以實測重力值進行正高改正對水準點高程影響之研究

Abstract

本研究著重於探討沿一水準測線利用實測重力值進行嚴密正高改正對水準點精確高程之影響。本文採用較一般傳統正高改正公式為嚴密且實用之公式計算正高改正之值，另外，亦針對一些傳統上使用但較不嚴密之正高計算公式採用同一條水準路線加以探討及比較。台灣地區一等水準網內某約90公里測段冰準點間之高程及重力資料將引以為例進行正高改正計算。由本文研究成果顯示在測試水準路線間某些具有較大高差及平均高程之水準點位間，當以實測重力值代入較嚴密正高改正公式以取代傳統正高改正公式時會產生較大之正高改正值，其量最大可達24公分左右。本文研究之成果對傳統水準測量點位高程之計算精確將有助益，應可提供世界大地測量學者專家們共同進一步研究。

This study concerns the effect of inclusion gravimetric observation to compute the rigorous orthometric correction, into a leveling route, along with an analysis of the impact of such inclusion on accurately height determination of these bench marks. In this paper, a rigorous and practical formula for the Computation of the orthometric correction has been adopted. In addition, some other traditional formulas to compute orthometric correction have also been discussed and compared. The leveling and gravimetric observations of 14 bench marks along a 90 km leveling route within the first order leveling network of Taiwan have been used as a test leveling route to compute the orthometric corrections and orthometric heights. The results obtained in this study show that bench marks which had a larger elevation difference and mean elevation within the test leveling route creates large orthometric correction when the conventional simplified formula was replaced by the rigorous formula, some orthometric corrections reach up to 24 cm. A surprising result was found from this study, and it indicated that rigorous orthometric correction plays an important role in computing the accurate height of the bench marks along the test leveling route.