New Datums for the Nation: Modernizing the United States National Spatial Reference System

The mission of the National Oceanic and Atmospheric Administration's National Geodetic Survey (NGS) is "to define, maintain and provide access to the National Spatial Reference System (NSRS) to meet our nation's economic, social, and environmental needs." NSRS is the nation's system of latitude, longitude, height (geometric and orthometric), and related geophysical and geodetic models and tools, which provides a consistent spatial reference framework for the broad spectrum of geoscientific applications and the majority of civilian positioning requirements. Technological developments - notably Global Navigation Satellite Systems (GNSS) - and user accuracy requirements necessitate that NGS modernize the NSRS. Preparations are underway by NGS for a comprehensive NSRS makeover, to be completed in 2022 and delivered through a new generation of horizontal and vertical datums (reference frames), featuring unprecedented accuracy, repeatability, and efficiency of access. This evolution is outlined in the "National Geodetic Survey Ten-Year Strategic Plan, 2013-2023." This poster will outline the motivations for this effort and the planned evolution of NSRS. New geometric and geopotential (elevation) frameworks are fundamental to the delivery of the future datum paradigms. The new geometric reference frame, realized through GPS/GNSS Continuously Operating Reference Stations (CORS), will replace the backbone North American Datum of 1983 (NAD83) and will provide a modern spatial latticework for determination of latitude, longitude, and ellipsoid height. Complementing the new geometric reference frame will be a co-released geopotential reference frame, based on a national gravimetric geoid and replacing the North American Vertical Datum of 1988 (NAVD88). The gravimetric geoid - or definitional reference surface (zero elevation) - for the future geopotential reference frame will be built from airborne gravimetric data collected in the ongoing NGS project - Gravity for the Redefinition of the American Vertical Datum (GRAV-D).