Temporal and Spatial Evaluations of Extreme Rainfall Relationship with Daily Surface Air Temperature in Peninsular Malaysia

Extreme rainfall is expected to increase as the climate warms, with the rate of increase at 7% per degree of warming following the Clausius-Clapeyron (CC) relationship. However, studies showed that the rate of increase might not necessarily follow the relationship. This study investigates temporal and spatial variations of daily rainfall relationship with surface air temperature in Peninsular Malaysia using data from the Global Historical Climatology Network (GHCN) using a fixed temperature interval binning method and quantile regression method. Investigation reveals that a negative scaling of daily extreme rainfall was observed for all surface air temperature and percentiles investigated, in contrast with the expectations from the CC relationship. The largest seasonal variation at 99th percentile was observed in December-January (DJF), while the lowest scaling rate was in March-May (MAM). The scaling rate tends to be higher in Subang and Melaka, and lower in Bayan Lepas, Kota Bharu and Kuantan. The scaling rate also tends to be stronger at 99th percentile compared to the lower rainfall events at 95th and 75th percentile and in warmer seasons compared to colder seasons. Further, the results show that the intensity of daily extreme rainfall in Peninsular Malaysia is decreasing with increasing surface air temperature