Development of daily gridded rainfall dataset over the Ganga, Brahmaputra and Meghna river basins

The India Meteorological Department (IMD) gridded rainfall dataset, the 47 Bangladesh gauge rainfall observations and the Tropical Rainfall Measuring Mission (TRMM) 3B42V6 satellite data are used in the present analysis. The nearest neighbour interpolation scheme is used, wherein the interpolated values are computed from a weighted sum of observations. The Bangladesh daily gauge measured rainfall is interpolated into regular grids of 0.5 degrees x 0.5 degrees resolution every day from January 1988 to December 2007 and appended with the daily gridded dataset of the IMD over the Indian region. A similar resolution dataset of 0.5 degrees x 0.5 degrees for the TRMM-3B42V6 data from January 1998 to December 2007 is created from the original data of 0.25 degrees x 0.25 degrees resolution. To produce a merged rainfall product, all the gridded datasets are merged. The merging of datasets is done in such a way as to include the highest rainfall at each grid point from the three products. Based on the three available sets of daily observations (IMD dataset (1 degrees x 1 degrees), TRMM-3B42 (0.25 degrees x 0.25 degrees) and 46 daily station observations over Bangladesh), a dataset of 0.5 degrees x 0.5 degrees resolution on a daily scale is generated. The focus of this study is to compare the TRMM-3B42V6 rainfall data over the Ganga, Brahmaputra and Meghna (GBM) domain with observed point gauge data, and assess the possibility of using them for application in real time flood forecasting as well as to serve as a comparison tool for the baseline simulation of high resolution atmospheric models aimed at flood forecasting and climate change projections. Copyright (c) 2012 Royal Meteorological Society