我国高分辨率降水融合资料的适用性评估

Analyses of High-Resolution Merged Precipitation Products over China

利用国家气象信息中心研制的全国30000多个地面自动站降水与CMORPH(Climate Prediction Center Morphing technique)卫星反演降水融合而成的融合降水产品,分析了融合降水平均偏差和均方根误差的时空分布特征,探讨了不同降水量级以及站点稀疏区和密集区的融合效果,结果表明:融合降水的平均偏差和均方根误差量值均较卫星反演降水有显著减小,随时间的变化幅度不大且误差的区域性差异减弱;融合降水不同量级降水日数分布接近于地面观测降水,虽高估了雨强小于等于4mm/d的降水,低估了大于4mm/d高值降水,但同一量级下的误差比卫星反演降水大幅减小,且随着降水强度的增加改善效果明显;站点密集区的融合降水值主要是取决于地面观测降水;站点稀疏区在没有站点分布时,融合降水值主要取决于卫星反演降水,但随着站点个数增加,地面观测降水在融合降水中所占比重逐渐增大,且超过了卫星反演降水的作用。可见融合降水充分有效利用了地面观测降水和卫星反演降水各自的优势,融合效果明显。

On the basis of the merged precipitation observed by automatic meteorological stations and retrieved by the CMORPH （Climate Prediction Center Morphing technique） satellite, the merged precipitation product at temporal and spatial resolutions of 1 h and 0.1 ° （lat） × 0.1°（lon）, respectively, is developed by the National Meteorological Information Center. The quality of the product is assessed in terms of the mean error and root-mean-square error in the temporal-spatial distribution, the accuracy at different precipitation rates, and the merging effect in areas sparsely and densely covered by stations. The results indicate that （1） the regional mean error and root-mean-square error for the merged product decreased remarkably, and the extent of the change over the temporal-spatial distribution is weakened, although this trend is weaker in winter than in summer; （2） the merged precipitation presents a distribution of daily rainfall rates very close to that obtained by gauge analysis. Although the merged product overestimates light rains and underestimates heavy rains, both the mean error and root-mean-square error of the merged product are smaller than those of CMORPH in the same precipitation order, and the quality is improved further as the precipitation order increases; （3） In sparsely covered areas where there is no station, the merged product is controlled mainly by CMORPH. As the gaugenumber increases, however, the gauged-based precipitation plays a more important role than CMORPH. In contrast, in densely covered areas, the merged product is controlled mainly by the gauged-based precipitation. In summary, the merged product effectively takes advantage of the gauge observations and the product of the CMORPH satellite.