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中国大陆IMERG和GSMaP小时降水产品适用性评估

Performance Assessment of Hourly Precipitation Products from IMERG and GSMaP over Mainland China

  • 摘要: 中国幅员辽阔,地形和气候类型多样,卫星反演降水产品在不同区域的适用性差别较大。基于国家气象观测站2019—2023年逐小时地面降水观测数据,首先分析了中国大陆区域IMERG(Integrated Multi-satellitE Retrievals for GPM)_V7(以下简称IMERG)和GSMaP(Global Satellite Mapping of Precipitation)_V8(以下简称GSMaP)两种卫星反演小时降水产品的分布特征,并采用定量和分类统计评估方法对比两种产品不同区域、不同月份及不同时段的误差特征,最后探讨了二者在不同天气背景下的适用性差异。结果表明:两种产品普遍高估弱降水事件频次、低估强降水事件频次,尤以GSMaP产品高估弱降水事件频次更明显,其平均小时雨强较地面观测一致偏弱,IMERG产品不同雨强等级频次分布更接近地面观测,其平均小时雨强整体较地面观测虽然同样偏弱,但在西北地区东部、西南地区等区域较地面观测偏强;两种产品对西南地区秋冬季绵阴雨及黄淮以北地区冬季降雪天气的晴雨判识能力均较低,其中,GSMaP产品较IMERG产品关键成功指数略高,与地面观测相关性也更强;二者在江南、江淮地区的春季降水及淮河流域秋季降水中的表现优于其他雨季,而对华南前汛期,尤其是午后至前半夜以暖区对流为主的降水,晴雨判识能力均较弱,误差显著增加。对比来看,IMERG产品在各主要雨季中表现更优,特别是在7—8月主汛期,得益于其较低的空报率,其关键成功指数显著高于GSMaP产品,相关性也较GSMaP产品更高。

     

    Abstract: Precipitation in China exhibits high diversity and significant regional differences, leading to considerable variability in the applicability of satellite-derived precipitation products. Using hourly surface observations from national meteorological stations (2019–2023), this study evaluates two hourly satellite products—IMERG_V7 (hereafter IMERG) and GSMaP_V8 (hereafter GSMaP)—over mainland China. Spatial patterns and error characteristics are compared across regions, months, and time periods using quantitative and categorical statistics, and applicability under different weather conditions is assessed.The result shows: both products overestimate light precipitation frequency and underestimate heavy precipitation, with GSMaP showing a stronger overestimation of light events and weaker mean intensities. IMERG more closely matches observed intensity distributions and is locally stronger in eastern Northwest and Southwest China. Both perform poorly for persistent autumn–winter rainfall in Southwest China and winter snowfall north of Huang–Huai, though GSMaP shows slightly higher critical success index (CSI) and correlation in these cases. Performance is better for spring rainfall in Jiangnan/Jianghuai and autumn rainfall in the Huai River Basin, but weaker for pre-flood season convection in South China. Overall, IMERG outperforms GSMaP in major rainy seasons, particularly July–August, due to a lower false alarm rate and higher CSI and correlation..

     

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