Data Processing And Analysis Of Water Vapor Detection Based On Beidou And GPS

The Ground-based GNSS meteorology is a technology for detecting the atmospheric water vapor with the navigation satellite systems.which was proposed in the 1990s.The high-precision atmospheric water vapor data is required for meteorological services.With the growing maturity of GPS meteorological research,the application of BeiDou navigation satellite system of China is developing.The China Meteorological Administration is committed to promoting the application of the BeiDou navigation satellite system in detection of water vapor.In this paper,based on the Crustal Movement Observation Network of China and the BeiDou Ground-based Augmentation System,the experiments GPS/PWV and BeiDou/PWV are carried out respectively by using GAMIT and PANDA software to analyze the method,accuracy and annual variation of water vapor inversion by GNSS.This article studies as follows to show:In this paper,the observed data of GPS were processed by using the GAMIT software and the PWV is retrieved respectively by using the measured and predicted ephemeris files downloaded from IGS website,and the highest accuracy of IGF is used as the standard to determine the impact of the IGU on the PWV error.The results show that the orbit error of the measured and predicted IGU ephemeris is 4.5cm,resulting in PWV error of about 0.09mm.The mean square error of the PWV retrieved by the measured and predicted IGU ephemeris is less than 0.3mm,and the average deviation is not more than 0.06mm Moreover,the correlation coefficient is 99%,which indicates that the measured PWV and forecast PWV have a great consistency on the changing trend.Based on the IGF,the mean square error of atmospheric precipitation is about 0.16mm and 0.327mm by using the measured and predicted of IGU ephemeris respectively,which has little effect on PWV results.Therefore,the IGU ephemeris can meet the requirement of GPS NRT water vapor remote sensing.Based on the principle of ground-based GPS measurements for water vapor,the temporal variation of GPS/PWV and its spatial distribution in the typical months are analyzed.The results show that GPS/PWV presented an obvious seasonal distribution,which increased rapidly from March to May,and reached the maximum value of 80mm during June and August;while it decreased during September to November,with the minimum value of 30mm in winter.The daily variation of the GPS/PWV exhibited a certain cycle,the maximum and minimum appeared at about 20:00 pm and 08:00 am,respectively.The water vapor was concentrated in central China,southern China and eastern China in the typical months,and small variations were recorded in the rest of the region.Moreover.PWV decreased with the increase of latitude and decrease of longitude in typical months.At present,there are three kinds of water vapor patterns of BeiDou,GPS and GPS+BD in BeiDou Ground-based Augmentation System,which are compared with sounding and GPS data at the same site.The results show that:(1)the data from the BeiDou ground-based augment system can be effectively used to retrieve the total vapor content of the atmospheric,which is basically consistent with the GPS and the sounding system,the average deviation is less than I mm.It has a certain indication of numerical forecast.(2)Compared with the GPS system,the mean square error of GPS/PWV and GPS+BD/PWV is less than 2mm,and the correlation coefficient is more than 97%,which indicates that the accuracy is similar to GPS system.However,the mean square error of BeiDou/PWV is 3mm-6mm,the relative deviation is 15%-20%,which shows that there is a certain difference of accuracy between BeiDou and GPS system.(3)Compared with the sounding system,the BeiDou/PWV has some inconsistent with the situation in the individual of time changes,which the mean square error is 2.14-6.12mm and the relative deviation is 15.32-20.84mm.Its errors may be due to factors such as the detection system errors,while the GPS+BD/PWV and GPS/PWV will be more stable.