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New Coordinates for CORS Sites & Oregon Case Study The NGS Multi-Year CORS Solution and the evolution from NAD 83(C

New Coordinates for CORS Sites & Oregon Case Study The NGS Multi-Year CORS Solution and the evolution from NAD 83(CORS96)Epoch 2002 to NAD 83(2011)Epoch 2010. ODOT Surveyors Conference Mar 29th, 2011 By Mark L. Armstrong, PLS – NGS Oregon Advisor

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New Coordinates for CORS Sites & Oregon Case Study The NGS Multi-Year CORS Solution and the evolution from NAD 83(C

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  1. New Coordinates for CORS Sites &Oregon Case StudyThe NGS Multi-Year CORS Solution and the evolution from NAD 83(CORS96)Epoch 2002toNAD 83(2011)Epoch 2010 ODOT Surveyors Conference Mar 29th, 2011 By Mark L. Armstrong, PLS – NGS Oregon Advisor MYCS slides from Dr. Jake Griffiths, Dr. Giovanni Sella and the MYCS Team at NOAA/NGSOPUS-Net info. From Dr. Neil Weston

  2. A Little History • ‘Multi-year’ effort began 5 years ago • IGS proposed re-processing all data to re-compute station coordinates, orbits and EOPs from 1994-present • MYCS positions were derived from the reprocessing of the full 16 year time series (1994-2010) and a rigorous stacking of weekly estimates in a fully consistent, global framework. • 11 of these MYCS stations are in Oregon • NAD 83(2011)Epoch2010 is a new realization of NAD 83 based on this NGS Multi-Year CORS Solution (MYCS)

  3. Why Reprocess?Generally can’t continue to live in epoch 2002 • Generate fully consistent orbits, EOPs and CORS+global station coordinates using latest models and methods—existing history is inadequate for modern realizations of TRFs • longer data spans • absolute antenna calibrations • satellite transmitting and ground receiving antennas • new network design—added redundancy • Delaunay triangulation over global sites and CORS backbone • tie remaining CORS to backbone as stars • IERS 2003 Conventions generally implemented • updated model for station displacements due to ocean tidal loading • updated models for troposphere propagation delays • use current frame; first attempt to obtain a full history of products in a fully consistent framework • Contribute NGS reprocessed orbits, EOPs and global SINEX files to International GNSS Service (IGS) repro1 campaign • Generate CORS coordinates and velocities in global framework using new orbits, EOPs and global station coords Slide by J. Griffiths and the MYCS Team

  4. Frame Definition and Nomenclature • ITRF frame (global) multi-technique—vlbi, slr, doris, gnss • IGS frame (global) GNSS only • NAD frame (plate fixed) related to ITRF • Critical to pay attention to frame tags and epoch dates and antenna calibration values Frame Name Epoch Antenna PCV* Data Duration ITRF2000 1997.0 RelANTEX 1994.0-2002.0 ITRF00(NGS’ssoln) 1997.0 RelNGS ANTEX 1994.0-present NAD 83(CORS96) 2002.0 RelNGS ANTEX 1994.0-present ITRF2008 2005.0 Abs IGS05 ANTEX 1997.0-2009.5 IGS08 2005.0 Abs IGS08 ANTEX 1997.0-2009.5 IGS08 (NGS’stentative) 2005.0 Abs IGS08 ANTEX 1994.0-2010.5(ongoing) NAD 83(2011) (tentative) 2010.0 Abs IGS08 ANTEX 1994.0-2010.5 (ongoing)

  5. Slide by J. Griffiths and the MYCS Team

  6. West Coast Crustal Motion Horizontal velocities in the western U.S. relative to the North American Datum of 1983 as derived from geodetic observations. -Times 8 years (2002-2010) -As will be seen realized with NAD 83(2011)Epoch2010 (tent. name) Slide from R. Snay, NGS

  7. What now? • Reprocessing and ITRF re-alignment may take place again in 5-6 years • NAD 83(2011)Epoch2010 may be rolled into OPUS via an improved OPUS engine (OPUS-net)? • 2011 [CORS96a] positions are an improvement over CORS96 positions • Case Studies- NC, SC, AR, OR

  8. OPUS-Static vs. OPUS-Net (engines) • OPUS-Static • U.S. CORS Network • Fixed IGS ephemerides • Computes independent double differenced baseline solutions between the unknown and 3 CORS • Relative antenna models • Phase ambiguity integer fixing • Relative troposphere modeling • ITRF2000 reference frame • Average position solution • Peak – Peak error reported • OPUS-Net • U.S. CORS Network & IGS Global Network • Network approach • Consists of 3 nearby CORS + up to 12 CGPS from global IGS network • Absolute antenna models • SV & ground • Ocean tidal loading model • Satellite weighting • Relative troposphere modeling • ITRF2008 reference frame • Weighted least squares adjustment • Weighted mean and standard deviations reported at 95% OPUS-net info. From Dr. Neil Weston

  9. NGS Multi-Year CORS Solution (MYCS)A Case Study in OregonA comparison of how well the MYCS (CORS96a) coordinates fit in a network adjustment compared to CORS96 coordinates MYCS: NAD 83(CORS96a)Epoch 2010 vs. Published Datasheet (NGSIDB): NAD 83(CORS96)Epoch 2002 and OPUS-S Solution Mean (August 1-10, 2010): NAD 83(CORS96)Epoch 2002

  10. The network adjustment tests performed were an attempt to provide an independent comparison of the MYCS positions of eleven CORS stations against both the published datasheet positions (NGSIDB) and concurrent (same ten days August 1-10, 2010) averaged OPUS-Static solutions. * Stations in red no longer exist

  11. Oregon Case Study cont. • Baseline Processing • All baselines were processed, loop closures completed and then the project was saved and copied to 3 separate projects before continuing forward with the network adjustments in each of three NAD 83 datum realizations identified in the introduction. • Baselines that did not meet the loop closure requirement (0.030m horiz. and 0.050m vert.) were disabled. For the purposes of this investigation, performing the loop closure analysis provided informative statistics on the baseline vector interrelationships.

  12. MYCS in Oregon Final Computed MYCS CORS in Oregon - Will be held fixed in adjusting the ORGN

  13. Oregon CORS & CGPS ~31 CORS in Oregon ~139 CORS + CGPS -11 MYCS CORS

  14. Results Diagram shows plots of average error for 5 points constrained for each of the three realizations. The MYCS coordinates fit the baselines observed much better than the other two.

  15. Results – MYCS Network Adj. with 5 points constrained

  16. How does this affect Oregon CORS users?What changes will you see?

  17. West Coast Crustal Motion Horizontal velocities in the western U.S. relative to the North American Datum of 1983 as derived from geodetic observations. -Times 8 years (2002-2010) -As will be seen realized with NAD 83(2011)Epoch2010 (tent. name) Slide from R. Snay, NGS

  18. NAD 83(2011)Epoch 2010How will you cope with the change? • The ORGN Real-time Network may shift to this new NAD 83 realization sometime toward end August 2011? • For ACTIVE projects how will you cope? • Single base RTK from legacy project control? • Calibrate (localize)? • Shift your control to the new datum realization using OPUS-Net? • Convert your control coordinates with the OPUS Datum Conversion Tool for Oregon – • Currently under development and testing by Michael Olsen and ODOT

  19. Questions Mark Armstrong, PLS - Geodesist Oregon Advisor - NOAA/NOS/National Geodetic Survey Office: Oregon Department of TransportationGeometronics Unit4040 Fairview Industrial Dr. SE, Salem, OR 97302 503.986.3775 Office 503.986.3548 Fax 202.306.6716 Blackberry Email: mark.l.armstrong@noaa.gov

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