A Study on Tropospheric Delay Corrections in GPS Processing

• Main Authors: Jyh-Chung Liu, 劉至忠
• Other Authors: Chun-Sung Chen
• Format: Others
• Language: zh-TW
• Published: 1994
• Online Access: http://ndltd.ncl.edu.tw/handle/73247052692315667094

碩士 === 國立交通大學 === 土木工程研究所 === 82 === The tropospheric delay can be divied into the "dry" delay and the "wet" delay, owing to the wet term is more spatially and temporal varying than the dry term, thus is more difficult to model from surface meteorological data. The infiuences on GPS baseline result can be divied into two classes, the abso- lute and the relative tropospheric biases. The relative tropo- spheric biases introduce the height''''s biases into GPS baseline result, and is bigger than the absolute term in GPS relative positioning. Hence, the precision in height is 2-3 times the horizontial on Global Positioning System. Many troposphere models had been proposed, and different model in different GPS processing software. Which model will better fit in different case, and which order of precision in ifferent model, it is the aims in our study. We choose two baseline in different length and height from continuous-moni- toring GPS stations in the the Insititude of Earth Sciences, Academia Sinica. Three models for the troposphere,Saastamoinen、Modified Hopfield、Essen-Froome, will be tested using meteo data of observed and extrapolated from standard meteo model, and analyze the parameters estimated method for the tropo- spheric delay. Basically, the model of Saastamoinen and Modified Hopfield are almost identical. Using surface meteo data wwill get a better accuracy result in longer baseline; The Essen-Froome''''s model is more suitable in larger height difference''''s baseline. We obtain an magnitude of about 2cm in GPS height''''s precision by using parameters with observed meteo data to absorb the residual error of tropospheric delay.