During rainy season, Tropical Cyclones (TCs) regularly provide heavy rain over Indochina. In addition, the monsoon trough also produces rainfall to support agricultural activities across the area. However, the extreme rainfall events usually occur during the seasonal monsoon march. Understanding the precipitating cloud characteristics produced by the extreme rainfall events could alleviate the destruction of natural resources over Indochina. The variation in precipitating clouds can be analyzed using fine spatio-temporal resolution data, such as ground-based radar data from multiple radar stations. Since the Chao Phraya river basin is the most important basin in Thailand, this study is based on radar images collected from the five installed radar stations of the Thai Meteorological Department over this basin. The analysis of the extreme rain events during rainy season in 2018 was carried out using the developed mosaic method. Python and Open Source Computer Vision Library (OpenCV) were used in the development of mosaic products to focus on characteristics of precipitating clouds. Beam-blockage fraction was analyzed for each radar station and surrounding terrain using an open source library for processing weather radar data (wradlib) (Heistermann et al., 2013) with our developed beam-blockage analysis program. The severity of blocked beam is found over the northern mountain region of study area. The precipitating clouds were detected and their parameters extracted using the ellipse fitting technique. The analysis of these clouds revealed that, among other cases, Sontihn TC was a severely destructive event based on the storm parameters of both stratiform and convective clouds. The number and length of the convective storms during Sontihn TC was the most severe when compared to other events. It has been found that the diurnal cycle of the convective cloud shows their patterns by following solar heating surface over the study area for all of the selected events.
Author Biography
Mahavik N.
Department of Natural Resources and Environment, Faculty of Agriculture Natural Resources and Environment, Naresuan University, Phitsanulok, 65000, Thailand
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