The diurnal cycle of wind, clouds, and rain over Taiwan and the surrounding areas during the southwest monsoon rainy seasons

xii, 139 leavesHourly wind, satellite, and rain gage data to used demonstrate some differences in the diurnal cycles of wind, clouds, and rain over the island of Taiwan between the Mei-Yu (May 16 - June 15) and summer (July 16 - August 31) rainy seasons over Taiwan. The diurnal cycle of clouds over the surrounding waters is also considered. Suppression of shallow warm clouds was found southeast of Taiwan where mesolows have been frequently observed during the Mei-Yu. The suppressive effect does appear in summer as well, but is much weaker. Persistent orographic cloudiness occurs over the Central Mountain Range and is least pronounced in the late morning. In general, afternoon maxima in convective clouds and rain frequencies from the land surface heating dominate in this region. Despite generally lower cloud and rainfall frequencies during summer, the diurnal cycle is more important in summer with stronger island mean divergence and more convective instability. In the Mei-Yu, weak secondary morning maxima occur over the northern and western coastal plains and over the surrounding ocean south and west of Taiwan. Mechanisms for these differences based on the changes in the environment are discussed. Fourier analysis shows that, similar to Hawai'i, the diurnal harmonic generally explains most of the variance. The importance of the semi-diurnal harmonic varies throughout the region and is most pronounced in regions with the Mei-Yu morning maxima. Semi-diurnal tide theory does not seem to have a noticeable effect on the cloudiness and rainfall. Differences between the convective cloud and rainfall frequency patterns are also noted for application in detection of rainfall from satellite data on the island scale with complex terrain