The Theory And Research Of Atmosphere Affection To GPS Surveying

Wth the develoPmnt and aPplication of GPS, the research of errors of GPSbecomes more precise and scientific. AAnosphere refraction is a main error inGPS surveying. The error of atmosphere refraction mainly lies on the innerstfuCtue of inosphere and the SPatial relation of Station and satellite. Based onthe characteristic of atmosphere influence, the atmosphere affection to GPSsurveying is divided into the neuter atmosphere affection and the ionosPhereaffection. It is a cornrnon method for domestic and overseas researchers to use thetheory of driosphere propagation to establish the theory of aAnosphere refractionand the correcting model. In order to estabIish a more effective method fOrcorrecting, tWo kinds of atmoSPhere affection in GPS surveying are studied inthis paPeLThe main achievements of this paPer are as follows'l. The basic concept of troPospheric refraction is defined. It is reduced tospeed delny and inflecting delay. Thereinto, the speed delay is themajor error other than the inflecting delay. Only if When the satelliteelevation angle is less than l0 degree or the altitude of station is verylow the infiecting delay is taken into account. Othebose, the error wllincrease about l0cm.2. By analyzing and comparing differences betWeen the globalatriosPhere mode1 and the 1ocal atmosphere model, it is found that thecorrect is very deficient when the aAnosphere of the Qing-ZangTableland is corrected with the standard atmosphere model. TherefOre,by using meteorologic data of the Qing~Zang TabIeland, the locaIaAnosPhere refraction correction model of the Qing-Zang Tableland isPut rorwaru.3. Theories of atInosphere refraction and correcting methods areresearched systemically And differences and sensitivities of aIl kindsof zenith delays and projection functions are compared. Thus,temperature is regarded as the main factor to bring differences betweenzenith deIay models and there are some diff'erences between Proectionfunctions only when the satellite elevation angle is small.4. An estimation teclmique used fOr estimating the atmosphere affectionin GPS surveying is set uP. By comparing baseline repetition, it isllconcluded that the random estimation process is the best solution for calculating atmosphere refraction.5.Based on atmosphere forecasting mode, the theory of atmosphere correction is brought forward and a new method for correcting the atmosphere delay is attempted. And methods for application of GPS in meteology are studied, which provide new approaches for forecasting precinpitable water.6.The main affection of ionosphere to GPS is analyzed. Based on the main characteristic of group delay and phase delay or the primary characteristic of single frequency and double frequency, all kinds of techniques are discussed. Furthermore, the arithmetic of grid correction and its corrective precision in WAAS are studied.7.In DGPS, principles and methods for correcting ionosphere parameters of single frequency receiver are introduced. Analyzing from most ionosphere correction methods, we know that the essential characteristic of ionosphere correction is that it take advantage of the correlation of ionosphere. The degree of correlation determines user抯 total electron content. Besides, it is an effective way to use GPS to reflect relative changes of ionosphere.