastations in recent years. The purpose of this study is to investigate the physical and dynamical characteristics of thunderstorms using Weather Research and Forecasting (WRF) model. Three domains of 9-km, 3-km, and 1-km grid size have been used for the simulation of two events over Dhaka (25-April-2018) and Khulna (11-May-2018). The simulated results are then compared with the Bangladesh Meteorological Department (BMD) and University of Wyoming observed data. Lightning Potential Index (LPI) has been calculated by using different hydrometeors and vertical wind. For the calculation of electric field of thunder-cloud, we have considered an algorithm where ice and graupel are the main charge carriers. Convective Available Potential Energy (CAPE) and Total Total Index (TTI) are found over 1500 J/kg and 48°C respectively ten hours prior to the event. Vertical wind has been found around 4 m/s before the event. Ice and graupel mixing ratios are found at very high concentrations at cloud center. Maximum value of LPI is found 0.163 J/kg in Dhaka and 0.8 J/kg in Khulna. The electric field is found to be 70 kV/m at a vertical height of 8 km in Dhaka and -125 kV/m at a vertical height of 7 km in Khulna. All the parameters are recognized to be favorable for the occurrence of thunderstorms and lightning which indicates that the techniques used in this study may be useful to predict future thunderstorm events in Bangladesh.