National Adjustment of 2011

In case you are not aware the U.S. NGS – National Geodetic Survey has announced an updated North American Datum of 1983 (NAD 83), which is being referred to as NAD 83(2011) epoch 2010.00 – to be precise, or is that accurate?

This adjustment will affect some 80,000 NGS passive  control marks positioned using GNSS. The median adjustment is about 2 cm horizontal and vertical at the 95% confidence level. Since the new realization yielded ellipsoid heights that are inconsistent with the existing geoid model, a new hybrid geoid model, GEOID 12 was developed.

If you are searching for centimeters over long distances you need to care. For more information you can visit the NGS website.

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2 Responses to National Adjustment of 2011

  1. GEOID12 is currently being developed to provide ortho heights (elevations) along with NAD83(2011) since the elipsoid heights are not consistent with NAD83(CORS). Also be aware that the CORS stations are not on NAD83(2011) – only passive stations (monuments).

  2. Oops – the July announcement says that NAD83(2011) now includes CORS!

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