Validation of Integrated MultisatellitE Retrievals for GPM (IMERG) by using gauge-based analysis products of daily precipitation over East Asia

Abstract

This paper documents the qualities of satellite-based daily precipitation products from Integrated MultisatellitE Retrievals for Global Precipitation Measurement (IMERG) over East Asia. Evaluations for a year from June 2014 to May 2015 are performed using gauge-based precipitation analysis from the Climate Prediction Center (CPC) and Global Precipitation Climatology Centre (GPCC) and other satellite-based high-resolution precipitation products, such as Tropical Rainfall Measuring Mission Multisatellite Precipitation Analysis (TMPA) and the Climate Prediction Center Morphing Method (CMORPH), are also compared. The results indicate that satellite products effectively capture seasonal variations in precipitation over East Asian land regions from spring to fall although overall underestimation with relatively low correlations is observed during winter. The verification of daily detection for various thresholds indicates that IMERG and TMPA products exhibit similarly higher correspondence to CPC while CMORPH exhibits persistent underestimation for all thresholds and especially in winter. The IMERG and TMPA products tend to underestimate with decreasing thresholds and overestimate with increasing thresholds against CPC, although this tendency is significantly reduced when validated with GPCC. Nevertheless, the overall performance of IMERG and TMPA are comparable and IMERG shows reliable performance in daily precipitation for all seasons, indicating less bias and higher skill scores against those of gauge-based precipitations. The assessment study suggests the validity of the IMERG product for daily precipitation over East Asia, and this exhibits the potential for use as reference precipitation data to validate numerical weather prediction models.