中国区域ERA5-ZTD/PWV精度评估与台风事件响应研究

Accuracy Assessment of ERA5-ZTD/PWV and Response of Typhoon Events in China

再分析数据能够提供多种历史气象数据同化产品,为了评估欧洲中期天气预报中心的最新一代ERA5再分析数据集估计的天顶对流层延迟(Zenith Tropospheric Delay,ZTD)和大气可降水量(Precipitable Water Vapor,PWV)产品在中国区域的精度,利用2017—2019年中国区域内14个全球导航卫星系统地面监测站和89个探空站反演的ZTD和PWV数据分别对ERA5-ZTD和ERA5-PWV精度进行了评估。结果表明,除青藏地区的站点外,ERA5-ZTD的精度分布较为均匀,平均Bias、RMSE和STD分别为-6.3 mm、19.3 mm和17.5 mm;ERA5-PWV的精度分布呈现西部内陆高和东南沿海低的趋势,平均Bias、RMSE和STD分别为0.3 mm,2.9 mm和2.7 mm。此外,在研究2019年“利奇马”台风期间ZTD和PWV的时空分布中,提出了使用水汽到达时间差的方法定量估计台风的水汽移动速度。得到台风期间ZTD和PWV具有相同的空间分布规律,且移动方向与台风的移动路径方向是一致的,估计的水汽平均移动速度为12.4 km/h,与台风的平均移动速度16.1 km/h非常接近。因此,ERA5-ZTD/PWV在中国区域内具有较高的精度,ZTD和PWV可作为重要气象因子为台风的预警预报研究提供重要参考。

Reanalysis data can provide a variety of historical meteorological assimilation products.To evaluate the accuracy of zenith tropospheric delay(ZTD) and precipitable water vapor(PWV) derived from ERA5 datasets of the European Centre for Medium-Range Weather Forecasts over China,the ZTD and PWV derived from the 14 ground Global Navigation Satellite System stations and 89 sounding stations in China during 2017—2019 are used to test the accuracy of ERA5-ZTD and ERA5-PWV.The results show that the accuracy distribution of ERA5-ZTD is uniform except for the sites in Qinghai-Tibet region,and the mean Bias,RMSE and STD of ERA5-ZTD are-6.3 mm,19.3 mm and 17.5 mm,respectively.The accuracy distribution of ERA5-PWV shows a trend of higher accuracy in the western interior and lower accuracy in the southeast coast,with the mean Bias,RMSE and STD of 0.3 mm,2.9 mm and 2.7 mm,respectively.In addition,the temporal and spatial distributions of ZTD and PWV during the super typhoon Lekima's period in 2019 are studied,and a method based on arrival time difference of water vapor is proposed to quantitatively estimate the water vapor moving velocity of the typhoon.The results show that spatial distributions of ZTD and PWV are similar during the typhoon's period,and the moving directions of ZTD and PWV are both consistent with the direction of the typhoon's path.The estimated mean moving speed of water vapor is 12.4 km/h,which is very close to the average moving speed of typhoon 16.1 km/h.The above studies fully show that ERA5-ZTD/PWV has a high accuracy in China,and ZTD and PWV can be used as important meteorological factors to provide important reference value for typhoon early warning and forecast research.