History of the Development of Geodetic Datums in the United States Professional Land Surveyors of Oregon Salem January 24, 2014 Dave Doyle NGS, Chief Geodetic Surveyor (Retired) [email protected] 301-704-9578 1807 PRESIDENT THOMAS JEFFERSON SIGNS LEGISLATION ESTABLISHING THE SURVEY OF THE COAST FERDINAND HASSLER (1770-1843) What’s In a Name? 1807 - Survey of the Coast 1836 - Coast Survey 1878 - US Coast and Geodetic Survey 1970 - National Ocean Service National Geodetic Survey JASPER BILBY BILBY TOWER CONSTRUCTION Cutting Edge Surveying Technology circa 1890 Salina, KS Baseline Measurement – 1896 6.5 km/4.1 mi required about 5 weeks Precision ~ 8 mm/0.03 ft (1:721,600) Advances in distance measurement technology Early 1900s Electronic technology 1950s - 1970 A Game Changer 1984 AN END OF AN ERA GLOBAL SATELLITE TRIANGULATION NETWORK (BC-4) 1964-1973 ECHO/PAGEOS BALLOON SATELLITE TYPE PHOTOGRAPHED BY BC-4 BC-4 CAMERA PHOTOGRAPH PAGEOS SATELLITE AGAINST THE STAR BACKGROUND U.S. NAVY NAVSAT TRANSIT SATELLITE “Doppler” Prototype Launched (Failed) 1959 First Successful Test 1960 Operational 1964 (Military) Civilian Access 1967 Transit Geoceiver and VLBI Relative Positional accuracy ~ 0.002 m Relative Positional accuracy ~ 1 m International VBLI Network Global Positioning System GPS Block I GPS Block II GPS Block III . February 22, 1978 - 1st NAVSTAR Satellite launched . July 17, 1995 - System Fully Operational . May 1, 2000 - Selective Availability turned off . September 26, 2005 - L2C band added . May 28, 2010 - First L5 Satellite added . Mid 2014 – First Block III scheduled for launch . 2020? - 10-50 cm real-time accuracy! Macrometer V-1000 GPS Receiver 1982 ~ appox. $250,000 each Where are we now?? Global Navigation Satellite System US - GPS Russia - GLONASS EU - Galileo China – BeiDou Four positioning and navigation systems . NAVSTAR/GPS – US (Currently 31) . GLONASS – Russia (Currently 24) . GALILEO – EU (Currently 4, 30 by 2019) . BEIDOU – China (30+ by 2020?) GEODETIC DATUMS HORIZONTAL 2-D (Latitude and Longitude) U.S. Standard Datum, NAD 27, NAD 83 (1986) Fixed and Stable - Coordinates seldom change GEOMETRIC 3-D (Latitude, Longitude and Ellipsoid Height) Fixed and Stable - Coordinates seldom change NAD 83 (“HARN”), NAD 83 (CORS96), NAD 83 (2007), NAD 83 (2011) 4-D (Latitude, Longitude, Ellipsoid Height, Velocities) Coordinates change with time (e.g. ITRF00, IGS08) VERTICAL 1-D (Orthometric Height) (Leveling constrained to 1 or more long-term tide stations) (e.g. NGVD 29, NAVD 88, PRVD 02) GEOPOTENTIAL 1-D (Orthometric Height) (Realized by GNSS + High Accuracy Gravimetric Geoid Model – e.g. GRAV-D) National Spatial Reference System (NSRS) Consistent National Coordinate System • Latitude • Longitude • Height • Scale • Gravity • Orientation and how these values change with time NSRS COMPONENTS • National Shoreline - Consistent, accurate, and up-to-date • Networks of geodetic control points - Permanently marked passive survey monuments • National CORS Network - A network of GPS Continuously Operating Reference Stations • Tools -Models of geophysical effects on spatial measurements -e.g., NADCON, INVERSE, SPCS83, UTMS, FORWARD U.S.HORIZONTAL DATUMS NORTH AMERICAN DATUM 1983 (1986 – PRESENT) NORTH AMERICAN DATUM 1927 (1927 – 1986) NORTH AMERICAN DATUM (1913 – 1927) U.S. STANDARD DATUM (1901 – 1913) NEW ENGLAND DATUM (1879 – 1900) ALASKA DATUMS (17 Different 1890 - 1954) BESSEL ELLIPSOID (1848 – 1879) PUERTO RICO DATUM (1901 – 1986) OLD HAWAIIAN DATUM (1928 – 1986) AMERICAN SAMOA DATUM 1962 (1962 – 1993) GUAM DATUM 1963 (1963 – 1993) U.S.VERTICAL DATUMS NORTH AMERICAN VERTICAL DATUM 1988 (1991 – PRESENT) NATIONAL GEODETIC VERTICAL DATUM 1929 (1973-1991) SEA LEVEL DATUM 1929 (1929 – 1973) FOURTH GENERAL ADJUSTMENT (1912) THIRD GENERAL ADJUSTMENT (1907) SECOND GENERAL ADJUSTMENT (1903) FIRST GENERAL ADJUSTMENT (1899) (a.k.a. Sandy Hook Datum) AMERICAN SAMOA VERTICAL DATUM 2002 PUERTO RICO VERTICAL DATUM 2002 NORTHERN MARIANAS VERTICAL DATUM 2003 GUAM VERTICAL DATUM 2004 VIRGIN ISLAND VERTICAL DATUM 2009 HORIZONTAL POSITIONAL CHANGES IN OREGON ASTOR POINT 1851 (SC2012) 46-11-27.99214 123-50-25.73269 NAD 83 (2011) (0.063 m / 0.21 ft) – GEOCON11 46-11-27.99066 123-50-25.73474 NAD 83 (2007) (0.098 m / 0.32 ft) - GEOCON 27.98848 25.73805 NAD 83 (1991) (0.511 m / 1.68 ft) 28.00036 25.72144 NAD 83 (1986) (98.669 m / 323.72 ft) 28.62426 21.20853 NAD 27 (46.863 m / 153.75 ft) 29.759 22.660 USSD/NAD (1093.889 m / 3588.87 ft) 27.62 49-31.74 BESSEL National Spatial Reference System North American Datum of 1983 (NAD 83) – Released 1986 National Geodetic Vertical Datum of 1988 (NAVD 88) – Released 1991 NAD 83 - First civilian datum designed to be consistent with space-based observations (GPS) NAD 83 - First civilian datum to be best-fitting globally not locally NAD 83 - First geodetic datum to be fully automated First geodetic reference system to be available free from WWW Only reference system to freely integrate data from outside sources EARLY NAD 83 NETWORK PROBLEMS NOT “GPSABLE” POOR STATION ACCESSIBILITY IRREGULARLY SPACED POSITIONAL ACCURACY HIGH PRECISION GPS NETWORK (HPGN) HIGH ACCURACY REFERENCE NETWORK (HARN) 1989 - 1997 “GPSABLE” Clear Horizons for Satellite Signal Acquisition EASY ACCESSIBILITY Few Special Vehicle or Property Entrance Requirements REGULARLY SPACED Always within 20-100 Km HIGH ACCURACY A-Order (5 mm + 1:10,000,000) (3 5.5 hr sessions) B-Order (8mm + 1:1,000,000) (2 5.5 hr sessions) OREGON OBSERVED 1991 AVERAGE NAD 83 (1986) POSITIONAL CHANGE 0.25 – 0.65 m / 0.8 – 2.1 Ft ALL NAD 83 (1986) TRIANGULATION READJUSTED TO FIT NEW COORDINATES FEDERAL & COOPERATIVE BASE NETWORKS (FBN/CBN) 1997 -2004 MORE STATE PARTNERSHIPS REMOVE DISTORTIONS IN EARLY HARNS (3-10 CM) ENSURE CONNETIONS TO CORS IMPROVE ELLIPSOID HEIGHT ACCURACY (Not more than 2 cm) AVERAGE NAD 83 (HARN) POSITIONAL CHANGE 0.01 – 0.07 m / 0.03 – 0.2 Ft OREGON OBSERVED 1998 NAD 83 (HARN) TRIANGULATION NOT READJUSTED TO FIT NEW COORDINATES HISTORY OF VERTICAL DATUM IN THE U.S. Pre-National Geodetic Vertical Datum of 1929 (NGVD 29) The first geodetic leveling project in the United States was performed by the Coast Survey from 1856 to 1857 in the vicinity of New York City. General Adjustments of leveling data yielded datums in 1899, 1903, 1907, and 1912. (Sometimes referenced as the Sandy Hook Datum) 1st General Adjustment, Report of the Superintendent of the Coast and Geodetic Survey, 1900, Appendix 8, pgs 347 – 886 2nd General Adjustment, Report of the Superintendent of the Coast and Geodetic Survey, 1903, Appendix 3, pgs 189 – 809 3rd General Adjustment, USC&GS publication “Precise Leveling In the United States 1903- 1907” 4th General Adjustment, USC&GS Special Publication 18 NGS does not offer a utility which transforms from these older datums into newer ones (though some users still work in them!) NATIONAL WATER LEVEL OBSERVATION NETWORK HTTP://WWW.TIDESANDCURRENTS.NOAA.GOV/ Earliest USC&GS Tide Station in Oregon – 1905 at Ft. Stevens Stations Provide Water Level Wind Speed/Direction Barometric Pressure Air/Water Temp. Conductivity/Temp Tsunami/Storm Surge Data Transmission Many but not all are tied to NAVD 88 1st General Adjustment – 1899 http://docs.lib.noaa.gov/rescue/cgs/003_pdf/CSC-0102.PDF 2nd General Adjustment – 1903 http://docs.lib.noaa.gov/rescue/cgs/004_pdf/CSC-0107.PDF 3rd General Adjustment – 1907 http://docs.lib.noaa.gov/rescue/cgs_suppl/QB296U88H391903-1907.pdf 4th General Adjustment – 1912 http://docs.lib.noaa.gov/rescue/cgs_specpubs/QB275U35no181914.pdf HISTORY OF VERTICAL DATUM IN THE U.S. National Geodetic Vertical Datum 1929 (NGVD 29) Original name: “Sea Level Datum of 1929” “Zero height” held fixed at 26 tide gauges Not all on the same tidal datum epoch (~ 19 yrs) Did not account for Local Mean Sea Level variations from the geoid Thus, not truly a “geoid based” datum The National Geodetic Vertical Datum of 1929 is referenced to 26 tide gauges in the US and Canada HISTORY OF VERTICAL DATUM IN THE U.S. NORTH AMERICAN VERTICAL DATUM OF 1988 Use of one fixed height removed local sea level variation problem of NGVD 29 Use of one fixed height did open the possibility of unconstrained cross-continent error build up The H=0 surface of NAVD 88 was supposed to be parallel to the geoid…(close again) The North American Vertical Datum of 1988 is referenced to a single tide gauge in Canada HEIGHT DIFFERENCES IN OREGON N 1904 (QB0688) 2151.19 Ft NAVD 88 (- 0.56 ft) 2147.99 Ft NGVD 29/SLD 29 (- 0.59 ft) 2148.58 FOURTH GENERAL ADJUSTMENT OF 1912 (+ 1.02 ft) 2147.56 THIRD GENERAL ADJUSTMENT OF 1906 (- 0.20 ft) 2147.76 SECOND GENERAL ADJUSTMENT OF 1903 Problems with NAD 83 and NAVD 88 NAD 83 is not as geocentric as it could be (approx. 1.5 m for CONUS). Surveyors don’t see this – Yet NAD 83 is not well defined with positional velocities NAVD 88 is realized by passive control (bench marks) most of which have Not been releveled in 30-40 years NAVD 88 does not easily account for local vertical velocities (subsidence / uplift) Post glacial isostatic readjustment Subsurface fluid/hydrocarbon extraction Sediment loading - Compaction Sea level rise – Astoria = – 0.3 mm/yr (0.1 ft/100 yr) Charleston = + 1.3 mm/yr (0.4 ft/100 yr) NAVD 88 Leveled heights do not truly represent changes in gravity potential When was the passive mark last leveled? Why isn’t NAVD 88 good enough anymore? ELLIPSOID – GEOID RELATIONSHIP H = Orthometric Height - NAVD 88 h = Ellipsoid Height - NAD 83 (2011) N = Geoid Height - GEOID12A H = h – N H h N Geoid Geoid Model Ellipsoid GRS80 Types and Uses of Geoid Height Models Gravimetric (or Gravity) Geoid Height Models (e.g. USGG2012, USGG2009) Defined by gravity data crossing the geoid Refined by terrain models (DEM’s) Scientific and engineering applications Composite (or Hybrid) Geoid Height Models (e.g.