Evaluation and hydrological application of TRMM and GPM precipitation products in a tropical monsoon basin of Thailand

Abstract

Watershed runoffis essential for water management. However, runoffmaterials are lacking in poorly gauged catchments and not always accessible. Microwave remote sensing offers emerging capabilities for hydrological simulation. In this study based on multi-satellite retrievals for Global Precipitation Measurement (IMERG), Tropical Rainfall Measuring Mission (TRMM) products, and World Meteorological Organization (WMO) interpolated precipitation data, we simulated runoffusing a variable infiltration capacity (VIC) model and studied the differences among the results. Then, we analyzed the impacts of the runoffon a moderate-resolution imaging spectroradiometer vegetation leaf area index (LAI) during dry seasons. The results showed that (1) IMERG V5 and TRMM products are capable of monitoring the night-day rainfall diurnal cycle and have higher correlations than the WMO daily observation interpolations. However, the WMO shows less overestimation of total precipitation than remote-sensing precipitation; (2) in the downstream, the TRMM shows better runoffsimulation accuracy in the tributaries, and the WMO shows better results in the mainstreams. Therefore, at basin outlets in mainstreams, the Nash-Sutcliffe efficiency coefficients of monthly runoffby theWMOare higher than the simulations by the TRMM; (3) for the whole basin during dry seasons, the LAI variation is correlated with the outlet runoff, which is similar to the correlation with threeto six-month accumulated precipitation. TRMM products can be used to depict both precipitation deficit and runoffdeficit, which cause vegetation variations. Our research suggests the potential of microwave precipitation products for detailed watershed runoffsimulations and water management.