| Summary: | 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.
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