The Winter Diurnal Circulation and Its Influence on Precipitation over the Coastal Area of Northern Taiwan

Abstract

Wind and rainfall data for December, January and February, 1976?80, over the northern coastal area of Taiwan were analyzed to examine the diurnal patterns of these parameters. Results show that the diurnal variation of rainfall was strongly modulated by the diurnal cycle of local circulation. Local circulations exhibit maximum onshore flow and divergence at 1400 LST and maximum offshore flow and convergence in 0200?0500 UT. Convective heavy rainfall appears to be triggered by the diurnal divergence pattern. Finally, the diurnal rainfall was primarily controlled by the dynamical processes within the planetary boundary layer and the thermodynamic process only plays a minor role in modifying the temporal rainfall pattern.