北斗和GPS反演大气可降水量的对比分析

北斗地基增强系统是我国北斗卫星导航系统重要的地面基础设施,它可以获取高精度、高时间分辨率的水汽产品,满足数值预报、空间天气监测和预警业务的需求。本文利用2017年北斗地基增强系统中北斗单模、GPS单模和GPS+BD双模的数据资料,对同址的北斗气象站、GPS气象站和探空站反演大气可降水量进行对比分析,结果表明:(1)现行北斗地基增强系统所提供的数据,可以有效地用来反演大气柱总水汽含量,所得结果合理,平均偏差都小于1 mm,在变化上与GPS系统和探空系统基本一致,对数值预报有一定的指示作用;(2)与GPS系统相比,GPS单模/PWV和GPS+BD双模/PWV的均方差小于2 mm,相关系数均在0. 97以上,表明两者在反演PWV的精度上与GPS系统相当,而北斗单模/PWV的均方差为3～6 mm,相对方差达到了15%～20%,其精度与GPS系统还有一定的差距;(3)与探空相比,北斗单模在个别时次变化趋势上存在不一致的情况,其均方差为2. 14～6. 12 mm,相对方差为15. 32%～20. 84%,其误差可能是由于探测系统误差等因素造成的,而GPS+BD双模和GPS单模会更加稳定。

Comparison of Atmospheric Precipitable Water Vapor Retrieved by Beidou and GPS

The Beidou Ground based Augment System is the important infrastructure of the Beidou Satellite Navigation System. To obtain water vapor products with high precision and resolution is the demand for numerical forecasting, space weather monitoring and early warning services. This paper, using the data from three kinds of water vapor patterns of Beidou, GPS and GPS + BD in Beidou Ground based Augment System, combined with the radiosonde observation, makes detailed comparative analysis among Beidou, GPS and sounding systems. The results show that: (1) The data provided by the Beidou Ground based Augment System can be effectively used to retrieve the total vapor content of the atmospheric column, and the average deviation is less than 1 mm, which is basically consistent with the GPS and the sounding system and has some indication to numerical forecast. (2) Compared with the GPS system, the mean square error of GPS/PWV and GPS+BD/PWV is less than 2 mm, and the correlation coefficient is more than 97%, which indicates that the accuracy is similar to GPS system. However, the mean square error of Bei dou/PWV is 3-6 mm, and the relative variance is 15%-20%, which shows that there is a certain diffe rence of accuracy between Beidou and GPS system. (3) Compared with sounding system, the Beidou/PWV has some inconsistency with the situation in individual time changes, which the mean square error is 2.14-6.12 mm and the relative variance is 15.32%-20.84%. The errors may be due to factors such as the detection system errors, while the GPS+BD/PWV and GPS/PWV will be more stable.