The Use of Geopotential Heights for Great Lakes Vertical Datum

摘要

Engineers leveling procedures for construction can assume that the earth is flat, but high precision geodetic levels are subject to the influences of the spheroidal figure of the earth and the variation of gravity with latitude. These effects can be calculated, and corrections applied to obtain either orthometric elevations or dynamic heights. The national level net is orthometric but a dynamic height system is used for the Great Lakes. A system of geopotential heights based on observed gravity instead of calculated gravity is suggested. (Author)