On the accuracy of modified Stokes's integration in high-frequency gravimetric geoid determination |
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| Authors: | P Novák P Vaníc˘ek M Véronneau S Holmes W Featherstone |
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| Institution: | (1) Department of Geodesy and Geomatics Engineering, University of New Brunswick, Fredericton, Canada E3B 5A3 e-mail: pnovak@ucalgary.ca; Tel.: +1 403 617 9157; Fax: +1 403 284 1980, CA;(2) Geodetic Survey Division, Natural Resources Canada, 615 Booth Street, Ottawa, Canada K1A 0E9, CA;(3) School of Spatial Sciences, Curtin University of Technology, GPO BOX U1987, Perth WA 6845, Australia, AU |
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| Abstract: | Two numerical techniques are used in recent regional high-frequency geoid computations in Canada: discrete numerical integration
and fast Fourier transform. These two techniques have been tested for their numerical accuracy using a synthetic gravity field.
The synthetic field was generated by artificially extending the EGM96 spherical harmonic coefficients to degree 2160, which
is commensurate with the regular 5′ geographical grid used in Canada. This field was used to generate self-consistent sets of synthetic gravity anomalies and
synthetic geoid heights with different degree variance spectra, which were used as control on the numerical geoid computation
techniques. Both the discrete integration and the fast Fourier transform were applied within a 6∘ spherical cap centered at each computation point. The effect of the gravity data outside the spherical cap was computed using
the spheroidal Molodenskij approach. Comparisons of these geoid solutions with the synthetic geoid heights over western Canada
indicate that the high-frequency geoid can be computed with an accuracy of approximately 1 cm using the modified Stokes technique,
with discrete numerical integration giving a slightly, though not significantly, better result than fast Fourier transform.
Received: 2 November 1999 / Accepted: 11 July 2000 |
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| Keywords: | : Geoid determination Stokes's integration Fast Fourier transform |
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