The Ongoing Evolution of NAD83 and NAVD88
The mission of NOAA’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, elevation, and related models and tools, which provides a consistent spatial reference foundation for the nation. Familiar to geospatial professionals, the North American Datum of 1983 (NAD83) and the North American Vertical Datum of 1988 (NAVD88) are the primary user components of NSRS. This presentation will describe the current status of NSRS and will include information about geodetic control data and tools, the national network of GNSS Continuously Operating Reference Stations (CORS), and the popular Online Positioning User Service (OPUS) utility. NGS’ ongoing effort to modernize NSRS, culminating in 2022 with the replacement of NAD83 and NAVD88, will be reviewed, the current status described, and suggestions proposed for user preparation. Included in the discussion will be information about the nationwide Gravity for the Redefinition of the American Vertical Datum (GRAV-D) program and related Geoid Slope Validation Surveys (GSVS), which together are helping formulate a next-generation geoid model, thereby evolving a new paradigm in nationwide elevation determination capability.