4种再分析月降水数据在内蒙古地区的适用性分析

利用1981—2020年气象台站的实测降水数据，对CRA40、ERA5、JRA55和MERRA2这4种再分析月降水数据在内蒙古地区的降水分布特征，与实测降水的相关性和误差进行分析。结果表明：(1)内蒙古地区4种再分析降水数据的空间分布与台站降水基本一致，误差分析表明CRA40与MERRA2的数据质量较高，ERA5次之，而JRA55数据质量相对较差。(2)CRA40和MERRA2在1983—1986年存在明显的降水低估，ERA5在2005年之后的内蒙古中东部出现明显的降水低估，JRA55在115°E以东存在明显降水高估，在115°E以西则以降水低估为主。(3)4种再分析月降水数据的年内最大均方根误差和绝对误差均集中在6—8月，与台站降水相关系数的年内最小值均出现在7月，内蒙古夏季汛期是再分析降水误差产生的主要时段。

Applicability analysis of four reanalysis monthly precipitation data in Inner Mongolia

Based on observed precipitation data in 1981-2020 from meteorological stations, the distribution of 4 reanalysis datasets, namely CRA40, ERA5, JRA55 and MERRA2 of the monthly precipitation in Inner Mongolia as well as their correlation with and error from observed precipitation data were analyzed. According to the results, (1) in Inner Mongolia, the spatial distribution of the 4 reanalysis datasets is basically consistent with precipitation data from the stations; error analysis indicates higher data quality of CRA40 and MERRA2, followed by ERA5, and JRA55 the poorest; (2) CRA40 and MERRA2 show a significant underestimation of precipitation in 1983-1986; ERA5 shows a significant underestimation of precipitation after 2005 in middle and eastern Inner Mongolia; JRA55 shows significant overestimation of precipitation in the area east of 115°E and mostly underestimation of precipitation in the area west of 115°E; (3) both maximum root-mean-square error (RMSE) and absolute error of the 4 reanalysis datasets of monthly precipitation within a year are concentrated in June-August, and the minimum coefficient of correlation with precipitation at the stations in July; reanalysis error is mostly found in the summer flood season of Inner Mongolia.