利用ERA5资料进行桂林地区GNSS水汽反演精度分析

由于桂林地区地基GNSS站并未配置气象传感器,致使大量GNSS观测数据无法在大气水汽（PWV）监测中发挥作用.针对这一情况,本文将欧洲中期天气预报中心（ECMWF）最新发布的ERA5再分析资料中测站处的气压和温度气象数据加入到GNSS水汽反演中,并将反演结果与利用地面气象站反演的GNSS水汽做对比,以此评估ERA5在桂林地区反演GNSS水汽的精度和适用性.结果表明：1）以桂林地区2017年10个地面气象站的实测气压和温度数据为参考值,ERA5地表气压和温度的年均偏差分别为-0.35 hPa和0.86 K,年均均方根误差（RMSE）分别为0.65 hPa和1.66 K,该精度可用于GNSS水汽反演;2）以2017年6—7月GNSS利用地面气象站反演的PWV为参考值,ERA5反演的GNSS PWV的偏差和RMSE分别为0.17 mm和0.35 mm,且两者具较好的相关性和一致性.由此表明,ERA5地表温压产品可应用于桂林地区GNSS水汽反演,这些研究结果可为桂林地区的GNSS水汽反演及数据源的选用提供重要的参考依据.

Accuracy of ERA5 reanalysis data in retrieving GNSS precipitable water vapor over Guilin

Guilin''s ground-based GNSS station cannot be fully exploited in Precipitable Water Vapor (PWV) monitoring,owing to its omission of meteorological sensors.Here we use the pressure and temperature data from ERA5 reanalysis as well as from Guilin''s ground meteorological stations to retrieve the GNSS PWV,so as to evaluate the accuracy and applicability of ERA5 in GNSS PWV retrieval in Guilin.The results show that referenced with data of Guilin''s 10 ground meteorological stations in 2017,the ERA5 data of surface pressure (annual bias:-0.35 hPa,annual RMSE:0.65 hPa) and temperature (annual bias:0.86 K,annual RMSE:1.66 K) are accurate enough for GNSS PWV retrieval.As for the GNSS PWV retrieval results,the ERA5 approach has an average bias of 0.17 mm and RMSE of 0.35 mm,which is well correlated and consistent with meteorological station approach.The above results validate the accuracy and applicability of ERA5 surface temperature and pressure products in GNSS PWV retrieval in Guilin,and provide reference for GNSS PWV retrieval and data selection in other regions.