关键词: 再分析降水资料; ERA5; CFSR; 组合校正法; 长江中下游地区;

Abstract: In order to make up for the partial lack of observation data from stations in the middle and lower reaches of the Changjiang River, we explored the applicability of the reanalysis dataset and evaluated the accuracy of the ERA5 and CFSR reanalysis precipitation datasets in time and space.Then we established a multi-index quantitative comprehensive evaluation system including correlation coefficient, relative deviation, root mean square error and Kling Gupta coefficient, and proposed a correction method(C-AR) that combines correction coefficient method and autoregressive model.Finally, we compared C-AR correction method with single correction coefficient method, AR model, and the combined correction method of correction coefficient method and nearest neighbor sampling method(C-KNN) to explore the correction effect of C-AR combined correction method.The results show that:(1) ERA5 and CFSR are consistent with the measured precipitation data in terms of the annual and seasonal scales of precipitation trend changes and the precipitation distribution rules during the year.(2) Both ERA5 and CFSR have positive deviations in strong precipitation areas and negative deviations in weak precipitation areas.(3) C-AR combined correction model can not only correct the datasets in magnitude, but also improve the correlation between the dataset and the measured data.The model can comprehensively improve the accuracy of the dataset from many aspects and improve the applicability of datasets in the middle and lower reaches of the Changjiang River, which is significantly better than the correction coefficient method, the AR model and the C-KNN combined correction method.

Key words: reanalysis precipitation data; ERA5; CFSR; combined correction method; middle and lower reaches of the Changjiang River;