Geophys. Res. Lett., 30(20), 2073, doi:10.1029/2003GL018302, 2003.
Diurnal variation of precipitation by moving mesoscale systems: Radar observations in northern Thailand
By K. Okumura, T. Satomura, T. Oki, and Warawut Khantiyanan
Abstract
The diurnal cycle of radar echo data observed at Om
Koi, northern Thailand, during three rainy seasons (May to
October, 1998, 1999 and 2000) are analyzed. From May to
July when southwesterly monsoons blow over the
observation area, the diurnal cycles in the leeward regions
(inland of Thailand) show a phase delay that corresponds to
the distance from the mountains. In October when the wind
direction reverses and blows from the east or northeast,
inland regions correspond to the upwind side of the
mountains and do not show clear phase shifts. The regions
near the coast of the Andaman Sea, which is the leeward in
October, show a similar phase shift of the diurnal cycle as the
inland area during May−July. The echo tracking analysis
reveals that echoes, which are triggered near the mountains
and moved to leeward regions, caused phase delays, which
depended on the lee distance.