| Summary: | 博士 === 國立中央大學 === 地球物理學系 === 82 === Results obtained in this study indicated that the internal
precision of ME5000 distance measuring system, is about
±(0.1+0.1‧D)mm, where D is distance in km. An uncertainty of
external precision in the absolute length system of light
speed, as indicated from a comparison of the EOM results with
Vaisala interference results - i.e., the most accurate method
of determining the baseline length. Furthmore, its stability
and accuracy has become the foundation for examining the
atmospheric refraction correction for a medium - range EDM in
the study. Due to long distance, the temperature, pressure and
relative humidity are normally taken at the ends of the line
during EDM. The averages of temperature, pressure and relative
humidity from endpoints measurments are used to represent the
true values along the wavepath length. As a consequence, the
errors may cause a great restriction for the accuracy of EDM.
This study, as based on the theory of atmospheric temperature
model of Angus-Leppan and Brunner (1980), primarilly aims at
analyzing the successive EDM data in Hsin Chu Medium-Range
baseline as well as proposing a more practical and suitable
temperature model for local area. Consequently, the error of
group refractive index can be reduced and the accuracy
improved. Furthermore, multi-layer atmospheric potential
temperature model based on Webb (1964) was included to evaluate
the additional correction when the elevation difference of EDM
line is over the Obukhov length. This could be of help to raise
the accuracy of EDM in Geodesy and the detection of crust
deformation in Geophysics.
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