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Services - Geoid Repository


Regional Models

Alaska (USGG2003/GEOID03)


  Authors: D.R. Roman, Y.M. Wang     Created: 2003    Resp: D.R. Roman  
      Status: PUBLIC    
Description:
USGG2003 is a gravimetric geoid model for Alaska computed by the National Geodetic Survey (NGS). It has a 1'x1' spatial resolution in latitude and longitude. It is the same as the GEOID99 gravimetric model for Alaska, but for the reference frame. In particular USGG2003 is referred to the GRS80 normal ellipsoid in the ITRF00 frame. The geoid determination is based on the use of the one-dimensional spherical Fast Fourier Transform (FFT) to evaluate Stokes' integral. It is performed in the framework of a remove-restore procedure, where long wavelengths come from the EGM96 geopotential model, while the terrain correction is computed by using a digital elevation model with a spatial resolution of 30"x60". The GEOID03 model is also computed for Alaska, but unlike the grid for the conterminous United States, this model does not incorporate GPS/levelling data. It is derived from the USGG2003 gravimetric model for Alaska by changing the reference frame of the GRS80 normal ellipsoid to the NAD83 frame. Due to poorer data coverage, error estimates for USGG2003 and GEOID03 in this region are larger than the ones of USGG2003 in the conterminous United States, especially in the tectonically active areas of southern Alaska.

References:
D.R. Roman, Y.M. Wang, W. Henning, J. Hamilton (2004). Assessment of the New National Geoid Height Model, GEOID03. Surveying and Land Information Science, 64(3), pp. 153-162.

Alaska