Seasonal variation of rainfall characteristics in different intensity classes over Peninsular Malaysia

Abstract

► Explored diurnal variation of rainfall over Malaysia using TRMM 3 h data. ► Studied rainfall characteristics in different intensity classes for all seasons. ► Observed diurnal variation in coastal is bimodal and unimodal in inland areas. ► Identified east coast belt as flood prone area during northeast monsoon season. ► Flash floods can occur during southwest monsoon over latitudinal belt 2–4°N. Using the rain rate from Tropical Rainfall Measuring Mission (TRMM) 3 h data, we made an attempt to explore the diurnal variation of rainfall occurrences in the spatial domain of Peninsular Malaysia. This data set is available for 10 years period from 1999 to 2008 at a high spatial resolution of 25 km latitude–longitude grid. The rainfall characteristics such as the percentage of rain occurrence and the relative contribution to the total seasonal rainfall in different intensity classes have been studied in detail for different seasons namely northeast monsoon (DJF), pre-monsoon (MAM), southwest monsoon (JJA) and early northeast monsoon (SON). We arbitrarily classified the rainfall into four different categories such as small, moderate, high and very high intensity classes. The diurnal variation of frequency of rainfall over the spatial domain of Peninsular Malaysia during different seasons is presented in detail. The diurnal variation is different in the coastal areas and the central parts of the Peninsula in all the seasons. Two peaks are noticed in the coastal areas, however, in the inland regions only a prominent single peak is observed. From the analysis of the very high intensity classes, we observed that the flash flood prone areas are east coastal belt especially the coastal belt from Kuantan to Kota Bharu during the northeast monsoon season. Isolated maxima were also observed in the western region surrounded by Klang Valley during the same season. During the southwest monsoon period, flash floods may be expected over the latitudinal belt between 2°N and 4°N. The number of occurrences of very high rainfall events and their relative contribution to the seasonal rainfall are high over the above region.