Performance Evaluation of SM2RAIN-ASCAT Rainfall Product Over an Agricultural Watershed of India

Abstract

Precipitation is an essential climatic variable for any hydrological study. For hydrological studies, obtaining the observed precipitation, whether real-time or historical, has been quite challenging. In this regard, satellite-based precipitation estimates play an essential role in enhancing the present hydrologic prediction capability. They are available at a high spatiotemporal resolution with global coverage. In the present study, a satellite soil moisture (retrieved from scatterometer data)based rainfall product (SM2RAIN-ASCAT) was evaluated for its performance to the gauge-based India Meteorological Department (IMD) gridded dataset over the Betwa river basin. The evaluation of satellite-based daily rainfall was carried out based on qualitative (based on contingency table) and quantitative indicators for 2007 to 2019. In general, the SM2RAIN-ASCAT rainfall product is excellent in detecting the daily rainfall events over the Betwa basin, although some of the events are falsely detected. A fair to the good agreement has been observed between satellite rainfall against IMD rainfall product (d = 0.51 to 0.72). The mean absolute error (MAE) in satellite rainfall was found to be in the range of 2.05-3.63 mm/day. The SM2RAIN-ASCAT rainfall product is good for low rainfall events. However, high rainfall events are always underestimated. Thus, the analysis indicates that the SM2RAIN-ASCAT rainfall product can be utilized in hydrological studies of ungauged regions.