NOTICE: NGS Update, September 11, 2012
GEOID12A Model Released
The National Geodetic Survey has released the GEOID12A model. Analysis of the underlying control data has been completed and a number of corrections were made to the original data used in making GEOID12. Changes impacted regions in the states of Alabama, Mississippi, Louisiana, Texas, Oklahoma, and Wisconsin. GEOID12A is now available for production and use.
GEOID12 is a refined hybrid model of the geoid in the United States and other territories, which supersedes the previous models GEOID09, GEOID06, GEOID03, GEOID99, GEOID96, GEOID93, and GEOID90.
This model is intended for converting between the NAD83 ellipsoid reference frame resulting from the National Adjustment of 2011 and vertical datums NAVD88, GUVD04, ASVD02, NMVD03, PRVD02 and VIVD09. See the FAQ page for datum details.
For GEOID12 in CONUS regions, heights range from a low of -50.71 meters (magenta) in the Atlantic Ocean to a high of 3.31 meters (red) in the Labrador Strait. However, these geoid heights are only reliable within CONUS due to the limited extents of the data used to compute it. See link to GPS On Bench Marks Used To Make GEOID12 to the right.
