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  • 1
    Online Resource
    Online Resource
    New York, NY :Springer,
    Keywords: Geography. ; Physical geography. ; Electronic books.
    Description / Table of Contents: Symposium No. 106, Milan, Italy, June 11-13, 1990.
    Type of Medium: Online Resource
    Pages: 1 online resource (500 pages)
    Edition: 1st ed.
    ISBN: 9781461231042
    Series Statement: International Association of Geodesy Symposia Series ; v.106
    DDC: 525/.1
    Language: English
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  • 2
    Keywords: Gravity Congresses Measurement ; Global Positioning System Congresses ; Geoid ; Berechnung ; Geoid ; Berechnung ; GPS ; Earth (Planet) Congresses Figure ; Measurement ; Konferenzschrift ; Konferenzschrift 1990 ; Geoid ; Berechnung ; Geoid ; Berechnung ; GPS
    Type of Medium: Book
    Pages: XI, 500 S , Ill., graph. Darst., Kt
    ISBN: 0387974709 , 3540974709
    Series Statement: International Association of Geodesy Symposia 106
    DDC: 525/.1
    Language: English
    Note: Literaturangaben
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 54 (1963), S. 1-5 
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary The relations of the defining parameters of a geodetic system to the deflections of the vertical in this system given byVening Meinesz have been used in the computation of a best fitting ellipsoid. The data was that used byHayford in the computation of the resulting International Ellipsoid. Assuming the undulation (N 0) at Meades Ranch to be zero, the results are: a=6,378,194 m and l/f=299.9. This a is much nearer to modern values than that of the Internaitonal Ellipsoid. If a flattening of 1/298.24 is fixed andN 0=+3m,a=6,378,164 m which differs by one meter from a recent determination given byKaula.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical journal international 117 (1994), S. 0 
    ISSN: 1365-246X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: A gravimetric geoid undulation, on a 3’ x 3’ grid has been calculated in the Gulf Stream region: 30°≤φ≤ 45°, 278°≤λ≤ 318°. These undulations were calculated using two 360 potential coefficient models, land, ship and altimeter-derived gravity anomalies, and bathymetric data. Least-squares collocation and fast Fourier transform procedures were used with various data selection and gridding procedures. Results from five different undulation computations are described with comparisons made with synthetic geoid undulations along Geosat tracks in the region. the standard deviation of the undulation differences was ±14 cm when a cubic polynomial was used to model long-wavelength errors. A point verification of the geoid undulation at the laser tracking station on Bermuda was also made with a discrepancy (‘ground truth’ minus model undulation) of 40 cm, within the predicted standard deviation. the gravimetric geoid undulation was used to compute dynamic topography along Geosat tracks for comparison with existing estimates based on hydrographic data in the Gulf Stream region. the agreement between these two estimates is on the order of ±15 cm although the discrepancies can reach 60cm. the larger differences are usually associated with a location on a track that passes near a seamount where the gravity data may be inadequate to represent the high-frequency variations in the geoid undulations. This effect will be represented in the undulation standard deviations that have been calculated using the least-squares collocation procedure. the average accuracy is ±16 cm with the range from ±14 to ±48 cm. the dynamic height derived from the gravimetric undulations and altimeter data has been used to calculate characteristics of the Gulf Stream (width, velocity, centre location, height profile) using an implied velocity model for the set. the results are compared with previous estimates with generally good agreement. However, the maximum velocities and the jump function are approximately 30 per cent larger than previous studies that used an average of altimeter tracks to define the geoid undulation. the dynamic topography was calculated for the entire region using a mean sea surface based on Geos-3, Seasat and Geosat data. the results are compared with two hydrographic estimates due to Martel/Wunsch and LeTraon/Mercier. the agreement is at the ±25 cm level with the best correlation coefficient reaching 0.72 with the Martel/Wunsch model.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Surveys in geophysics 14 (1993), S. 373-380 
    ISSN: 1573-0956
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Three geopotential models (OSU91A, GEM-T3, and GRIM4-C2), available in 1991, have been compared in several ways. The models have been differenced to find the geoid undulation difference are on the order of 1 m in land areas and 30 cm in ocean areas with extreme differences reaching 6 m. The models were also evaluated, augmented by higher degree terms, when necessary, through comparisons with undulations at Doppler and GPS positioned stations. The undulation difference at the Doppler stations was ± 1.57 m with no significant difference between models. Using 4 GPS test areas, differences were seen between the various models. A final comparison was made between geoid undulations implied by a Geosat 17 day cycle and undulations from the three models. The OSU91A model performed best having a difference standard deviation of ±34 cm.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Marine geophysical researches 7 (1984), S. 55-67 
    ISSN: 1573-0581
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The Seasat altimeter data has been completely adjusted by a crossing arc technique to reduce the crossover discrepancies to approximately ±30 cm in five regional adjustments. This data was then used to create sea surface heights at 1° intersections in the ocean areas with respect to the GRS80 ellipsoid. These heights excluded the direct tidal effects but included the induced permanent deformation. A geoid corresponding to these sea surface heights was computed, based on the potential coefficients of the GEML2 gravity field up to degree 6, augmented by Rapp's coefficients up to degree 180. The differences between sea surface heights and the geoid were computed to give approximate estimates of sea surface topography. These estimates are dominated by errors in both sea surface heights and geoid undulations. To optimally determine sea surface topography a spherical harmonic analysis of raw estimates was carried out and the series was further truncated at degree 6, giving estimates with minimum wavelengths on the order of 6000 km. The direction of current flow can be computed on a global basis using the spherical harmonic expansion of the sea surface topography. Ths has been done, not only for Seasat/GEML2 estimates, but also using the recent dynamic topography estimates of Levitus. The results of the two solutions are very similar and agree well with the major circulation features of the oceans.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Surveys in geophysics 2 (1975), S. 193-216 
    ISSN: 1573-0956
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The Earth's gravity field can be determined from gravity measurements made on the surface of the Earth, and through the analysis of the motion of Earth satellites. Gravity data can be used to solve the boundary value problem of gravimetric geodesy in various ways, from the classical formulation using a geoid to the concept of a reference surface interior to the masses of the Earth to a statistical method. We now have gravity information for 10 data blocks over 46% of the Earth's surface and more than several million point measurements available. Satellite observations such as range, range-rate, and optical data have been analyzed to determine potential coefficients used to describe the Earth's gravitational potential field. Coefficients, in a spherical harmonic expansion to degree 12, can be determined from satellite data alone, and to at least degree 20 when the satellite data is combined with surface gravity material. Recent solutions for potential coefficients agree well to degree 4, but with increasing disagreement at higher degrees.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Studia geophysica et geodaetica 16 (1972), S. 1-9 
    ISSN: 1573-1626
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Summary A typical geodetic satellite orbit has been computed by numerical integration for a period of thirty hours. The gravitational potential of a standard orbit was represented by the SAO 1969 Standard Earth potential coefficients taken to degree 18. Other orbits were generated using the generalized Stokes' equations and the coating method applied to gravity anomalies and surface densities, in 5°, 10°, 15° and 30° equal-area blocks, derived from the given potential coefficients. The differences between these orbits yield the position differences to be expected when representing the potential field by using gravity data instead of potential coefficients. Using 10°, 15°, and 30° blocks and the generalized Stokes' equations, the position error at the end of thirty hours was 89 meters, 224 meters, and 2060 meters respectively. This error is primarily due to the integration error in computing the gravitational field by summation over a finite number of areas.
    Type of Medium: Electronic Resource
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  • 9
    Publication Date: 2022-05-26
    Description: Under the auspices of the International Association for Physical Sciences of the Ocean (IAPSO) a committee was established to identify the oceanographic and geophysical requirements for fixing Tide Gauge Bench Maries (TGBM's) in an absolute terrestrial coordinate system; to evaluate the technology for fixing TGBM's; and to malce recommendations to the Commission on Mean Sea Level and Tides (IAPSO) of a strategy for coordinated global fixing ofTGBM's and for making the results centrally·available. To meet these goals, the committee met for a several day session at the Woods Hole Oceanographic Institution in November, 1988. From this workshop came a series of technical conclusions, plus specific recommendations to achieve the goals of the committee. Included in these discussions were Very Long Baseline Interferometry, Satellite Laser Ranging, Lunar Laser Ranging, Global Positioning System, and Absolute Gravity Meters, as well as mechanisms for logging and distributing the results from these systems, perhaps via the Permanent Service for Mean Sea Level (PSMSL) in Britain.
    Description: Funding was provided by the International Association for Physical Sciences of the Ocean (IAPSO), the National Oceanic and Atmospheric Administration (NOAA), and the Sea Grant Program through the Woods Hole Oceanographic Institution.
    Keywords: Tide-gages ; Marine geodesy
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
    Format: application/pdf
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