I finally get a chance to look like I might know something. Neiher Gravity nor the Geoid are "standardized." Witness that maps from some countries do not employ WGS-84. (Korea was this way. I am not sure whether they still are.) There are "best practices" documents, including some issued by standards organizations, but they are not "normative" standards. Data exchange standards, which are normative, require statement of the gravity model and its metadata employed. They also required statement of the time system and Earth Orientation Parameters (including the epoch of the Earth rotation model).
One reason that Gravity is no standardized is that different degrees of gravitational modeling are best for different problems. There is also a matter of internal consistency. When the data are sparse, high orders of approximation to gravitation, the geoid, or the atmosphere alias the sparse data, revealing numerical artifacts rather than real physics. At one point, I worked in a field that never grew much called "phenomelogical discrimination," discerning numerical artifacts from reality. It is precisely the ambiguity in definition, let alone application, that led to my involvement in the leap second issue. Dave Finkleman Senior Scientist Center for Space Standards and Innovation Analytical Graphics, Inc. 7150 Campus Drive Colorado Springs, CO 80920 Phone: 719-510-8282 or 719-321-4780 Fax: 719-573-9079 Discover CSSI data downloads, technical webinars, publications, and outreach events at www.CenterForSpace.com. *************** _______________________________________________ LEAPSECS mailing list [email protected] http://six.pairlist.net/mailman/listinfo/leapsecs
