III. DATA PROCESSING AND RESULTS
We extract data between latitude 4°N - 22°N and longitude 95°W - 108°E which covers the Thailand region from all data sets. The rain rate at each 1x1 degree grid box is computed by weighting the gauge values at each gauge by its inverse square distance from the grid center. Monthly 3B42 are computed by averaging all daily values of the month. The statistical analyses are based on the time series of daily and monthly area averages (over 40 grid boxes). .