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GEODETIC DATUMS OF THE U.S. VIRIGN ISLANDS David Doyle Chief Geodetic Surveyor National Geodetic Survey 301-713-3178, dave.doyle@noaa.gov 2nd Annual GIS Conference St. Croix, VI June 22, 2006 National Spatial Reference System National Spatial Reference System (NSRS) (NSRS) Consistent National Coordinate System Consistent National Coordinate System
Latitude Latitude
Longitude Longitude
Height Height
Scale Scale
Gravity Gravity
Orientation Orientation and how these values change with time. and how these values change with time. • National Shoreline - Consistent, accurate, and up-to-date • National CORS - A network of GPS Continuously Operating Reference Stations • Networks of geodetic control points -Permanently marked survey monuments (HPGN/HARN) • Tools - Geoid model, coordinate conversion & transformations etc. NSRS Components NSRS Components NATIONAL SPATIAL REFERENCE SYSTEM NATIONAL SPATIAL REFERENCE SYSTEM ACCURATE ACCURATE ---- cm accuracy on a global scale MULTIPURPOSE MULTIPURPOSE ---- Supports Geodesy, Geophysics, Supports Geodesy, Geophysics, Land Surveying, Navigation, Mapping, Charting and GIS Land Surveying, Navigation, Mapping, Charting and GIS activities activities ACTIVE ACTIVE ---- Accessible through Continuously Operating Accessible through Continuously Operating Reference Stations (CORS) and derived products Reference Stations (CORS) and derived products INTEGRATED INTEGRATED ---- Related to International services and Related to International services and standards (e.g. International Earth Rotation and standards (e.g. International Earth Rotation and Reference Systems Service, International GPS Service Reference Systems Service, International GPS Service etc.) etc.) FEDERAL GEODETIC SURVEYS COAST & GEODETIC SURVEY NATIONAL GEODETIC SURVEY 1900 - Astronomical observations & tie to Puerto Rico 1918 -1919 - Triangulation w/base-lines 1959 – Airport Surveys 1980 - Hydro Surveys 1993 & 2000 - Airport Surveys U.S. GEOLOGICAL SURVEY 1954 - Leveling of St. Thomas 1957 - Leveling of St. Croix GEODETIC DATUMS GEODETIC DATUMS Classical Classical Horizontal – 2 D (Latitude and Longitude) Vertical – 1 D (Orthometric Height) Contemporary Contemporary Practical Practical – 3 D (Latitude, Longitude and Ellipsoid Height) 3 D (Latitude, Longitude and Ellipsoid Height) Fixed and Stable Fixed and Stable – Coordinates seldom change Coordinates seldom change Scientific Scientific – 4 D (Latitude, Longitude, Ellipsoid Height, 4 D (Latitude, Longitude, Ellipsoid Height, Velocities) Velocities) – Coordinates change with time Coordinates change with time GEODETIC CONTROL GEODETIC CONTROL NETWORK OF MONUMENTED POINTS PRECISELY MEASURED IN ACCORDANCE WITH STANDARD PROCEDURES MEET ACCURACY SPECIFICATIONS ADJUSTED TO TIE TOGETHER DOCUMENTED FOR MULTIPLE USE Poured in place concrete post Stainless steel rod driven to refusal CORS SITES CORS SITES HORIZONTAL DATUMS PUERTO RICO DATUM Origin – Cardona Lighthouse Ellipsoid – Clarke 1866 NORTH AMERICAN DATUM 1983 Origin – Earth Mass Center Ellipsoid – Geodetic Reference System 1980 NOTE: North American Datum of 1927 (NAD 27) was never valid for VI & PR HORIZONTAL DATUMS VERTICAL DATUMS ST. THOMAS 1954 USGS Leveling Mean Low Water at Hassel Island ST. CROIX 1957 USGS Leveling Mean Sea Level at Fredericksted NOTE: National Geodetic Vertical Datum of 1929 (NGVD 29) was never valid for VI North American Vertical Datum of 1988 (NAVD 88) is not and will not be valid for VI ST CROIX GEODETIC CONTROL ST THOMAS GEODETIC CONTROL ST JOHN GEODETIC CONTROL ELLIPSOID ELLIPSOID - GEOID RELATIONSHIP GEOID RELATIONSHIP H h Ellipsoid GRS80 H = Orthometric Height (VIVD) N Geoid H = h - N h = Ellipsoidal Height (NAD 83) N = Geoid Height (GEOID 03) GEOID03 HORIZONTAL DATUMS National Geodetic Survey, Retrieval Date = JUNE 19, 2006 TV1548 *********************************************************************** TV1548 TIDAL BM - This is a Tidal Bench Mark. TV1548 DESIGNATION - TIDAL BM 1639 M TV1548 PID - TV1548 TV1548 STATE/COUNTY- VQ/VIRGIN ISLANDS TV1548 USGS QUAD - CENTRAL SAINT THOMAS (1982) TV1548 TV1548 *CURRENT SURVEY CONTROL TV1548 ___________________________________________________________________ TV1548* NAD 83(1997)- 18 20 01.30211(N) 064 55 15.34597(W) ADJUSTED TV1548* LOCAL TIDAL - 2.358 (meters) 7.74 (feet) GPS OBS TV1548 ___________________________________________________________________ TV1548 X - 2,567,098.806 (meters) COMP TV1548 Y - -5,485,384.394 (meters) COMP TV1548 Z - 1,993,464.947 (meters) COMP TV1548 LAPLACE CORR- 0.71 (seconds) DEFLEC99 TV1548 ELLIP HEIGHT- -39.87 (meters) (05/22/97) GPS OBS TV1548 GEOID HEIGHT- -42.64 (meters) GEOID03 TV1548 TV1548 HORZ ORDER - SECOND TV1548 ELLP ORDER - FOURTH CLASS I TV1548 TV1548.The horizontal coordinates were established by GPS observations TV1548.and adjusted by the National Geodetic Survey in May 1997.. TV1548 TV1548.The orthometric height was determined by GPS observations and a TV1548.high-resolution geoid model. Ellipsoid Height = - 39.87 m Geoid Height = -42.64 m Orthometric Hgt = 2.77 m VIRGIN ISLAND VERTICAL DATUM OF 200? Origin – MSL at NOAA Tides Gauges on each island VERTICAL DATUMS VERTICAL DATUMS CORS Continuously Operating Reference Station (CORS) NDGPS STATION Proposed – Roosevelt Roads, PR Caribbean Coverage Caribbean Coverage Current Estimated Coverage Proposed Caribbean Coverage Proposed Caribbean Coverage Guadeloupe Real-time coverage BVI Anguilla St Martin/St. Maarten Antiuga & Barbuda Saba St. Kitts Montserrat PROPOSED USVI CORS Proposed Installation – last week in July ‘06 UVI – St. Croix UVI – St. Thomas PROPOSED BVI CORS Vicinity of Fort Charlotte GOOD COORDINATION BEGINS WITH GOOD COORDINATES GEOGRAPHY WITHOUT GEODESY IS A FELONY