IMERG和TMPA降水产品在夏季中国中东部的检验

Evaluation of IMERG and TMPA Precipitation Datasets over Summer Mid-Eastern China

基于500个国家站雨量计的观测,从时空分布、不同地形条件、不同等级的降水强度及日变化角度,对比评估了2014-2016年夏季多星集成降水产品TMPA和IMERG在中国中东部的适用性。研究结果表明,与雨量计相比.TMPA和IMERG降水产品能较好地反映夏季中国中东部逐日降水量的变化规律,IMERG的平均误差更小。IMERG降水产品的日平均降水量与雨量计的相关性更高,相关系数超过0.9,而TMPA仅为0.8。在中国中东部的平原和山区,IMERG降水产品对弱降水(<4 mm·d-1)强度和弱降水频次的表征能力,较TMPA降水产品有明显的改善;但IMERG降水产品对山区的强降水频次的探测较TMPA降水产品改进有限。从日变化来看,TMPA降水产品明显低估早晨的降水强度和降水频次,且高估了午后的降水强度和降水频次。IMERG降水产品作为高时空分辨率的准全球降水资料,在中国中东部有较高的精度,未来可应用于气象和水文模式中。

Based on the observations from 500 quality-controlled rain gauges,the applicability of the tropical rainfall measuring mission(TRMM) multi-satellite precipitation analysis(TMPA) and integrated multi-satellite retrievals for global precipitation measurement(GPM) mission(IMERG) products to the precipitation in mid-eastern China during the summer of period 2014-2016 was analyzed,from the aspects of spatio-temporal distribution patterns,regional factors,rainfall intensities,and diurnal cycles.Statistical analysis showed that TMPA and IMERG have the similar daily variations of rainfall compared to gauge observations,and the mean errors are much smaller for IMERG.IMERG exhibits much stronger linear correlations(>0.9) with rain gauge observations than TMPA(0.8) at the daily scale.IMERG shows superior skill in estimating light rainfall(<4 mm·d-1) and detecting light precipitation events,compared with TMPA over both plain and mountain regions.However,no clear improvement is found in detecting heavy rainfall events over mountain regions.For precipitation diurnal cycles,TMPA underestimates the early morning rain intensity and rain frequency,but overestimates those in the late-afternoon.As a high spatiotemporal precipitation dataset,IMERG performs well over mid-eastern China,and can be applied in meteorological and hydrological models in the future.