National Adjustment of 2011 (NA2011)
NAD 83(2011) epoch 2010.00 coordinates on passive control
The National Adjustment of 2011 (NA2011) Project is part of the National Geodetic Survey's (NGS) continuing efforts to improve the National Spatial Reference System (NSRS). The NSRS is the consistent reference system defining latitude, longitude, height, scale, gravity, and orientation throughout the United States and its territories. NGS maintains and provides access to the NSRS, the foundation for the nation's transportation, mapping, and charting infrastructure, as well as a multitude of other scientific and engineering applications.
NA2011 will yield updated North American Datum of 1983 (NAD 83) coordinates on nearly 80,000 NGS passive control marks positioned using Global Navigation Satellite System (GNSS) technology. A primary objective for NA2011 is to ensure that NGS-published coordinates on passive GNSS marks are fully consistent with the Continuously Operating Reference Station (CORS) network. This is necessary because the CORS network is the geometric foundation of the NSRS, and it is important that NGS products and services be mutually aligned to best meet user needs. The NA2011 Project is required now because NGS recently determined a more precise set of coordinates for the CORS, and this realization is referred to as NAD 83(2011) epoch 2010.00. Additional information on the CORS-based realization of NAD 83 is available on the NGS CORS Coordinates web page.
Since NA2011 will yield ellipsoid heights that are inconsistent with the existing geoid model (GEOID09), a new hybrid geoid model, GEOID12, is currently being developed at NGS. GEOID12 will be based on NAD 83(2011) epoch 2010.00 ellipsoid heights, so its release must, therefore, occur after the completion of NA2011.
Our original goal was to complete the NA2011 Project by the end of calendar year 2011. However, completion of the project has been delayed for a number of reasons (such as adding new data, re-enabling previously rejected vectors, additional analysis in subsidence areas, etc.). In addition, NA2011 results will not be made available on NGS Datasheets until GEOID12 has been completed. Assuming no unforeseen delays, the estimated release date for GEOID12, as well as the full implementation of the NAD 83(2011) epoch 2010.00 realization in NGS products and services, is June 30, 2012.
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