多种再分析地面气温资料在江西省的适用性

Applicability Assessment of Surface Air Temperature from JRA55,ERA-Interim,ERA5 and MERRA2 Reanalysis Products over Jiangxi Province

为评估不同再分析地面气温资料的适用性和模拟精度,采用双线性内插法将JRA55、ERA-Interim、ERA5和MERRA2等再分析地面气温资料降尺度至气象观测站,评估其对实测气温的平均态(平均偏差、均方根误差、相关性分析)、趋势态(年际趋势)和极端态(高温日数、低温日数)的再现能力。通过在江西省的对比分析,结果表明:(1)利用邻近格点气温和高度值计算的逐时气温垂直递减率具有合理的波动范围以及季节性周期,适用于复杂地形下逐时再分析资料的内插订正;(2)订正后JRA55地面气温资料的均方根误差最小,MERRA2其次,ERA-Interim和ERA5最大;(3)从气温年际变化趋势来看,JRA55、ERA-Interim和ERA5增温速率与实测值较为一致,且JRA55对增温中心的刻画更优;(4)4种再分析资料均能再现高、低温日数的年际波动,但JRA55在量级上描述最优。综上,再分析地面气温资料的适用性JRA55>ERA-Interim>ERA5>MERRA2,JRA55再分析资料能较好地再现气温实际观测资料。

In order to evaluate the performance of reanalysis surface temperature over Jiangxi Province,the gridded temperature data of the JRA55,ERA-Interim,ERA5 and MERRA2 reanalysis models during1980-2017 is topographically modified and interpolated to the station level by the bilinear interpolation method,to examine the applicability over observed temperature in terms of mean-state deviations(bias,root mean square error and correlation analysis),annual trend and extreme temperature events(the number of high/low temperature days).The results show that the lapse rate of air temperature calculated in the study has a reasonable range and seasonal cycle,and is suitable for the topographical correction for hourly data interpolation.Based on the topographically modified results,JRA55 has the lowest bias and root mean square error,followed by MERRA2,ERA-Interim and ERA5.As for the tendency,JRA55,ERA-Interim and ERA5 are consistent with observation in magnitude,while JRA55 has better capacity in capturing the spatial distribution of the warming.In the perspective of extreme temperature events,the four set of reanalysis data can reproduce the annual fluctuations,but only JRA55 shows closest magnitude to the observation.As a conclusion,the applicability is:JRA55>ERA-Interim>ERA5>MERRA2.