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Regional Models

Colorado - USA (ColUNBSH2019)

  Authors: K. Matsuo, R. Forsberg   Created: 2019    Resp: K. Matsuo  
                       Status: PUBLIC   Licence: CC BY 4.0
The ColUNBSH2019 gravimetric quasi-geoid and geoid models have been computed by the Geospatial Information Authority of Japan (GSI) in cooperation with the Technical University of Denmark (DTU). 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 109°W ≤ longitude ≤ 103°W, 36°N ≤ latitude ≤ 39°N with a grid spacing of 1' in both latitude and in longitude. Terrestrial and airborne gravity data are combined and gridded by least-squares collocation with the planar logarithmic covariance model. The resulting grid of free-air gravity anomalies is converted into Helmert gravity anomalies by applying the spherical topographic reduction and the analytical downward continuation. The computation method is based on the remove-compute-restore technique, using XGM2016 up to degree and order 719 as the reference global gravity model. In particular, the geoid model is computed by Stokes integration of residual Helmert gravity anomalies with the hybrid Meissl-Molodensky modified spheroidal Stokes kernel (UNB Stokes-Helmert scheme). Finally, the quasi-geoid model is obtained by subtracting the classical geoid/quasi-geoid separation term from the geoid model. The accuracy of the quasi-geoid and geoid models, when compared against GSVS17 GPS/leveling, is equal to 2.0 cm and 1.7 cm, respectively.

K. Matsuo, R. Forsberg (2019). Gravimetric geoid computation over Colorado based on Remove-Compute-Restore Stokes-Helmert scheme. Presented at the 27th International Union of Geodesy and Geophysics (IUGG) General Assembly, 8-18 July 2019, Montreal, Canada.
K. Matsuo, R. Forsberg (2019). Colorado geoid computation - GSI/DTU solution. Report of the Joint Working Group 2.2.2 "The 1 cm geoid experiment", pp.1-4.