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National Geodetic Survey – Continuously Operating Reference Stations &

National Geodetic Survey – Continuously Operating Reference Stations & Online Positioning User Service (CORS & OPUS) William Stone Southwest Region (UT, AZ, NM, NV) Geodetic Advisor william.stone@noaa.gov NOAA’s National Geodetic Survey User Conference San Diego – July 24, 2012.

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National Geodetic Survey – Continuously Operating Reference Stations &

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  1. National Geodetic Survey – Continuously Operating Reference Stations & Online Positioning User Service (CORS & OPUS) William Stone Southwest Region (UT, AZ, NM, NV) Geodetic Advisor william.stone@noaa.gov NOAA’s National Geodetic Survey User Conference San Diego – July 24, 2012

  2. “The location of anything is becoming everything.” Esri 2009 User Conference Opening Plenary “Geography is the platform for understanding the world.” Esri 2012 User Conference Opening Plenary

  3. National Spatial Reference System

  4. Continuously Operating Reference Station 36 33 42.15986 N 105 12 15.67754 W ellipsoid ht. 1857.765 m orthometric ht. 1876.145 m (NAD83(2011) / NAVD88) CORS Coordinates CORS GNSS Observation Data

  5. CORS Network • 1950 sites • 200 organizations

  6. CORS Coordinate History Time Series • Long-term • 60-day Red Butte (RBUT) CORS: 1997 - 2011 Red Butte (RBUT) CORS: Daily - Published IGS08

  7. Why CORS? • Provides direct tie to NSRS foundation • Eliminates recon, staff, equipment needs @ control points • Highly accurate – for all positioning requirements • Coordinates/velocities in NAD83 & global reference frame • Coordinates monitored daily & updated as required • Preparation for transition to new national datums (2022)

  8. CORS Applications • Surveying • GIS • Geophysics / Crustal Motion / Subsidence • Climate Change / Sea Level Rise • Flood Risk Analysis / Management • Precision Agriculture • Land Management • Meteorology (Water Vapor in Troposphere) • Space Weather (Free Electrons in Ionosphere) • Real-time Networks – NSRS Consistency • NGS: • Defining / Delivering NSRS • Precise Orbits

  9. Maintaining Coordinate Accuracy - the Multi-Year CORS Solution5 years in the making >>> new CORS coordinates & velocities • global tracking network: • satellite orbits (15-min intervals) • terrestrial framework • Earth Orientation (EOPs) • global station positions (weekly averages) Global Stations • U.S. CORS tied to global framework via single baselines • minimizes frame distortions from local effects in dense regional networks • 1994-2010.5 tracking history • 90 billion double-difference eqs. • relative >>> absolute antenna cals. • NAD83 (2011) epoch 2010.00 • IGS08 epoch 2005.0 • “few cm” change from previous Global Stations + CORS

  10. Change in NAD 83 Horizontal PositionNAD 83(2011)epoch2010.00– NAD 83(CORS96) epoch 2002.0 • Average shift: E = 0.05 cm  5.25 cm N = 2.12 cm 6.08 cm • combination of position and velocity differences • due mostly to updated velocities (including up to 8 more years of data) • plate movement in far West ID+MT+ND+SD+WY 1.7E / 0.5N cm WA+OR 4.4E / 5N cm East 1.4E / -0.2N cm CA+NV -10.8E / 14.4N cm UT+CO+NM+AZ 0.5E /1.0N cm

  11. CORS Coordinates – New Reference Frames IGS08 = International GNSS Service 2008 (GPS-only realization of ITRF2008) IGS08 Position >>> IGS08 Velocity >>> NAD83 Position >>> NAD83 Velocity >>> NAD83 (2011) epoch 2010.00 = North American Datum 1983 (2011 realization @ January 1, 2010)

  12. NGS Real-time GNSS Data Service (BETA)

  13. Online Positioning User Service (OPUS) • >15 min of L1/L2 GPS data >>> geodesy.noaa.gov/OPUS • OPUS-RS (Rapid Static) ----15 min to 2 hours • OPUS-S (Static) ---- 2 to 48 hours • solution via email - in minutes • options: publishing; OPUS-Projects (under development/testing) • now using NAD83(2011) epoch 2010.00 & IGS08 epoch 2005.0 (from MYCS) • now using GEOID12 for orthometric height computation • fast, easy, consistent access to NSRS

  14. Online Positioning User Service (OPUS) Submission Page GPS file antenna antenna height e-mail extended solution in/exclude CORS SPCS zone project profile publish OPUS-RS or OPUS-Static (15 min-2 hr) (2-48 hr)

  15. OPUS Solution Report

  16. OPUS-RS Accuracy Estimator Tool

  17. OPUS – Datasheet Publishing • Publication Criteria: • NGS-calibrated GPS antenna • > 4 hour data span (OPUS-S) • > 70% observations used • > 70% fixed ambiguities • < 0.04m H / 0.08m V peak-to-peak • Applications: • GPS on BMs (geoid modeling) • PLSS / GCDB • Data-sharing/archive

  18. CORS & OPUS INFO • CORS Site Guidelines • Future CORS Sites • CORS Newsletter • FAQs • Papers • Bibliography • Presentations • Contact Info • GPS Calendar • Resource Links • Coordinates • About OPUS geodesy.noaa.gov/CORS (& …/OPUS)

  19. CORS MonographCORS and OPUS for Engineers: Tools for Surveying and Mapping Applications • sponsored by ASCE and NGS • available on ASCE website • useful to CORS & OPUS users working in many different types of GPS applications • OPUS troubleshooting tips

  20. see The American Surveyor vol 8 (no. 5,6,7)

  21. NGS Real-time Guidelines: Single-base and Network

  22. National Geodetic Survey Geodetic Advisors Geodetic Advisor Contact Info: http://geodesy.noaa.gov/ADVISORS/AdvisorsIndex.shtml

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