In 2022, the National Spatial Reference System (NSRS) is scheduled to be modernized, with new reference frames replacing North American Datum (NAD) 83(2011), NAD 83(PA11) and NAD 83(MA11), or the NAD 83 system all together. The North American Vertical Datum (NAVD) 88, which provides the vertical datum used in the United States, will also be replaced. One of the new frames is North American Terrestrial Reference Frame of 2022 (NATRF2022). The other three are: Pacific Terrestrial Reference Frame of 2022 (PTRF2022), Caribbean Terrestrial Reference Frame of 2022 (CTRF2022), and Mariana Terrestrial Reference Frame of 2022 (MTRF2022).[1]
The main reason for this change is the realization that NAD 83 is not as geocentric as it otherwise should be. There is an error of almost up to 2 meters horizontally from the true center point, at least in places, and this has to do with plate tectonics, where slow movement of the Earth’s plates has meant that there is slight error that has been growing in NAD 83 over time. This is also means there needs to be a new datum system not only for North America but also other regions, which is why the NSRS is creating four new systems. Typically, correction would mean resetting a datum point that then has to be re-corrected after some period of time as error builds. Now, NSRS has decided to do things differently, given changes to technologies and the wide presence of satellites.
As outlined by several recent talks by people familiar with the change, the heart of the change is the datum will now be time as well as spatially sensitive. A modern datum is no longer one fixed point but a network of points helps fix the true positioning of the reference point.[2] Satellite navigation using fixed points for coordinates displayed to us are by their design geocentric, since they can theoretically orbit a given center from the planet. The new coordinate reference system will utilize mathematical modeling and satellite data to update the true location of the NATRF2022 datum point, allowing for up to date referencing rather than a fixed position that will over time need to be reset. A geoid model, showing the true curvature and shape of the planet, will be continuously updated as plates and landforms shift. The geoid and input data from satellites will make the datum an essentially “real-time” referencing feature.
This will, inevitably, mean that current maps and user data utilizing the current referencing systems will, once changed to the new system, could have deviations ranging between 0-2 meters at the horizontal level, depending where the location is. Most of the error will likely be found in the Pacific Northwest. The changes to NAVD will mean that there will also be vertical changes or error relative to the current datum. This is projected to be less than the horizontal error, where error corrections should be no greater than 1 meter for the most affected regions that have to update to the new NATRF2022 system. As new data will now be time-sensitive, this will also allow map users to be able to adjust maps to time-specific referencing, whether forward or backward in time relative to a current condition.
To facilitate systems that cannot easily covert to the new NATRF systems, the National Oceanic and Atmospheric Administration (NOAA) will provide a conversion tool to correct for the errors in changing to the new system, which will be found on their website (geodesy.noaa.gov).
References
[1] For more on these specific changes and new reference systems, see: http://ohiosurveyor.org/wp-content/uploads/2017/05/NOAA_TR_NOS_NGS_0062.pdf.
[2] For more on geodetic datum setup and issues, see: Grafarend, E.W. (2010) Map projections: cartographic information systems. Place of publication not identified, Springer, pg. 521.
