Initial Results in Global Flood Monitoring Using GPM Data
Abstract:The Global Flood Monitoring System (GFMS) (http://flood.umd.edu) has been developed and used to provide real-time flood detection and streamflow estimates over the last few years with significant success shown by validation against global flood event data sets and observed streamflow variations. It has become a tool for various national and international organizations to appraise flood conditions in various areas, including where rainfall and hydrology information is limited. The GFMS has been using the TRMM Multi-satellite Precipitation Analysis (TMPA) as its main rainfall input. Now, with the advent of NASA’s Global Precipitation Measurement (GPM) mission there is an opportunity to significantly improve global flood monitoring and forecasting.
GPM’s Integrated Multi-satellitE Retrievals for GPM (IMERG) multi-satellite product is designed to take advantage of various technical advances in the field and combine that with an efficient processing system producing “early” (6 hrs) and “late” (16 hrs) products for operational use. The products are also more uniform in results than TMPA among the various satellites going into the analysis and available at finer time and space resolutions.
On the road to replacing TMPA with the IMERG in the operational version of the GFMS parallel systems were run for periods to understand the impact of the new type of data on the streamflow and flood estimates. Results of this comparison are the basis for this presentation. It is expected that an improvement will be noted both in the accuracy of the precipitation estimates and a smoother transition in and out of heavy rain events, helping to reduce “shock” in the hydrology model. The finer spatial resolution should also help in this regard. The GFMS will be initially run at its primary resolution of 1/8th degree latitude/longitude with both data sets to isolate the impact of the rain information change. Other aspects will also be examined, including higher latitude events, where GPM precipitation algorithms should also provide improvements. This initial work will help focus full implementation of the IMERG into GFMS and the retrospective calculations to be done for the full TRMM/GPM era.