The purpose of this paper is to present the development and evaluation of
a new gravimetric geoid model (GARR98) for Canada and parts of the U.S., created
in the Dept. of Geomatics Engineering at the University of Calgary. The
methodology applied for the computation of the new geoid, and the data types that
were used, are discussed. GARR98 uses the most current databases available for
Canada, namely, new additional surface gravity data, high resolution DEM model,
and a more accurate geopotential model (EGM96). Comparisons among the new
geoid, geopotential models (OSU91A and EGM96), the latest GSD95 Canadian
geoid model, and GPS/levelling data, are also presented. Absolute and relative
differences at 1300 GPS benchmarks are computed, on both national and regional
scales. These external comparisonsnreveal interesting information regarding the behavior
of the Canadian gravity field, the quality of the geoid models, and the achevable
accuracy in view of future GPS/levelling applications.