Diurnal variation of summer rainfall over Taiwan and its detection using TRMM observations

A surface-based rainfall monitoring network reveals that summer rainfall ov er Taiwan exhibits a prominent diurnal variation. In this study, an attempt has been made to detect the diurnal variability of Taiwan rainfall using o bservations from the Tropical Rainfall Measuring Mission (TRMM) satellite. The results show that the diurnal patterns of Taiwan rainfall can be detect ed with TRMM Microwave Imager (TMI) observations using a satellite observat ion period of 36 or more days, and detected signals match reasonably with t hose using continuous surface observations. However, sometimes, because of the unfavorable combination of satellite sampling and the occurrence of som e transient regimes in local rainfall, there is a possibility of misinterpr eting the diurnal cycle. The TRMM precipitation radar sensor also reveals a diurnal cycle of convective and stratiform rainfall. The convective activi ty increases during the late afternoon over Taiwan, which may be the effect of convection forced by localized mass convergence caused by the sea breez e. It is of interest that TMI data indicate a significant increase of rainf all over orographic regions during the same time.