Comparisons of Daily Thailand Rain Gauge with GPCC and TRMM Satellite Precipitation Measurements

Daily rainfall data collected by the Thailand Meteorological Service over Thailand for the period 1993-2002 have been used to examine the characteristics of rainfall at different time and space scales. The daily gauge data consists of more than a hundred rain gauges located in five main divisions in Thailand. The gauge data are binned at 1 by 1 grids and compared with the Global Precipitation Climatology Centre (GPCC) gauge analyses and the Tropical Rainfall Measuring Mission (TRMM) and other –GPI calibration (3B42) and the TRMM merged and satellite analysis (3B43). Preliminary comparison of the gridded monthly averages shows that the gauge data are very close to the GPCC estimates, with a bias of 1.4 mm/month. The bias between 3B43 and gauge is 4.0 mm/month and between 3B42 and gauge is 27.8 mm/month, respectively. The bias and RMSD for the daily data are –0.88 and 9.71 mm/day, respectively. While the gauges tends to be lower than 3B42 overall, there are substantial regional and seasonal differences.