Abstract
Owing to their advantages of wide coverage and high spatiotemporal resolution, satellite precipitation products (SPPs) have been increasingly used as surrogates for traditional ground observations. In this study, we have evaluated the accuracy of the latest five GPM IMERG V6 and TRMM 3B42 V7 precipitation products across the monthly, daily, and hourly scale in the hilly Shuaishui River Basin in East-Central China. For evaluation, a total of four continuous and three categorical metrics have been calculated based on SPP estimates and historical rainfall records at 13 stations over a period of 9 years from 2009 to 2017. One-way analysis of variance (ANOVA) and multiple posterior comparison tests are used to assess the significance of the difference in SPP rainfall estimates. Our evaluation results have revealed a wide-ranging performance among the SPPs in estimating rainfall at different time scales. Firstly, two post-time SPPs (IMERG_F and 3B42) perform considerably better in estimating monthly rainfall. Secondly, with IMERG_F performing the best, the GPM products generally produce better daily rainfall estimates than the TRMM products. Thirdly, with their correlation coefficients all falling below 0.6, neither GPM nor TRMM products could estimate hourly rainfall satisfactorily. In addition, topography tends to impose similar impact on the performance of SPPs across different time scales, with more estimation deviations at high altitude. In general, the post-time IMERG_F product may be considered as a reliable data source of monthly or daily rainfall in the study region. Effective bias-correction algorithms incorporating ground rainfall observations, however, are needed to further improve the hourly rainfall estimates of the SPPs to ensure the validity of their usage in real-world applications.
Highlights
IntroductionAccurate and high-resolution precipitation data are crucial in different fields such as weather forecast, disaster preparation and prevention, and water resource management [3,4]
Precipitation is an important component of the hydrological cycle [1,2]
We aim to evaluate the performance of a total of five satellite precipitation products (SPPs) in the SRB, including the Early, Late, and Final runs of the IMERG Version 6 (V6) products (0.1◦ × 0.1◦ and 30-min interval), and the near-real-time and post-processed runs of the TRMM Multi-satellite Precipitation Analysis (TMPA) version 7 (V7) products (0.25◦ × 0.25◦ and 3-hour interval)
Summary
Accurate and high-resolution precipitation data are crucial in different fields such as weather forecast, disaster preparation and prevention, and water resource management [3,4]. The quality and resolution of precipitation inputs can significantly affect the performance of various hydrological, climatic, and atmospheric models [5]. Weather radar products can provide rainfall observations over a wide region [7], they are subjected to both random and systematic errors [8,9,10,11]. Random errors could arise from the sub-grid horizontal and vertical variability of rainfall and the noise of the radar hardware system, while systematic errors may originate from sources such as drifts in radar calibration constant, systematic variations in the reflectivity–rain-rate relationship, and strong gradients in the reflectivity profile [12]. The presence of complex topography may further amplify some of the error sources [13]
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