New Datums: Replacing NAVD 88 and NAD 83

Transcription

1 New Datums: Replacing NAVD 88 and NAD 83 By Dave Zenk PE, LS National Geodetic Survey Northern Plains Regional Advisor 1735 Lake Drive West Chanhassen, MN office mobile July 25, 2017 South Dakota Statewide Geospatial Conference 1

2 Outline Why replace NAD 83 and NAVD 88? Recap of Customer Concerns Recent Decisions: Naming conventions and white papers Anticipated effects of datum change and how to prepare July 25, 2017 South Dakota Statewide Geospatial Conference 2

3 Why replace NAVD 88 and NAD 83? ACCESS! easier to find the sky than a 60-year-old bench mark GNSS equipment is cheap and fast ACCURACY! easier to trust the sky than a 60-year old bench mark immune to passive mark instability GLOBAL STANDARDS! systematic errors of many meters across the US aligns with GPS, international efforts aligns with Canada, Mexico GEOPHYSICS! Gravity defines level surfaces Satellite orbits based on gravitational center of mass July 25, 2017 South Dakota Statewide Geospatial Conference 3

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5 SD Passive Mark Network July 25, 2017 South Dakota Statewide Geospatial Conference 5

6 NAVD 88 is tilted and biased compared to gravitational potential July 25, 2017 South Dakota Statewide Geospatial Conference 6

7 # monumented passive marks are old 16,000 14,000 12,000 10,000 8,000 6,000 4,000 2,000 - when were geodetic marks set? midwest USA SD ND NE MN IA July 25, 2017 decade South monumented, Dakota Statewide Geospatial per NGS datasheet Conference 7

8 passive marks may lie still, but they still lie small instability x long time = inaccuracy July 25, 2017 South Dakota Statewide Geospatial Conference 8

9 NAVD 88 is not America s only datum NAVD 88 North American Vertical Datum of 1988 PRVD02 Puerto Rico Vertical Datum of 2002 ASVD02 American Samoa Vertical Datum of 2002 NMVD03 Northern Marianas Vertical Datum of 2003, 3 each GUVD04 Guam Vertical Datum of 2004 VIVD09 Virgin Islands Vertical Datum of 2009, 3 each Hawaii Hawaiian Islands Vertical Datum (coming soon) various local datums, as national datum is inaccessible IGLD 85 International Great Lakes Datum of 1985 IGSN71 gravity dataset GEOID12B geoid undulations DEFLEC12B deflection of the vertical July 25, 2017 South Dakota Statewide Geospatial Conference 9

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12 NAD 83 is non-geocentric h 83 h yy Earth s Surface IGS yy Origin same GRS-80 ellipsoid NAD 83 Origin July 25, 2017 South Dakota Statewide Geospatial Conference 12

13 NAD 83(2011) to IGS08 at epoch July 25, 2017 South Dakota Statewide Geospatial Conference

14 July 25, 2017 South Dakota Statewide Geospatial Conference NAD 83(2011) to IGS08 at epoch

15 July 25, 2017 South Dakota Statewide Geospatial Conference NAVD88 to NAPGD

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17 NAD 83 is not plate fixed very well If NAD 83 were truly plate fixed then an 8 year epoch change would not yield the systematic plate rotation seen here. NAD 83(2011) epoch minus NAD 83(NSRS2007) epoch July 25, 2017 South Dakota Statewide Geospatial Conference 17

18 ITRF is now mature worldwide research sites July 25, 2017 South Dakota Statewide Geospatial Conference 18

19 ITRF is now mature smaller changes each epoch July 25, 2017 South Dakota Statewide Geospatial Conference 19

20 NAD 83 is not ITRF GPS & WAAS navigation uses WGS84, aligned to ITRF satellite orbits and other geospatial datasets use global frames our TRFs will agree with ITRF (specifically, IGSyy) at the initial epoch our TRFs will diverge from ITRF by a few cm each year to stay plate-fixed difference is a simple Euler plate rotation many areas will diverge further, as no plate is perfectly rigid plate-fixed or ITRF-fixed; can t have both July 25, 2017 South Dakota Statewide Geospatial Conference 20

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23 NAD 83 versions NAD 83 (1986) NAD 83 (HARNs) NAD 83 (FBNs) NAD 83 (NSRS) NAD 83 (2011) NAD 83 (PA11) NAD 83 (MA11) July 25, 2017 South Dakota Statewide Geospatial Conference 23

24 Everything must shift RED: NAD 83 coastline against NAD 83 imagery GREEN: Coastline shifted into NATRF2022 but the imagery remains on NAD 83 July 25, 2017 South Dakota Statewide Geospatial Conference 24

25 Summary: The NSRS in 2022 Four semi-dynamic reference frames Geoid/GPS based vertical datum All data will be time tagged All coordinates will come from GNSS surveys July 25, 2017 South Dakota Statewide Geospatial Conference 25

26 Recap Previous Geospatial Summits 2010 summit changes proposed 2015 summit changes described 2017 summit changes detailed reports, proceedings, presentations, and videos available on-line 100% 90% 80% 70% 60% 50% 40% 30% 20% Are you aware that NGS will replace NAD83 and NAVD 88 with new geometric and vertical datums? I am very aware I am somewhat aware I am not at all aware 10% 0% Not applicable 1/1/2013 1/1/2014 1/1/2015 1/1/2016 1/1/2017 July 25, 2017 South Dakota Statewide Geospatial Conference 26

27 Customer Concerns control shouldn t move! a national terrestrial reference frame should minimize velocities, even if that means drifting away from ITRF/WGS84 over time. don t make us think! provide vendor- and user-friendly transformation tools with modern programming modernize datasheets and bluebooking tell us more! more updates, training, & tutorials a formal publication describing the differences between NAD 83 / NAVD 88 and the new reference frames help with legislation NSPS distribute sample language to update state legislation that references NAD 83 July 25, 2017 South Dakota Statewide Geospatial Conference 27

28 control shouldn t move! a national terrestrial reference frame should minimize velocities, even if that means drifting away from ITRF/WGS84 over time. don t make us think! provide vendor- and user-friendly transformation tools with modern programming modernize datasheets and bluebooking Customer Concerns tell us more! more updates, training, & tutorials a formal publication describing the differences between NAD 83 / NAVD 88 and the new reference frames help with legislation NSPS distribute sample language to update state legislation that references NAD 83 Subscribe for notifications July 25, 2017 South Dakota Statewide Geospatial Conference 28

29 Some recent decisions: Names and Blueprints Dru Smith NSRS Modernization Manager NOAA s National Geodetic Survey July 25, 2017 South Dakota Statewide Geospatial Conference 29

30 Since 2008 NGS has had two ten year plans Heavy on broad sweeping decisions e.g. Replace NAD 83 Light on details How? What do we call it? 2016 was a good year for filling in those details July 25, 2017 South Dakota Statewide Geospatial Conference 30

31 So what s new? Names July 25, 2017 South Dakota Statewide Geospatial Conference 31

32 Names The Old: NAD 83(2011) NAD 83(PA11) NAD 83(MA11) The New: The North American Terrestrial Reference Frame of 2022 (NATRF2022) The Caribbean Terrestrial Reference Frame of 2022 (CATRF2022) The Pacific Terrestrial Reference Frame of 2022 (PATRF2022) The Mariana Terrestrial Reference Frame of 2022 (MATRF2022) July 25, 2017 South Dakota Statewide Geospatial Conference 32

33 Names Orthometric Heights Normal Orthometric Heights Dynamic Heights Gravity Geoid Undulations Deflections of the Vertical The Old: NAVD 88 PRVD 02 VIVD09 ASVD02 NMVD03 GUVD04 IGLD 85 IGSN71 GEOID12B DEFLEC12B The New: The North American-Pacific Geopotential Datum of 2022 (NAPGD2022) - Will include GEOID2022 July 25, 2017 South Dakota Statewide Geospatial Conference 33

34 So what s new in 6 months? Names Scientific Decisions Codified in Blueprint for 2022 documents July 25, 2017 South Dakota Statewide Geospatial Conference 34

35 Scientific Decisions Blueprint for 2022, Part 1: Geometric Four plate-fixed Terrestrial Reference Frames And what plate fixed means Mathematical equation between IGS and TRFs Plate Rotation Model for each plate Coordinates at survey epoch Intra-frame velocity model To compare coordinates surveyed at different epochs July 25, 2017 South Dakota Statewide Geospatial Conference 35

36 Replacing the NAD 83 s Three plate-(pseudo)fixed frames will be replaced with four plate-fixed reference frames N. Amer., Pacific, Mariana, Caribbean(new!) Remove long-standing non-geocentricity of NAD 83 frames All four : identical to IGSxx at a TBD epoch ? All four : differ from IGSxx by plate rotation only Updated Euler Pole determination for rigid plate only July 25, 2017 South Dakota Statewide Geospatial Conference 36

37 Four Frames/Plates in 2022 NATRF2022 MATRF2022 PATRF2022 CATRF2022 Image from Snay 2003 July 25, 2017 South Dakota Statewide Geospatial Conference 37

38 Each frame will get 3 parameters - Euler Pole Latitude - Euler Pole Longitude - Rotation rate (radians / year) This will be used to compute time-dependent TRF2022 coordinates from time-dependent IGS coordinates. July 25, 2017 South Dakota Statewide Geospatial Conference 38

39 NATRF2022 frame is rigid and fixed to rigid part of the N.A. plate Non-rigid part of the N.A. plate (deformation) July 25, 2017 area South Dakota Statewide Geospatial Conference 39

40 NATRF2022 coordinates over time (Remember: The NATRF2022 frame is rigid) Point on deforming part of plate Point on rigid part of plate l l t t July 25, 2017 South Dakota Statewide Geospatial Conference 40

41 NATRF2022 coordinates over time (Remember: The NATRF2022 frame is rigid) Point on deforming part of plate Point on rigid part of plate l l t t July 25, 2017 South Dakota Statewide Geospatial Conference 41

42 NATRF2022 coordinates over time (Remember: The NATRF2022 frame is rigid) Point on deforming part of plate Point on rigid part of plate l l t t July 25, 2017 South Dakota Statewide Geospatial Conference 42

43 NATRF2022 coordinates over time (Remember: The NATRF2022 frame is rigid) Point on deforming part of plate Point on rigid part of plate l l t t July 25, 2017 South Dakota Statewide Geospatial Conference 43

44 Intra-frame velocities Longitude (Easting) History of DI4044 Residual Trend: -1.7 mm / year This is the velocity of the point in NATRF2022. Rotation of plate removed. It is not constant because the point still suffers small intra-frame velocities. Such IFVs will be captured in a model by NGS Trend: mm / year July 25, 2017 South Dakota Statewide Geospatial Conference ITRF NATRF2022 This is the velocity of the point in ITRF. Includes all movements, but the dominant one is the rotation of the N.A. Plate. 44

45 Scientific Decisions!! Blueprint for 2022, Part 2: Geopotential Global 3-D Geopotential Model (GGM) Will contain all GRAV-D data Able to yield any physical value on/above surface Special high-resolution geoid, DoV and surface gravity products consistent with GGM Not global: NA/Pacific, American Samoa, Guam/CNMI Time-Dependencies Geoid monitoring service Impacts of deglaciation, sea level rise, earthquakes, etc July 25, 2017 South Dakota Statewide Geospatial Conference 45

46 GEOID2022 (et al) over American Samoa: -16 to -10, GEOID2022 (et al) over Guam/CNMI: 11-22, GEOID2022 (et al) over the North America/Pacific/Caribbean/Central America/Greenland region will range from 0 to 90 latitude and from 170 to 350 longitude. July 25, 2017 South Dakota Statewide Geospatial Conference 46

47 Blueprint for 2022 Part 1: Geometric now available April 2017 Part 2: Geopotential coming soon, Summer 2017 Part 3: Bluebooking July 25, 2017 South Dakota Statewide Geospatial Conference 47

48 Time-Dependencies as a service: NATRF2022 and actual survey epochs NAD 83 forcibly combined data spanning many years (using HTDP with no vertical modeling) to compute and find one height at one epoch. NATRF2022 will compute coordinates at survey epoch to show actual motion. Even gridding surrounding CORS yields better subsidence rates than you have today. July 25, 2017 NAD 83 best estimate of dh/dt: +2.8 mm / year NATRF2022 best estimate of dh/dt: -4.2 mm / year CORS best estimate of dh/dt: -2.2 mm / year South Dakota Statewide Geospatial Conference 48

49 Change and Preparedness July 25, 2017 South Dakota Statewide Geospatial Conference 49

50 SHIFTS: 1.25 meters N&W x 0.75 meters VERT Changes in Lat/Lon/EllHT and OrthoHt not negligible Systematic shift over local areas Paper maps at scale of 1 =100 feet, change = 0.04 (1 mm) So, overlays of new data on old data may be a concern. July 25, 2017 South Dakota Statewide Geospatial Conference 50

51 Laws and Rules Many states embody requirements for datums in state law or agency rules. These requirements will need changing in order for transition to new datums. Work with SDSPLS Legislative Committee and others, refer to NSPS Model Legislation State NAD83 NAD27 NAVD88 NGVD29 SPCS27 SPCS83 Iowa x x Minnesota x x x x North Dakota x x x x Nebraska x x South Dakota x x x x 50 State TOTALS July 25, 2017 South Dakota Statewide Geospatial Conference 51

52 Databases and Software Many databases were designed with coordinate conversions in mind, but not all. Some cannot handle datum conversions, even if they handle coordinate conversions. NGS will release NADCON 5 to assist in managing datum and coordinate conversions. Will your software be ready? July 25, 2017 South Dakota Statewide Geospatial Conference 52

53 Client Education Many clients may not understand what datums are. NGS has resources available to help explain the concepts. July 25, 2017 South Dakota Statewide Geospatial Conference 53

54 Correct and Current Metadata There are many current data sets that lack correct and current metadata. Now would be a good time to inventory and update/correct any such records in your possession. A clever practitioner could search the metadata record for Section 4 FGDC section Horizontal Coordinate System Definition July 25, 2017 South Dakota Statewide Geospatial Conference 54

55 Questions Dave Zenk PE, LS National Geodetic Survey Northern Plains Regional Advisor 1735 Lake Drive West Chanhassen, MN home office office mobile (federal business) (personal business) July 25, 2017 South Dakota Statewide Geospatial Conference 55