New Geometric Datum: plans Modernizing the U.S. National Spatial Reference System FGCS San Diego, California Monday 11 July 2011

Geodetic control is the foundation for all geospatial products. Geodetic Control is the critical “basemap” layer for GIS applications Coordination begins with good coordinates Source: Zurich-American Insurance Group

Crustal velocities Passive networks are aging ( instability, accessibility, loss) How accurate is the NSRS?

stable N.A. world avg. NAD83 vs GNSS 2.2 meters NAD 83 Origin Earth’s Surface ITRF Origin ( Identically shaped ellipsoids )

New geometric datum minus NAD 83 (horizontal)

New geometric datum minus NAD 83 (ellipsoid height)

mm/year

1.6 meter shift on a 1:25,000 map modern users abuse map scale NAD83 and GNSS lat/lon lattices are cm apart Accurate and seamless!! Optimized for my project!!

the path to a new geospatial datum SCIENCE: – participate in international geodesy – maintain core geodetic infrastructure – define stable North America, plate motions, local issues OUTREACH: – illustrate limitations of current system – geospatial summits with FGCS, ACSM, ION, etc. – assist key stakeholders to identify use cases, issues TOOLS: – dependable models – GEOID, NADCON, H(+V) TDP exploitable via vendor toolkits – services for RTN operators

the path to a new geospatial datum DEFINE: – Fixed to plate at what epoch? Update frequency/tolerance? – Coordination with international community, Canada, Mexico, etc. – FGDC vote to adopt, Federal Register Notice, formal report, & FAQ IMPLEMENT: – Products (datasheets, OPUS, GEOIDs, maps, charts, projects) – Toolkit (NADCON, TDP) and best practices – Legacy plan: how much support for USSD, NAD27, NAD83 TIME FRAME: – Follow in synch with geopotential datum effort – Note, NAD27 is still in use.

Benefits, Progress… and Challenges o Benefits o Facilitates direct use of GNSS for positions and “physical” height determination o More closely aligned with CORS and global reference frames (e.g., ITRF) o More efficient, less reliance on passive control o Better monitoring/modeling of temporal change in coordinates, heights, and gravity o Progress o Multi-Year CORS Solution and new adjustment of passive GNSS control o Gravity for the Redefinition of the American Vertical Datum (GRAV-D) project underway o Federal geospatial summits to communicate change to users (2010, 2012, more in future) o Challenges o Coordination with neighbors (Canada and Mexico) o Fix new geometric datum to North American plate? o Integration of GNSS heights (using geoid model) w/geodetic leveling; Dynamic heights o Providing means/best practices for users to move data to new datums o Depends on full funding for GRAV-D (and schedule) o Original completion target 2018, now by 2022…

Geospatial summit 2012 What do you want to talk about? geodesy.noaa.gov/2010Summit/ Presentations Handouts Proceedings

Positioning America for the Future NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION National Ocean Service National Geodetic Survey Replacing NAD 83 Want the new reference system to be more geocentric Option 1: Adopt ITRF20xx Option 2: Adopt reference frame that agrees with ITRF20xx at some instant of time, but does not move relative to “stable” North America.

Positioning America for the Future NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION National Ocean Service National Geodetic Survey Option 1: Adopting ITRF20xx Advantage: Ideally there would be just one reference frame for everyone in the world. (Note: The current WGS84 realization is essentially equivalent to ITRF2000 and its next realization will be essentially equivalent to ITRF2008.) Disadvantage: All points in North America would have significant horizontal velocities –In central & eastern CONUS, between 1 and 2 cm/yr –In California, western Oregon, western Washington, Alaska and Canada, more than 2 cm/yr

Positioning America for the Future NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION National Ocean Service National Geodetic Survey Option 2: Frame fixed to North American plate Advantage: Points in “stable” North America would experience no significant horizontal motion. Disadvantage: Each tectonic plate would need its own reference frame. Hawaii is located on the Pacific plate, Puerto Rico on the Caribbean plate, and Guam on the Mariana plate. Also, points located near plate boundaries would still be moving significantly (eg., California, Oregon, Washington, southern Alaska).

16% of US population lives in the Pacific region.

Positioning America for the Future NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION National Ocean Service National Geodetic Survey Analogy with time systems The world has adopted essentially two time systems: * Universal Coordinated Time (UTC) for global applications * Local time for applications within a single “time zone” The conversion between the two time systems is simply a matter of adding or subtracting an integral number of hours.

Positioning America for the Future NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION National Ocean Service National Geodetic Survey Can the geospatial community deal with two geometric reference systems? ITRF20xx for interplate applications Plate-specific reference frames for intraplate applications A conversion between two given frames would simply involve applying a set of 3 rotation rates.

Positioning America for the Future NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION National Ocean Service National Geodetic Survey EPOCH DATE … date for which published positional coordinates are valid.

National Spatial Reference System (NSRS) The NSRS is a consistent coordinate system that defines latitude, longitude, height, scale, gravity, and orientation throughout the United States. Evolving from passive to active to real-time augmentations  One common datum for all FGDC products (yours too?) Geodetic control: overview & evolution

New Vertical Datum: plans, status, GRAV-D update FGCS San Diego, CA. July 11, 2011 Mark C. Eckl NGS Chief of Observation and Analysis Division, New Vertical Datum Project Manager

NORTH AMERICAL VERTICAL DATUM 1988

NEW VERTICAL DATUM (Topics) Rationale for the New Vertical Datum Components of the Project Plan Estimated Outcome

NEW VERTICAL DATUM (Rationale) To be consistent with the shift in the geometric reference frame/ellipsoid (2022) Improvement in our technical abilities in reference surface realization (geopotential gravimetric reference surface - 1cm accuracy of geoid (GNSS/GRAV-D)) The new geopotential reference surface will be aligned with the geometric reference frame/ellipsoid (i.e., no hybrid geoid) A move away from differentially leveled passive control as the defining mechanism of the reference surface

NEW VERTICAL DATUM (Rationale) The technology to make accurate vertical heights measurements with GNSS technology To provide vertical access to formerly prohibitive places To allow monitoring of physical or geophysical datum deformation

NEW VERTICAL DATUM (Components) Design and adopt new geometric reference frame (Geometric Datum Project) Realize new geometric datum with existing passive/active control, i.e., a horizontal (geometric) adjustment Definition of the W 0 surface as the new datum reference surface Build a gravimetric geoid with an overall accuracy of 1 cm

GRAV-D Processing Update Alabama (‘08) and 2008 Alaska survey already delivered to Geoid team (Newton v1.1) Next major version of aerogravity processing software is complete (Newton 1.2) Newton 1.2 data for Alabama and Louisiana will be delivered to geoid team by early July; other surveys will quickly follow LA/AL airborne gravity data will release publicly in next month via a web page designed to share data Still partnering for flights; seeking a dedicated plane University of New Orleans June 20-21, 2011 Determining Elevations with GNSS Improvements to the Geoid Models 27

GRAV-D Survey Plans FY 2011: – Alaska – California/Oregon coastline – Eastern Great Lakes Region – As of June 1, 13.45% of total area has been surveyed FY2012: – Great Lakes region – Washington State – California FY2013: – Finish Great Lakes – TBD

Alaska FY11West Coast FY11-12 FY11-13 Great Lakes Plan FY10 = Green FY11 = Blue FY12 = Orange FY13 = White (FY11 Already Flown)

NEW VERTICAL DATUM (Components) Studies of: Geoid slope validations Geoid bias Geoid long term monitoring (i.e., change detection) Gravity measurement systems accuracy assessments GNSS ellipsoid absolute height measurements GNSS differential ellipsoid height measurements

Prepare a forward and backward vertical datum conversion strategy - points and maps/charts (ref: NC Pilot Project) NEW VERTICAL DATUM (Components) Work with FGCS for adoption of new/updated (FGCS Vertical Working Group): Standards of Accuracy Specifications Procedures, and Guidelines Outreach

NEW VERTICAL DATUM (Outcome)

NEW VERTICAL DATUM (Goal) Increase the accuracy and utility of the vertical datum by referencing a global geopotential surface, related to global sea-level, which is accessible through space-based measurement systems and which maintains the differential precision associated with any NGS adopted vertical datum.