Diurnal variation of precipitation over the Indo-China Peninsula

Two-dimensional numerical simulation

Abstract

The diurnal variation of precipitation over the Indo-China Peninsula is investigated using a two-dimensional, nonhydrostatic, and cloud-resolving numerical model. The model is initialized by the climatological monthly mean vertical profiles of zonal flow, temperature and humidity at the center of the Indo-China Peninsula in June.
The model successfully simulates the diurnal variation of precipitation. The simulated diurnal variation is as follows: convection is activated at the lee-side foot of two mountainous regions located at the west and middle of Thailand in the evening of each day; activated clouds then are organized into squall lines that travel eastward during the night at about 5-10m s^-1. These squall lines weaken around midnight.
It is concluded that the solar-synchronized life cycle of the squall lines and their eastward movement cause the nighttime maximum of the precipitation over the inland area of the Indo-China Peninsula. High resolution analysis of a convective activity index calculated from the GMS IR data over the Peninsula supports this conclusion.