Comprehensive evaluation and comparison of ten precipitation products in terms of accuracy and stability over a typical mountain basin, Southwest China

Reliable precipitation information is important for a multitude of scientific and operational applications. Openaccess gridded precipitation products (OGPPs) are important information sources owing to their spatiotemporal continuity and large-scale coverage. However, few studies have comprehensively compared the accuracies and stabilities of various OGPPs, particularly in mountainous basins. The key methodological challenges are how to quantitatively evaluate stability and how to rationally assemble accuracy and stability characteristics to determine the best product. To address these requirements and challenges, we propose a three-stage framework methodology based on typical statistical accuracy metrics, sample entropy, and an innovative decision support index. Subsequently, the framework was applied to comprehensively compare ten OGPPs. The comparison was conducted at the basin and point scales over the Chengbi River Basin (Southwest China), which is equipped with mountainous topography and 12 independent precipitation gauges. The results show that all OGPPs had high accuracy, but their performance was unstable. Meanwhile, all products tended to have lower accuracies but similar stabilities at higher altitudes. In addition, all OGPPs had better accuracy at the basin scale than at the point scale; however, there was no significant scale phenomenon in terms of stability. Multi-source fusion-type products (i.e., multi-source weighted-ensemble precipitation and China meteorological forcing dataset) tended to be more stable than other products while offering outstanding accuracy. Furthermore, regarding the assembly accuracy and stability characteristics, the multi-source weighted-ensemble precipitation and climate prediction center morphing method products exhibited the best comprehensive performance at the point and basin scales, respectively. This study provides an efficient methodology for OGPP comparisons and valuable guidance for precipitation product development and application.