COSMIC-2近实时廓线反演对流层延迟及其质量分析

Quality analysis of retrieval zenith tropospheric delay from COSMIC-2 near real-time radio occultation profile

为了进一步提高全球大气探测和极端天气预报的精度,提出一种气象、电离层与气候星座观测系统2代(COSMIC-2)近实时廓线反演对流层延迟方法:指出随着气象、电离层与气候星座观测系统2代(COSMIC-2)掩星探测深度的加深,通过掩星手段为地表全球卫星导航系统(GNSS)观测站提供近实时先验天顶对流层延迟(ZTD)产品成为可能;采用COSMIC-2掩星Level 2近实时产品wetPf2大气湿度廓线获取掩星ZTD,并以欧洲中期数值天气预报中心第五代再分析资料(ERA5)作为参考,分高程、纬度、季节评估其反演精度。结果表明,COSMIC-2掩星反演天顶对流层延迟ZTD整体精度较高,10 km高程以下全球定位系统(GPS)信号反演ZTD精度较格洛纳斯卫星导航系统(GLONASS)信号更优;掩星反演ZTD精度随高程增加而提升,在0~1 km高程范围内精度最低,均方根(RMS)分别为11.33 mm(GPS)、11.54 mm(GLONASS);中低纬度区域(25°N—35°N)反演ZTD精度低于低纬(15°N—25°N)和中纬(35°N—45°N)区域,其中中纬区域精度最高,RMS分别为4.74 mm(GPS)、4.70 mm(GLONASS);掩星反演ZTD精度同样受季节影响,GPS/格洛纳斯全球卫星导航系统(GLONASS)双模信号均在夏季反演精度最差,冬季反演精度最高,冬季RMS分别为4.15 mm(GPS)、4.18 mm(GLONASS)。

In order to further improve the accuracy of global atmospheric detection and extreme weather forecasting,the paper proposed a retrieval method of zenith tropospheric delay from the constellation observing system for meteorology ionosphere and climate-2(COSMIC-2)near real-time radio occultation profile:it was pointed that with the deepening of COSMIC-2 radio occultation(RO)detection depth,it became feasible to provide priori near-real-time zenith tropospheric delay(ZTD)products for ground-based global navigation satellite system(GNSS)observation stations through radio occultation ways;then,the retrieval ZTD obtained thro ugh the near-r eal-time COSMIC-2 Level 2 product wetPf2 was evaluated with the fifth reanalysis data of European Centre for Medium-Range Weather Forecasts(ERA5)as a reference,and the evaluation was conducted considering elevations,latitudes and seasons.Results showed that the overall accuracy of retrieval ZTD using COSMIC-2 would be high,and the overall accuracy for global positioning system(GPS)signal would be better than that of global navigation satellite system(GLONASS)signal under 10 km elevation;the accuracy of retrieval ZTD could be improved with increasing elevation,with the lowest accuracy in the range of 0~1 km elevation,where root mean square(RMS)would be 11.33 mm(GPS)and 11.54 mm(GLONASS);in the mid-low latitude range(25°N-35°N),the retrieval ZTD accuracy would be lower compared to low latitudes(15°N-25°N)and mid latitudes(35°N-45°N)regions,with the highest accuracy in the mid-latitude region,where RMS would be 4.74 mm(GPS)and 4.70 mm(GLONASS);moreover,the retrieval ZTD could be also affected by seasonal variations,with both GPS and GLONASS signals showing the worst accuracy in summer and the highest accuracy in winter(RMS:GPS 4.15 mm,GLONASS 4.18 mm).