Diurnal variation of radar reflectivity factor during intense convective clouds over Indonesia

Abstract

Intense convective clouds is represented by very high of clouds tops that produce heavy rainfall/intense convective precipitation. The vertical structure of intense convective clouds over Indonesia was investigated using radar reflectivity factor (dBZ) data from Tropical Rainfall Measuring Mission (TRMM) satellite-Precipitation Radar (PR) 2A25 product during 1998-2014. The vertical distribution of dBZ was classified into two convective cells following the classification proposed by some previous studies. The first type, Comulonimbus Tower (CbT) that contains Z threshold of 20 dBZ in 12 km altitude with at least 9 km depth and Intense Convective Clouds (ICC) that contains Z threshold of 30 and 41 dBZ at 8 and 3 km, respectively. The distribution of intense convective clouds is more frequently observed over land such as Sumatra, Kalimantan, Java and Irian Jaya than over ocean areas. To observe the pattern of vertical structure of intense convective clouds, the vertical profile of dBZ for several locations that represent land, coastal and ocean areas were analyzed. The land and coastal areas show similar vertical structure of intense convective. On seasonal basis, intense convective clouds are more frequently found during March, April and May (MAM) which coincided with the maximum of convective available potential energy (CAPE) value. Furthermore, on diurnal basis, intense convective clouds are significantly observed during 16-18 LT (local time) and 04-09 LT over mainland and ocean areas, respectively