Assessment of high-resolution satellite rainfall products over a gradually elevating mountainous terrain based on a high-density rain gauge network

Abstract

ABSTRACT High-resolution satellite rainfall products (SRPs) provide forcing inputs for hydrologic applications. Complex mountainous terrains have a significant effect on the occurrence and intensity of rainfall. This study focuses on the assessment of errors and rainfall detection capability of SRPs over a complex terrain with an elevation ranging from −95 to 3091 m based on a high-density rain gauge network over the Taihang Mountains of North China. The performance of four high-resolution SRPs (rain gauge bias-corrected Climate Prediction Center morphing technique (CMORPH CRT), Integrated Multi-satellite Retrievals for Global Precipitation Measurement (IMERG), Tropical Rainfall Measuring Mission (TRMM) 3B42V7; and Precipitation Estimation from Remotely Sensed Information using Artificial Neural Network-Cloud Classification System (PERSIANN-CCS)) was validated using 104 rain gauge stations from 1 January 2016 to 31 December 2017, and the results show that the annual rainfall varied from 375 mm to 1400 mm on average in 2016 and 2017. At the monthly scale, all SRPs except PERSIANN-CCS performed well. The spatial pattern of the annual rainfall variation, which was highest in the southeast and lowest in the northwest, was adequately captured by IMERG and 3B42 but not CMORPH CRT and PERSIANN-CCS. As indicated by the statistical metrics, all SRPs except PERSIANN-CCS exhibited better performance in the regions in the downward direction of the East-Asian Monsoon. In terms of rainfall detection, all SRPs exhibited moderate rainfall detection capability while IMERG exhibited the lowest false alarm ratio (FAR) equal to 0.41. Compared with 3B42, a significant improvement was found in IMERG, which presented increased correlation coefficient (r) and decreased FAR values over the study areas, and the improvement rate was 75% and 95%, respectively. All SRPs underestimated the no/light rainfall (0–1 mm day−1) events. IMERG and PERSIANN-CCS exhibited poor performance with significant underestimation of the 1–2 mm day−1 rainfall class and overestimation of the 2–5 mm day−1 rainfall class. Our results not only demonstrate the superiority of different products at different elevations but also provide suggestions for further improvement of the SRPs, especially for complex terrains.