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Regional Models

Puerto Rico
and Virgin Islands (USGG2012/GEOID12B)


  Authors: D.R. Roman, Y.M. Wang     Created: 2012    Resp: D.R. Roman  
      Status: PUBLIC    

Description:
The Puerto Rico and the Virgin Islands gravimetric geoid extends from 15N to 21N and from 69W to 64W with a spatial resolution of 1'x1'. It is a pure gravimetric geoid included into the USGG2012 (U.S. Gravimetric Geoid) model. The geoid heights are referred to the GRS80 ellipsoid in the IGS08 (epoch 2005.0) reference frame. The reference global Earth gravity model is EGM2008, with the incorporation of GOCE and GRACE information from the GOCO02S model. Since EGM2008 accounts for the effects of the terrain through about 5' (10 km), SRTM 3" (90 m) data were used to produce a Residual Terrain Model between 3" and 5', accounting for much of the high frequency variability seen in the residual gravity signal. The remove-restore technique employed for the geoid determination is basically the same of the one used for the previous release (USGG2009), see Wang et al. (2012), J Geod 86: 165-180. Additional information is available at: http://www.ngs.noaa.gov/GEOID/. The one line header contains the following parameters: - Southernmost North latitude - Westernmost East longitude - Distance interval in latitude - Distance interval in longitude - Number of rows - Number of columns - Always equal to one While the Hybrid Puerto Rico and the Virgin Islands geoid extends from 15N to 21N and from 69W to 64W with a spatial resolution of 1'x1'. It is a hybrid geoid included into the GEOID12A model, obtained by fitting the corresponding USGG2012 model to GPS-leveling data. The geoid heights are referred to the GRS80 ellipsoid in the NAD 83 (epoch 2010.0) reference frame), which is the official geometric datum of the U.S. National Spatial Reference System. The reference global Earth gravity model is EGM2008, with the incorporation of GOCE and GRACE information from the GOCO02S model. SRTM data were used to produce a Residual Terrain Model between 3" and 5', accounting for much of the high frequency variability seen in the residual gravity signal. After detecting some defects in the GPS/levelling used to create GEOID12, GEOID12A was developed as a replacement. In particular changes impacted regions in the states of Alabama, Mississippi, Louisiana, Texas, Oklahoma, and Wisconsin. There were also some changes in Canada. However, GEOID12A, as with all previous hybrid geoid models (GEOID09, GEOID03), should not be used in Canada or Mexico or in ocean areas more than 30 km offshore. The regions outside of the Conterminous United States were unaffected by these changes, but the name of the model for those regions was changed to GEOID12A for consistency. GEOID12B is a further replacement of GEOID12A with changes only for the Puerto Rico/U.S. Virgin Islands region based on a corrected set of GPS/levelling data. In all areas other than the Puerto Rico/U.S. Virgin Islands region, GEOID12B is identical to GEOID12A. Additional information is available at: http://www.ngs.noaa.gov/GEOID/.  

References:
D.A. Smith, D.G. Milbert (1999). The GEOID96 high resolution geoid height model for the United States. Journal of Geodesy, 73(5), pp. 219-236.
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.
Y.M. Wang, J. Saleh, X. Li, D.R. Roman (2012). The U.S. Gravimetric Geoid of 2009 (USGG2009): Model Development and Evaluation. Journal of Geodesy, 86(3), pp. 165-180. .

Puerto Rico and the Virgin Islands