RAINFALL CHARACTERISTICS OF TROPICAL RAIN FOREST AND TEMPERATE FOREST: COMPARISON BETWEEN BUKTT TAREK IN PENINSULAR MALAYSIA AND HITACHI OHTA IN JAPAN

Abstract

We investigated the rainfalls of both Bukit Tarek (BT; tropical rain forest) in Peninsular Malaysia and Hitachi Ohta (HO; temperate forest) in Japan from 1992 to 1994. There were no pronounced peaks in total precipitation at each time of day at HO throughout the year. However, there was a distinct diurnal cycle in precipitation at BT, where about 60 % of the rainfall occurred between 13:00 h and 19:00 h. The sine wave, which was decomposed by Fourier transform consisting of 24-h, 12-h, and 8-h cycles and applied to the observed data at. BT, was useful (r=0.97) in order tore-evaluate the diurnal cycle of precipitation. The mean amounts of rainfall in each rain event at BT and HO were almost the same (14 mm) but BT had a lower maximum value (less than 100 mm). The rainfall at BT was characterised by short duration and high intensity; about 55 % of rain events fell within 1-hour periods, testifying1 to the predominantly convectional storms. There was a high positive correlation at BT (r=0.95) between amount of rainfall in each rain event and maximum hourly rainfall intensity during rain event. Though only four rain events with more than 50 mm h"1 for 10 rnin occurred for three years at HO, such high intensity rain events occurred every month at BT. The obtained results are useful in order to analyse hydrological processes in tropical rain forest.