The National Geodetic Survey (NGS) will replace all three North American Datum of 1983 (NAD 83) frames and all vertical datums, including the North American Vertical Datum of 1988 (NAVD 88), with four new terrestrial reference frames and a geopotential datum. The new reference frames will rely primarily on Global Navigation Satellite Systems (GNSS), such as the Global Positioning System (GPS), as well as on a gravimetric geoid model. NGS has prepared three documents that outline the technical and policy decisions about replacing NAD 83 and NAVD 88: (1) Part 1: Geometric Coordinates publication outlines technical and policy decisions about replacing NAD 83, (2) Part 2: Geopotential Coordinates publication discusses the planned replacement of all vertical datums of the NSRS, and (3) Part 3: Working in the Modernized NSRS publication addresses how geospatial professionals can expect to work within the newly-modernized NSRS when NAD 83 and NAVD 88 are replaced.
This course addresses technical and policy decisions based on the NOAA Technical Report NOS NGS Blueprints for the Modernized NSRS, Part 3. The course will address the following topics: (1) the reasons for modernizing the NSRS, (2) expected coordinate changes between the existing NSRS and the new modernized NSRS, (3) the reason for time-dependent coordinates in the new NSRS, (4) the differences between NGS xGeoid models and hybrid geoids, (5) how North American-Pacific Geopotential Datum of 2022 (NAPGD2022) orthometric heights will be determined using GEOID2022, and (6) models, tools, and products being developed by NGS to help users transition to the new 2022 reference frames.
Objectives
- Learn how the NGS’s new horizontal datum will address NAD 83’s shortcomings by defining four geometric terrestrial reference frames that are based on the tectonic plates with time-dependent components.
- NAPGD2022 GNSS-derived orthometric heights will be determined using GNSS-derived ellipsoid heights and GEOID2022 geoid heights, which will be significantly different from other vertical reference datums, i.e., NGVD 29 and NAVD 88,
- Become aware of the models and tools the NGS is developing to facilitate user transition to the new reference frames.
Good introduction to main concepts of coming changes. Some of the details are challenging for the 'average' non-geodetic surveyor (if there are any of those left) but it is important for all of us to be exposed to this information. I liked that Mr. Zilkoski stressed the importance of keeping up to date with the progress of the new datums and the changing tools on the NGS website.