How do IMERG and GSMaP precipitation estimates perform in hydrological modeling: A global perspective

Built on the success of the Tropical Rainfall Measuring Mission (TRMM), the NASA/JAXA Global Precipitation Measurement (GPM) mission comprises new precipitation measurement instruments and a constellation of international satellites to provide the next-generation global observations of precipitation. The improved measurements and spatial-temporal resolution of GPM IMERG and GSMaP precipitation estimates have expanded the availability for various research and applications. However, few studies have explored their potentials in advancing global hydrological modeling.

Therefore, this study is proposed to present a broader view of IMERG and GSMaP improvements against TMPA and other commonly used products to better understand their advantages and limitations. Both near- and post-real-time products of IMERG and GSMaP will be comprehensively evaluated and compared, aiming to provide guidance and implications for users to accommodate their research and operational applications. The analysis and comparison will be conducted using in-situ rainfall and streamflow observations as well as multiple precipitation products (e.g., TMPA, CMOPRH, GPCP, CPC Unified, ERA-5, MSWEP). The results show that the hydrological performance of IMERG and GSMaP tends to be consistent in most of the globe while the difference varies across regions. For example, the simulations driven by near-real-time product of IMERG tend to overestimate discharge in the central U.S. plains, while GSMaP tends to show underestimation in the tropics.