The National Spatial Reference System (NSRS) is a key component of our Nation’s infrastructure, supplying defined latitude, longitude, height, and other authoritative geospatial values throughout the United States. While not obvious to the average person, the NSRS is the foundation to nearly every aspect of our lives in which location matters. It underpins aviation, agriculture, emergency response, floodplain mapping, conservation, construction, water management, transportation, and much more. Use of the NSRS ensures consistent coordinates across all geospatial applications in the country.

The North American Datum of 1983 (NAD 83) and North American Vertical Datum of 1988 (NAVD 88), although still the official horizontal and vertical datums of the NSRS, have been identified as having shortcomings that are best addressed through defining new horizontal and vertical datums. Specifically,

• NAD 83 is misaligned to the earth’s center by about 2.2 meters, and

• NAVD 88 is both biased (by about one-half meter) and tilted (about 1 meter coast to coast) relative to the best global geoid models available today.

Correcting these two issues will mean that every existing latitude, longitude, ellipsoid height, and orthometric height in the United States (as reported in the current NSRS) will change by as much as four meters (as reported in the modernized NSRS). Adopting the modernized NSRS is critical, as it finally aligns the NSRS with both international standards, as well as aligning with all Global Navigation Satellite Systems (GNSS), which naturally orbit about, and provide positions relative to, the center of the Earth.

About Gary W. Thompson, PLS

Mr. Gary W. Thompson is the Deputy Hazard Mitigation Chief and Chief of the North Carolina (NC) Geodetic Survey at NC Emergency Management.  He has served as president of both the NC Society of Surveyors (NCSS) and the National Society of Professional Surveyors (NSPS).  He is an emeritus member of the NC Board of Examiners for Engineers and Surveyors (NCBEES) and a commission member of the ABET Applied and Natural Science Accreditation Commission.

This webinar will provide 1 PDH.