Delineation of surface energy exchanges variations during thunderstorm and non-thunderstorm days during pre-monsoon season

Turbulent surface energy exchanges from land-air interface play an important role in generation and enhancing the convection. During pre-monsoon months (April-May) thunderstorms generate over Chota Nagpur plateau area of NE India and move over the study area Ranchi (23 degrees 25'N, 85 degrees 26'E). Even though convective conditions prevail over Ranchi during these months, thunderstorm occurs on some days only. To address this important aspect, present study focuses on understanding of surface energy budget (SEB): partitioning of net solar radiation flux (Q(N)) into sensible (Q(H)), latent heat (Q(E)) and soil heat fluxes during different epochs of thunderstorm activity over study site at Ranchi. For this purpose, micro-meteorological data sets which comprise of fast response turbulent measurements and slow response data during 2008, 2009 and 2010 over Ranchi are used. A total of 25 thunderstorm cases are selected for the present study. The study reveals that prior to the occurrence of thunderstorm the Q(H) and Q(E) fluxes reach the same order followed by soil heat flux (Q(G)). No significant variation of soil heat (Q(G)) flux is noticed between thunderstorm days and non-thunderstorm days. The variations in the partitioning of Q(N) flux into Q(H), Q(E) and Q(G) fluxes are distinguishable between the days of thunderstorm (TD) and non-thunderstorm (NTD). This variation can be used as precursor signal for the occurrence of thunderstorm activity. The results emanated from the present work are important in validating the performance of the meso-scale models in simulating these storms. (C) 2014 Elsevier Ltd. All rights reserved.