Colorado - USA (ColFFTDB-CGS2019)
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Authors: M. Véronneau, J. Huang
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Created: 2019
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Resp: J. Huang |
Description:
The ColFFTDB2019 gravimetric quasi-geoid and geoid models have been computed by the Canadian Geodetic Survey (CGS), Nature Resources Canada. They have been worked out in the frame of the International Association of Geodesy Joint Working Group 2.2.2 "The 1 cm geoid experiment" and the so called "Colorado experiment". The area covered by the models is 110°W ≤ longitude ≤ 102°W, 35°N ≤ latitude ≤ 40°N with a grid spacing of 1' in both latitude and in longitude. The solution is based on the Stokes-Helmert method, which is used with the degree-banded Stokes kernel modification (Huang and Véronneau, 2013). A band-wise spectral scheme is developed to combine the global model, airborne and surface gravity data, contributing to low-, medium- and high-degree bands of the geoid, respectively. In particular, the global gravity model provides entirely the low-degree band up to degree 150 from where it goes into transition with the surface gravity data up to degree 210. The surface gravity data complete the geoid frequencies up to degree 10800 with complement information from SRTM 3″ digital terrain model. As for the GRAV-D airborne gravity data, they provide corrective values directly to the geoid model, contributing between degrees 210 and 1400 with smooth transition at each end. The geoid computation is performed by Fast Fourier Transform (FFT) numerical integration. A quasi-geoid model is then approximately derived at GPS/leveling benchmarks for the sole purpose of comparisons with other models computed in the framework of the "Colorado experiment". The accuracy of the quasi-geoid and geoid models, when compared against GSVS17 GPS/leveling, is equal to 1.8 cm and 2.0 cm, respectively.
Reference:
J. Huang, M. Veronneau (2013). Canadian gravimetric geoid model 2010. Journal of Geodesy, 87(8), pp. 771-790. DOI: 10.1007/s00190-013-0645-0
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