National Geodetic Survey

New Datums coming in 2022

IMAGIN Annual Conference

June 18, 2018

Who am I?

National Geodetic Survey’s

Great Lakes Region Geodetic Advisor

John Ellingson

john.Ellingson@noaa.gov

Cell: 202-306-6904

Thank you for enabling me to come here

and spread the word about the coming new

datums.

Today’s Message…..

Two different datums are being modernized

1. “GEOPOTENTIAL” Datum (Vertical)

2. GEOMETRIC Datum (~Horizontal)

Let’s start with the

GEOPOTENTIAL DATUMreplacing the

North American Vertical Datum of 1988

(NAVD 88)

Goal: to enable use of new technology

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NAVD 88 suffers from bench marks that:

– Are often 80+ years old

– Are almost never re-checked for movement

– Disappear by the thousands every year

– Are seldom being replaced

– May not exist near locations where they are

needed

– Were all determined by leveling from a

single point, allowing unwanted cross-

country error build up

Replacing NAVD 88….Why isn’t NAVD 88

good enough anymore?

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Newer methods to determine/establish heights are

available (GNSS), but in many places NAVD 88 doesn’t

support them very well

Why isn’t NAVD 88 good

enough anymore?

There are areas where

NAVD 88 marks are

scarce….or do not exist

This example is 100 miles

across

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Initial point of NAVD 88 …. “FATHER POINT”

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Why replace NAVD 88?

• BIAS of Approximately ½ meter

• KNOWN TILT ..(about a meter) from SE to NW

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GRACE – (NASA and Germany)

“Gravity Recovery and Climate Experiment”

(launched 2002, decommissioned October 2017)

GOCE – (European Space Agency)

“Gravity Field and Steady-State Ocean Circulation

Explorer”

(launched 2009, ended November 2013)

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Gravity for the Redefinition of the American

Vertical Datum

• GRAV-D Goal: Create gravimetric geoid accurate to 1 cm where possible using airborne gravity data

• Overall Target: 2 cm accuracy orthometric heights from GNSS and a geoid model

• GRAV-D: Two thrusts of the project– Airborne gravity survey of entire

country and its holdings

– Long-term monitoring of geoid change

“TRANSITION TO THE FUTURE”

Official NGS policy as of Nov 14, 200710

Survey and Block Plans

• Data lines spaced 10 km

apart

• Cross lines spaced 60-

80 km apart

• Flight altitude 20,000 ft.

• Nominal speed 220-250

knots

GRAV-D current status

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GRAV-D status in Michigan

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NGS Gravity Slope Surveys

to verify that GRAV-D Works

GSVS 2011

GSVS 2014

GSVS 2017

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GRAV-D will produce the new 2022

GEOPOTENTIAL DATUM

known as “NAPGD2022”

……………

NGS will create a new GEOID Model in 2022

to match (use with) NAPGD2022

Older Geoid Models will NOT work with

NAPGD2022

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-

What changes can we expect to see

in our orthometric heights?

Some approx.

delta heights in

MICHIGAN (ft.)

These are

“leveled” height

differences

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-1.9’

-1.7’

-1.8’

-1.9’

-2.2’

-2.0’

-1.8’

-2.0’

-2.2’

-1.9’

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Let’s move on to the new

GEOMETRIC (3D) Datum…

*Latitude

*Longitude

*Ellipsoid Height

The North American Terrestrial

Reference Frame of 2022

“NATRF2022”

NAD 83 was aligned to “Geodetic Reference System

1980” (GRS80), and so was the original “World

Geodetic System 1984 (WGS84) meaning……

NAD 83 IS equivalent to the original WGS 84 …….but

NOT to the newer versions.

Newer versions of WGS 84 have been updated to be consistent with

updated International Terrestrial Reference Frames (ITRF**)

• G730 (June 1994) 0.7 m

• G873 (January 1997) 0.2 m

• G1150 (January 2002) 0.06 m

• G1674 (February 2012) 0.01 m

• G1762 (October 2013) 0.01 m

Why replace NAD 83?

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What is the difference between

ITRF 2008 and NAD 83?

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ITRF 08

Why a new

GEOMETRIC

DATUM?

The big picture

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How will these new datums impact my

work?

• Users in this region will see a GEOMETRIC (3-D) shift

of about 5.3’ (~4’ Lat/Lon & ~ 3.6’ El. HT)

• Some users may take years to switch to the new

datums…!

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The NGS 10 year plan states that a transformation tool will be

provided at the release of the new datums that will enable

users to transform values between the older datums (NAD 83

and NAVD 88) and the new GEOMETRIC and

GEOPOTENTIAL datums.

NGS will provide the tools that you

need to work with the new datums:

Wrap-up of

“New Datums”

• New GEOPOTENTIAL DATUM (vertical) named

“NAPGD2022”

(North American-Pacific Geopotential Datum of 2022)

• New GEOMETRIC DATUM (hz… really 3D)

named “NATRF2022”

(North American Terrestrial Reference Frame of 2022)

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Odds and Ends – (If time permits)

• NGS Industry Days took place in May 2018

• Update on State Plane Coordinate Systems for

New Datums

• IGLD..International Great Lakes Datum- Updated

in 2025

• OPUS-SHARE: Wait Times before you submit

your data to OPUS“Ultra-rapid” (iguWWWWD.sp3) 6-hour latency

“Rapid” (igrWWWWD.sp3) 13-hour latency

“Final or Precise” (igsWWWWD.sp3) 12 to 14 day latency

Questions….

My contact information:

John Ellingson

NGS Great Lakes Region Geodetic Advisor

Cell: 202-306-6904

Email: john.ellingson@noaa.gov

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