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How to compute orthometric altitudes

E.E. Klingelé

Abstract: 

In countries with a very rugged topography, the orthometric altitudes are better adapted than other scientific altitudes, particularly for the interpolation of the geoid between computation points. The computation of this kind of altitude is, however, complicated because of the unknown mean gravity values along the vertical. We propose a method for computing the mean gravity value along the vertical, joining measurement points and the geoid allowing us to compute the orthometric altitude in a very simple way. This method is based on the prolongation of gravity anomalies between general surfaces. We present a test profile for the Swiss Alps which shows an accuracy better than 0.5 mGal in the determination of gmean.