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Regional Models

Iran (IRG2016)

  Authors: S. Abdoreza Saadat, et al.     Created: 2016    Resp: S. Abdoreza Saadat  
      Status: ON-DEMAND    
IRG2016 is a geoid model for Iran, computed by the National Cartographic Center (NCC) and based on a PhD thesis at University of Tehran. It is bounded between 25°E and 40°E in latitude and between 44°N and 63.5°N in longitude. It is modelled by radial basis functions (RBFs), requiring the determination of their type and number, their horizontal positions, depths, and unknown coefficients. The input observations were 21525 newly-refined gravity data supplied by the NCC of Iran. Residual surface gravity disturbances were computed by subtracting the EIGEN-6C4 model up to degree and order 360 and were used to determine the unknown RBF parameters by the stabilized orthogonal matching pursuit (SOMP) algorithm. The RBF parameters were used to calculate the residual height anomalies. Thus, the residual geoidal height was determined by applying the residual geoid-to-quasigeoid correction. Finally the effect of the long-wavelength part from EIGEN-6C4 was restored. The IRG2016 model was fitted to 1288 GNSS/levelling control points over Iran by applying the polynomial corrector surface. The resulting height reference surface shows an RMS value of approximately 23 cm for the difference in geoidal height at the independent control points.
The 2.5' x 2.5' gridded IRG2016 model (gravimetric and hybrid versions) is on-demand available at the ISG website, while the model interpolation (point-wise or providing an input file) can be performed by an online calculator, according to the NCC policy rules.

S.A. Saadat (2016). Regional gravity field modeling combining terrestrial and satellite gradiometry data based on radial basis functions. PhD thesis in Geodesy at University of Tehran, Iran.
A. Saadat, A. Safari, D. Needell (2018). IRG2016: RBF-based regional geoid model of Iran. Studia Geophysica et Geodaetica, 62(3), pp. 380-407.

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