US: NOAA’s National Geodetic Survey (NGS) released the results of three major improvements to the National Spatial Reference System (NSRS). The three improvements to the NSRS are:
-A new realisation of the North American Datum of 1983 (NAD 83);
-New gravimetric and hybrid geoid models; and
-The determination of updated elevations in the Gulf Coast Height Modernisation Project.
These improvements provide users with positions and elevations that are both spatially and temporally consistent.
The first improvement, the NGS update of NAD 83, is referred to as the NAD 83(2011) epoch 2010.00 realisation. This new realization aligns the Continuously Operating Reference Station (CORS) network with the network of passive geodetic control monuments positioned using GNSS technology. The CORS and passive GNSS networks are now optimally aligned at a common epoch date of 2010.00 (January 1, 2010), with the positions referring to a single moment in time. Aligning the two systems best meets user needs by providing consistent and accurate access to the latest realisation of the official national geometric coordinate system.
The NSRS is the consistent coordinate system that defines latitude, longitude, height, scale, gravity, and orientation throughout the United States and its territories. NGS maintains and provides access to the NSRS, which is the foundation for the nation’s transportation, mapping, and charting infrastructure and serves a multitude of scientific and engineering applications.