Dear Karl > I seem to recall that the normal to a geoid surface does not in > general point in the same direction as the normal to the ellipsoid > surface at the same place. If that is true, would that be added > justification for giving different standard names to heights > relative to those surfaces?
Jim made a related useful comment the other day: > The heights above > the datum can be orthometric (normal to the datum surface at the point) or > geodetic (normal to the ellipsoid). If your vertical datum is an ellipsoid, > then the two types of heights are the same. If you are using a > non-ellipsoidal vertical datum, you are probably going to report orthometric > heights ... > orthometric (normal to the geoid), geodetic (normal to the ellipsoid), and > geocentric (relative to the ellipsoid, but not normal to it). "Geometric" is also used but not in Jim's list. I wasn't aware of this kind of distinction and I suppose that relevant standard_names should say orthometric_height, geodetic_height, etc. instead of height, for use in cases where the distinction is important. Presumably so far no-one has required this additional precision. Best wishes Jonathan _______________________________________________ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
