The Geoid Height Calculator calculates a geoid undulation at a point whose latitude and longitude is specified. The program is designed to use the potential coefficient model EGM96 and a set of spherical harmonic coefficients of a correction term.
The correction term is composed of several different components, the primary one being the conversion of a height anomaly to a geoid undulation. The principles of this procedure were initially described in the paper: Use of Potential Coefficient Models for Geoid Undulation Determination Using a Spherical Harmonic Representation of the Height Anomaly/Geoid Undulation Difference by R.H. Rapp, Journal of Geodesy, 1996.
This program is designed to be used with the constants of EGM96 and those of the WGS84(G873) System. The undulation will refer to the WGS84 ellipsoid. This calculator uses the order 360 spherical harmonics file from EGM96 and using the F477.F routine as described on this page: NGA/NASA Geoid Height File. We are not using an interpolation method.
Specific details of the undulation computation will be found in the joint project report describing the development of EGM96. This program is a modification of the program described in the following report: A Fortran Program for the Computation of Gravimetric Quantities from High Degree Spherical Harmonic Expansions, Richard H. Rapp, Report 334, Department of Geodetic Science and Surveying, The Ohio State University, Columbus, 1982. This program was put in this form in December 1996. RHRAPP.F477.NONLY
Our geoid height calculator uses the order 360 spherical harmonics file from EGM96 and using the F477.F routine as described on this page: NGA/NASA Geoid Height File. We are not using an interpolation method.
Last modified: Tuesday, 07-Jul-2020 21:30:41 UTC