Future National Reference Frames for the United States

Abstract:

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, elevation, and related geophysical and geodetic models and tools, which provides a consistent spatial reference framework for the broad spectrum of geoscientific applications and other positioning-related requirements. Technological developments – notably Global Navigation Satellite Systems (GNSS) – and user accuracy requirements necessitate that NGS endeavor to 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 presentation will outline the motivation for this effort and the history, current status and planned evolution of NSRS. Fundamental to the delivery of the future reference frame paradigm are new geometric and geopotential (elevation) frameworks. The new geometric reference frame, realized through GNSS Continuously Operating Reference Stations (CORS), will replace the North American Datum of 1983 (NAD83) and will provide the nationwide framework for determination of latitude, longitude, and ellipsoid height. Designed to complement the new geometric reference frame, a corresponding geopotential reference frame – based on a national gravimetric geoid and replacing the North American Vertical Datum of 1988 (NAVD88) – will be developed and co-released. The gravimetric geoid – or definitional reference surface (zero elevation) - for the future geopotential reference frame will be built in part from airborne gravimetric data collected in the ongoing NGS project - Gravity for the Redefinition of the American Vertical Datum (GRAV-D). Suggestions will be presented for steps to be taken in preparation for the transition to the new reference frames.