Peninsular Malaysia Rainfall Phenomenon Based on Standard Precipitation Index

The purpose of this study was to identify the rainfall distribution patterns in Peninsular Malaysia using Standard Precipitation Index at different time scales which are one month, six months and twelve months. Daily rainfall data for 75 rain-gauge stations covering four zones which are Northwest, West, Southwest and East for 33 years: 1975 – 2007 were considered. The results of the analysis showed that the dispersion value for occurrence of wet/dry condition increases with higher time scale. Results on related variables which are duration, severity and inter arrival time showed that the values for maximum, average and standard deviation at all zones also increased with higher time scales. The Southwest zone was found to consistently experience longer duration of wet condition compared to dry condition, while the West zone has a relatively higher standard deviation for all variables apart from intensity.