Design and Performance Analysis of a Real-time Correction Application to the IMERG Estimated Precipitation in Ganges-Brahmaputra Basin

Ganges-Brahmaputra river basins are one of the most populous basins of the world with very less amount of in situ observations of hydrological phenomena. Hydrologists of this region are using near real-time satellite based estimations in their daily operational purposes to minimize the difficulties related to ground-based hydrological measurements. Integrated Multi-Satellite Retrievals for GPM (IMERG) estimated precipitation is becoming progressively popular among the decision makers of this region due to its derivation algorithm designed to consider all satellite microwave precipitation estimates. To improve the quality of IMERG-Early run product and filter out unrealistic predictions, we developed an automated system to apply a real-time correction on the daily basis based on the ground measured rainfall in Ganges and Brahmaputra Basin. As a part of this correction system, a web crawler is developed to crawl ground measured rainfall data over Ganges-Brahmaputra Basin from bona-fide water management agencies websites where they share precipitation of last 24 hours for a very limited period of time. Using these rainfall data, bias amount in satellite estimated precipitation is calculated and interpolated for the whole Basin. Finally, this bias amount is adjusted in the IMERG estimated precipitation to make it more realistic and accurate. In this study, we will access the relative performance of the different method of Bias interpolation which is applied to the satellite estimated precipitation. To illustrate the impacts of this correction system in streamflow estimation, a previously calibrated VIC hydrological model will be simulated and change in streamflow will also be accessed.