How to Compute Geoid Undulations (Geoid Height Relative to a Given Reference Ellipsoid) from Spherical Harmonic Coefficients for Satellite Altimetry Applications

This document describes in a cookbook-fashion how to obtain geoid height at a given location on the Earth from spherical harmonic coefficients of a gravity model. The document is intended to aid ``the uninitiated oceanographer'' in constructing geoid undulations relative to a given reference ellipsoid, defined by semi-major axis and flattening parameter, to be used with satellite altimetry products.