ABSTRACT: Large-scale agricultural production in North China makes the study of precipitation in this area vital. The performance of the Integrated Merged Multisatellite Retrievals for the Global Precipitation Measurement (IMERG) and the Climate Prediction Center morphing technique (CMORPH) precipitation products for 2015 was evaluated against daily precipitation data from 404 rain gauges in North China. Relative errors, correlation coefficients, Pearson’s chi-squared test values, and root mean square errors, as well as the probability of detection (POD), false alarm ratio, and critical success index, were used to analyze the accuracy of both IMERG and CMORPH precipitation products on daily, monthly, and seasonal timescales. The probability density function (PDF) was also considered. Overall, both products overestimated ground precipitation, especially in summer. Positive correlation coefficients between satellite-derived and rain-gauge monthly precipitation data were higher over plains and coastal areas, compared with plateau regions. The PODs of both IMERG and CMORPH data were highest in summer. The PODs of IMERG data were much higher than for CMORPH data in autumn. The PODs over coastal regions, plains, and plateaus at lower latitudes also were considerably better than over inland and plateau areas at higher latitudes. The precipitation products performed best over coastal areas, plains, and areas with high rainfall. Both CMORPH and IMERG products were prone to identifying non-rainy days as rainy days. They also overestimated light (0.1-9.9 mm d^-1) and moderate (10-24.9 mm d^-1) precipitation events, although the IMERG product was more sensitive to precipitation. Accordingly, we find that both of these satellite-derived precipitation products require further modification to enable them to substitute for gauge precipitation data in North China.

中文翻译：

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华北地区IMERG和CMORPH降水数据的精度分析

摘要：华北地区的大规模农业生产对该地区的降水研究至关重要。根据华北地区404个雨量计的每日降水数据，对2015年全球降水综合测量（IMERG）和气候预测中心变质技术（CMORPH）降水产品的合并多卫星综合性能进行了评估。相对误差，相关系数，皮尔逊卡方检验值和均方根误差以及检测概率（POD），误报率和关键成功指数均用于分析IMERG和CMORPH的准确性每日，每月和季节性时间尺度上的降水量产品。还考虑了概率密度函数（PDF）。总体而言，这两种产品都高估了地面降水，特别是在夏天 与高原地区相比，平原和沿海地区的卫星数据和雨量计的月降水量数据之间的正相关系数更高。夏季，IMERG和CMORPH数据的POD最高。秋季，IMERG数据的POD远高于CMORPH数据。低纬度沿海地区，平原和高原上的POD也比高纬度内陆和高原地区上的POD好得多。在沿海地区，平原和高降雨地区，降水产品表现最好。CMORPH和IMERG产品都倾向于将非雨天确定为雨天。他们还高估了光线（0.1-9.9 mm d 与高原地区相比，平原和沿海地区的卫星数据和雨量计的月降水量数据之间的正相关系数更高。夏季，IMERG和CMORPH数据的POD最高。秋季，IMERG数据的POD远高于CMORPH数据。低纬度沿海地区，平原和高原上的POD也比高纬度内陆和高原地区上的POD好得多。在沿海地区，平原和高降雨地区，降水产品表现最好。CMORPH和IMERG产品都倾向于将非雨天确定为雨天。他们还高估了光线（0.1-9.9 mm d 与高原地区相比，平原和沿海地区的卫星数据和雨量计的月降水量数据之间的正相关系数更高。夏季，IMERG和CMORPH数据的POD最高。秋季，IMERG数据的POD远高于CMORPH数据。低纬度沿海地区，平原和高原上的POD也比高纬度内陆和高原地区上的POD好得多。在沿海地区，平原和高降雨地区，降水产品表现最佳。CMORPH和IMERG产品都倾向于将非雨天确定为雨天。他们还高估了光线（0.1-9.9 mm d 秋季，IMERG数据的POD远高于CMORPH数据。低纬度沿海地区，平原和高原上的POD也比高纬度内陆和高原地区上的POD好得多。在沿海地区，平原和高降雨地区，降水产品表现最好。CMORPH和IMERG产品都倾向于将非雨天确定为雨天。他们还高估了光线（0.1-9.9 mm d 秋季，IMERG数据的POD远高于CMORPH数据。低纬度沿海地区，平原和高原上的POD也比高纬度内陆和高原地区上的POD好得多。在沿海地区，平原和高降雨地区，降水产品表现最好。CMORPH和IMERG产品都倾向于将非雨天确定为雨天。他们还高估了光线（0.1-9.9 mm d^-1）和中等（10-24.9 mm d ^-1）降水事件，尽管IMERG产品对降水更敏感。因此，我们发现这两个卫星降水产品都需要进一步修改，以使其能够替代华北地区的常规降水数据。