(1) HyARC, Nagoya University
(2) Japan Weather Association
Diurnal variation of convection is prominent phenomenon over the Tibetan Plateau during the summer. Some previous studies have shown the relationship between convection (or precipitation) and topography over the plateau during the summer. That is, convection prevails over the mountain ranges in the afternoon, while it is enhanced over the valley in the night. This is induced by thermally-driven local circulation associated with the distribution of topography over the plateau. We focused on the time-space characteristics of diurnal cycle of convection over the mountain-valley complex terrain in the southern part of the plateau for the transition from noon to midnight. Data used in this study are GMS-IR (0.05 x 0.05 grid) and TRMM PR (0.05 x 0.05 grid) for the summer (JJAS) from 1998 to 2002. Composite diurnal cycle of convection showed that active convection area moves from the mountain ranges (along 28.5N and 30.5N) to valley area (along 29N) from 09 to 18 GMT (from 15 to 00 LST at 90E). This progress was also confirmed in precipitation fields observed by TRMM. Some case studies for July to August 1998 revealed that meso-ƒÀ scale convections over the mountain ranges in the afternoon move and expand to valley area and develop into meso-ƒ¿ scale convective cells by midnight over there. Relationship between the time-space characteristics of the diurnal cycle and synoptic circulation fields were also discussed.
Submittal Information
Name :
Date :
Hatsuki Fujinami
09-Aug-04-16:01:03
Organization :
Theme :
Core Research for Evolutional Science and Technology, Japan Science and Technology Agency. Hydrospheric Atmospheric Research Center, Nagoya University.