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Progress toward the Progress toward the Geopotential Reference Geopotential Reference
FrameFrame
Dru SmithDru SmithDan RomanDan Roman
Vicki ChildersVicki Childers45 minutes45 minutes
April 13, 2015 2015 Geospatial Summit 1
Outline• Background• Terminology• What does “done” look like?– Spoiler alert: there are 5 components…
• Getting to “done”– Spoiler alert: we need 12 “things” to exist…
• Progress toward completion• What comes after “done”?
April 13, 2015 2015 Geospatial Summit 2
Background
• What’s being replaced:
Horizontal Vertical– NAD 83(2011)
– NAD 83(PA11)
– NAD 83(MA11)
April 13, 2015 2015 Geospatial Summit 3
– NAVD 88
– PRVD 02
– VIVD09
– ASVD02
– NMVD03
– GUVD04
– IGLD 85
LatitudeLongitudeEllipsoid HeightState Plane Coordinates
Heights
Terminology
• Horizontal Datum– Geometric Reference Frame
• Geocentric X, Y, Z
• Latitude, Longitude, Ellipsoid Height
• Vertical Datum– Geopotential Reference Frame
• Geoid undulation
• Orthometric height
• Gravity
• Deflection of the Vertical
April 13, 2015 2015 Geospatial Summit 4
What does “done” look like?1 of 5
April 13, 2015 2015 Geospatial Summit 5
New Geometric Reference Frame @ survey epoch
= 38° 42’ 13.777418”
= 073° 17’ 46.70141”
h = 146.422 m New Geopotential Reference Frame @ survey epoch
H = 183.222m
H = 186.202mDyn
1: This version ofOPUS exists
What does “done” look like?2 of 5
April 13, 2015 2015 Geospatial Summit 6
= 38° 42’ 13.74020”
= 073° 17’ 46.73029”
h = 147.034 m
NAD 83(2011)* epoch 2010.00
New Geometric Reference Frame epoch 2022.00
2: This new transformation tool exists
= 38° 42’ 13.777418”
= 073° 17’ 46.70141”
h = 146.422 m * Or NAD 83(PA11) or NAD 83(MA11)
What does “done” look like?3 of 5
April 13, 2015 2015 Geospatial Summit 7
NAVD 88, and etc*
New Geopotential Reference Frame, epoch 2022.00
3: This new transformation tool exists
H = 586.444m
* Helmert Orthometric Heights in NAVD 88.
Normal Orthometric Heights in PRVD02, ASVD02, NMVD03, GUVD04, VIVD09 All, “as published in 2022.00”.
H = 587.133m
What does “done” look like?4 of 5
April 13, 2015 2015 Geospatial Summit 8
IGLD 85
New Geopotential Reference Frame, epoch 2022.00
4: This new transformation tool exists
H = 843.162m
Dyn
H = 842.773m
Dyn
What does “done” look like?5 of 5
April 13, 2015 2015 Geospatial Summit 9
5: The FGCS has voted to approve the new frames
“Done” : SummaryA. OPUS: All basic coordinates in new framesB. Tool: Lat/Lon/Eht to new geometricC. Tool: Ortho heights to new geopotentialD. Tool: Dynamic heights to new geopotentialE. FGCS approval
April 13, 2015 2015 Geospatial Summit 10
Getting to “done”
April 13, 2015 2015 Geospatial Summit 11
A.K.A. What must exist to get to “done”?
Getting to “done”1: IGSxx = The most recent IGS reference frame prior to 2022
April 13, 2015 2015 Geospatial Summit 12
Getting to “done”2: A complete, self-consistent airborne-based gravity* data set over the USA and territories, at epoch 2022.0, in IGSxx.
* “gravity” will mean “vertical acceleration of gravity” unless stated otherwise
April 13, 2015 2015 Geospatial Summit 13
g
Getting to “done”3: A terrestrial gravity data set over the USA and territories, consistent with #2, at epoch 2022.0
April 13, 2015 2015 Geospatial Summit 14
Getting to “done”4: A DEM of ellipsoid heights in IGSxx/GRS-80 at 30 meter resolution, for epoch 2022.0, over the USA and territories
April 13, 2015 2015 Geospatial Summit 15
Getting to “done”5: Three final geoid models (North America, Guam/CNMI and American Samoa), consistent with #2, #3 and #4, each centered at the center of IGSxx
April 13, 2015 2015 Geospatial Summit 16
Getting to “done”6: Three geoid secular velocity models, as companions to #5
April 13, 2015 2015 Geospatial Summit 17
cm / yr
Getting to “done”7: GNSS positioning in all OPUS products in IGSxx at the epoch of the survey
April 13, 2015 2015 Geospatial Summit 18
IGSxx @ survey epoch
= 38° 42’ 13.777418”
= 073° 17’ 46.70141”
h = 146.422 m
Getting to “done”8: Software to interpolate geoid undulations
April 13, 2015 2015 Geospatial Summit 19
Getting to “done”9: Software to compute dynamic heights from ellipsoid heights, geoid undulations and surface gravity
April 13, 2015 2015 Geospatial Summit 20
DynhNg
H
Getting to “done”10: GNSS survey on NAD 83 marks
April 13, 2015 2015 Geospatial Summit 21
,,h in NAD 83(2011)*
~”thousands”
* Or NAD 83(PA11) or NAD 83(MA11)
Thankfully the CORS are the first 2000 such points with both “recent GNSS data” and “published NAD 83 coordinates”
Getting to “done”11: GNSS survey on NAVD 88 marks
April 13, 2015 2015 Geospatial Summit 22
H in NAVD 88*
~”thousands”
* Or PRVD02, ASVD02, NMVD03, GUVD04, VIVD09
Getting to “done”12: GNSS survey on IGLD 85 marks
April 13, 2015 2015 Geospatial Summit 23
H in IGLD 85
~”hundreds”
Dyn
Getting to “done”: Summary
1) IGSxx2) Airborne Gravity3) Surface Gravity4) DEM5) 3 Geoid models6) 3 Geoid change
models
April 13, 2015 2015 Geospatial Summit 24
7) OPUS in ITRFxx8) Interp. software9) Dyn. Ht software10)GPS on 83 marks11)GPS on 88 marks12)GPS on 85 marks
Progress toward completion
April 13, 2015 2015 Geospatial Summit 25
Progress toward completion: Warning
• NGS has lost significant expertise in the last few years and has struggled to gain new expertise.
• Many tasks listed next are in RED, indicating they are are likely to cause failure at 2022 if not corrected quickly.
April 13, 2015 2015 Geospatial Summit 26
Progress toward completion:#1) IGSxx
1) The creation of each iteration of IGSxx is done under the auspices of the IGS (part of the IERS)
2) NGS participates in and contributes to this process but does not control it
3) In the absence of any future IGSxx’s, NGS will use IGS08
April 13, 2015 2015 Geospatial Summit 27
Progress toward completion:#2) Airborne Gravity
1) GRAV-D is on track for a 2021 completion42% done as of today
2) Re-processing into new IGSxx’s is time consuming. May require substantial contract work immediately prior to 2022.
3) Decision about how to move old surveys into epoch 2022.0 is being hotly debated in NGS
April 13, 2015 2015 Geospatial Summit 28
g
Progress toward completion:#3) Surface Gravity
1) NGS has over 2 million surface gravity points at epochs spanning a century
2) No comprehensive effort is currently underway to adjust these data to be consistent with airborne gravity.
April 13, 2015 2015 Geospatial Summit 29
Progress toward completion:#4) DEM
1) A DEM exists from SRTM data covering all needed areas at the correct resolution
2) The DEM epoch is 2000
3) Other DEMs (TerraSar-X, etc) may need to be adopted to achieve a DEM nearer to the 2022.0 epoch
4) Transformation of the final DEM will still need to occur to be in IGSxx
April 13, 2015 2015 Geospatial Summit 30
Progress toward completion:#5) Geoid Models
1) Experimental geoid models have been created with airborne gravity since 2011, and regularly since 2014
2) Geoid Slope Validation Surveys have begun (2011) to prove the accuracy of a gravimetric geoid model– 2011: 1 cm proven! – 2014: Being analyzed – 2016: Line Investigation begins next month
3) An agreement with Canada on W0 exists.
April 13, 2015 2015 Geospatial Summit 31
Progress toward completion:#5) Geoid Models
4) NGS does not yet have internal agreement about the proper and final method of combining all gravimetric data sources into a geoid model.
5) The plan to ensure Canada and Mexico are in agreement upon final data sets and final computational methods to arrive at a mutually acceptable North American geoid model in 2022 is not yet complete.
April 13, 2015 2015 Geospatial Summit 32
Progress toward completion:#6) Geoid Velocity Models
1) Satellite missions, especially GRACE, currently provide a secular view of geoid shape change through time
2) NGS has decided that episodic geoid shape changes, such as Earthquakes, will be re-surveyed at a to-be-determined threshold.
3) NGS has decided that periodic geoid change (annual melt/thaw cycles of glaciers) will not be tracked as part of the geoid.
April 13, 2015 2015 Geospatial Summit 33
Progress toward completion:#6) Geoid Velocity Models
4) The geoid’s size (i.e. its relationship to rising sea level) is being hotly debated at NGS.
5) No plan exists at NGS for how we will monitor secular geoid change in the absence of satellite missions.
April 13, 2015 2015 Geospatial Summit 34
Progress toward completion:#7) OPUS in IGSxx
This has been covered in the “Progress toward a new Geometric Reference Frame” talk.
April 13, 2015 2015 Geospatial Summit 35
h
Progress toward completion:#8) Interpolation Software
1) NGS has many products and services that require interpolation from either random points or off of a grid.
2) Many of the historic interpolators presumed computers had little RAM which meant loading less of the grid. This meant ease of use but “step function” errors could occur. Small RAM is less of an issue today and entire geoid grids could easily be loaded in most modern personal computers.
3) NGS must decide which interpolator to install in all products and services
April 13, 2015 2015 Geospatial Summit 36
Progress toward completion:#9) Dynamic Height
Software1) Dynamic heights in IGLD85 came from geopotential numbers which, in turn,
came from surface gravity and field leveling.
2) In the new geopotential reference frame, GNSS based ellipsoid heights, will be converted (via a geoid) into orthometric heights which will then be converted to geopotential numbers using surface gravity which will then, finally, be converted into dynamic heights. No leveling.
3) No resources have yet been allocated to study the accuracies achievable from GNSS-derived dynamic heights, nor to convert that research into a functioning piece of software for customer use.
April 13, 2015 2015 Geospatial Summit 37
DynhNg
H
Progress toward completion:#10) GPS on NAD 83 points
1) To properly support a transformation tool, any new GNSS on NAD 83 points must occur near enough to 2022 that the IGSxx velocities remain linear (no accelerations or earthquakes)
2) NGS supports a “GPS on BM” campaign annually, which often collect data on joint NAD 83/NAVD 88 points.
3) In order to support the greatest nationwide accuracy, a national GNSS campaign should occur between about 2018 and 2021
April 13, 2015 2015 Geospatial Summit 38
Progress toward completion:#11) GPS on NAVD 88
points1) Similar to #10
2) Thankfully, most “GPS on BM” data are on joint NAD 83/NAVD 88 points.
April 13, 2015 2015 Geospatial Summit 39
Progress toward completion:#12) GPS on IGLD85 points
1) Similar to #10 and #11, but research mentioned in #9 must occur
2) A joint USA/Canada campaign to survey GPS on as many IGLD85 points as possible should occur near 2021
April 13, 2015 2015 Geospatial Summit 40
Progress toward completion:Summary
1) NGS is in critical shortage of geodesists to accomplish all of the tasks needed to have the geopotential reference frame complete by 2022
2) Numerous “nice, but not necessary” tasks have been reduced in priority to make success more likely (like having a gravity or DOV interpolator built into OPUS).
April 13, 2015 2015 Geospatial Summit 41
What comes after “done”?
April 13, 2015 2015 Geospatial Summit 42
What comes after “done”?
1) What you’ve seen is the bare minimum for NGS to successfully define, maintain and provide access to a new geopotential reference frame.
2) Other significant tasks remain. With additional resources, they could be accomplished before 2022. Without them, they will not be started until after 2022.
April 13, 2015 2015 Geospatial Summit 43
Thank You!
April 13, 2015 2015 Geospatial Summit 44
http://www.ngs.noaa.gov/datums/newdatums/
1) Coordinates in the new frames will evolve over time, but the transformation tool will only take you to epoch 2022.0.
2) Nothing was said about passive control being published in the new reference frames.
3) OPUS doesn’t yield up other values of interest, like deflections of the vertical, geopotential or acceleration of gravity.
April 13, 2015 2015 Geospatial Summit 45
“Done” : What you probably noticed was missing
“Done” : What you probably noticed was missing
4) Nothing was mentioned about whether latitude and longitude would be plate fixed
5) Nothing was said about NGS accepting GNSS or leveling or gravity or DOV or traverse surveys in the new geopotential reference frame
April 13, 2015 2015 Geospatial Summit 46
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