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  • Hydrologic evaluation of th...
    Woods, Devon; Kirstetter, Pierre-Emmanuel; Vergara, Humberto; Duarte, Jorge A.; Basara, Jeffrey

    Journal of hydrology (Amsterdam), February 2023, 2023-02-00, Volume: 617
    Journal Article

    •A novel framework is developed for integrated hydrologic validation of satellites.•Assessment focuses on flood characteristics in favor of bulk metrics.•The effects of IMERG resolution are seen on flood peak discharge.•Basin size is also found to play a role in over or underestimation of peak discharge.•IMERG simulated floods events start earlier and end later than the MRMS benchmark. In recent years, a great amount of research has been done towards evaluating precipitation data generated by satellites, but less has focused on how these estimates and their uncertainties manifest further into the water cycle. In this study, ten years of satellite-based and ground-based radar data are used as forcings for a distributed hydrologic model across the Continental United States. They are compared using a methodology designed to assess the flood signals and characteristics generated by the model. By focusing on how well the model reproduces flood characteristics rather than fits traditional bulk statistics, this research provides robust insights into satellite precipitation deficiencies. It is found that satellite data has greater success at resolving lower magnitude flood events while tending to generate floods of longer durations. Additionally, flood managers should note that satellites tend to generate floods that characteristically both begin earlier and end later than the ground radar reference. Subsequent research is recommended into other satellite data products in order to better understand these discrepancies and mitigate or plan for them in the future. In recent years, satellites have been increasingly used to provide valuable insights on rainfall across the globe, especially in locations where radars are unable to be installed on the ground. By nature, however, the rainfall data provided by satellites has uncertainties. Large amounts of research has gone into the difference in accuracy between satellite radar and ground references, but less has focused on how these differences impact flood simulations, respectively. In this study it was found that the rainfall data from satellites tends to predict floods that are more severe (have higher magnitudes), last longer (have longer durations), and have different timings (start earlier and end later) than the reference. It is also found that satellites struggle with predictions involving extreme rainfall values. Further research is suggested to better understand these issues, as well as compare against other forms of satellite rainfall data.