This study investigated diurnal cycles in convection and precipitation over the complex mountain-valley terrain of the southern Tibetan Plateau (TP) during the mature phase of the summer monsoon. Cloud-cover frequency (CCF) for high cloud increased after 13 LST (07 UTC) over the mountain ranges along 28.5°N and 30.2°N, reaching a maximum near 18 LST (12 UTC). Areas of high CCF subsequently moved towards the valley area along 29.3°N; relatively high CCF persisted there until early morning. Tropical Rainfall Measuring Mission (TRMM) PR data show a nearly identical variation in rainfall frequency. Formation and development of convective-type clouds and phase differences in the diurnal cycle were strongly affected by TP topography. Possible mechanisms for convective enhancement over the southern TP are also discussed.
2005 by the Meteorological Society of Japan