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Beyond GEOID12: Implementing a New Vertical Datum for North America

Beyond GEOID12: Implementing a New Vertical Datum for North America. Daniel R. Roman, Ph.D. Neil D Weston, Ph.D. Approximate level of error known to exist in the NAVD 88 zero elevation surface. Why isn’t NAVD 88 good enough anymore?. Available Tide Gauges. SST, TBM’s and the Geoid.

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Beyond GEOID12: Implementing a New Vertical Datum for North America

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  1. Beyond GEOID12: Implementing a New Vertical Datum for North America Daniel R. Roman, Ph.D. Neil D Weston, Ph.D.

  2. Approximate level of error known to exist in the NAVD 88 zero elevation surface Why isn’t NAVD 88 good enough anymore? F.I.G. Working Week 2012 6-10 May 2012 Rome, Italy

  3. Available Tide Gauges F.I.G. Working Week 2012 6-10 May 2012 Rome, Italy

  4. SST, TBM’s and the Geoid • P,T,S ≠ constant/uniform • Geoid + SST = LMSL (as seen at tide gauge) SST/MODT Local MSL Geoid = “Global” MSL surface F.I.G. Working Week 2012 6-10 May 2012 Rome, Italy

  5. SST (MODT) Models Foreman et al. 2004 Thompson-Demiorov 2006 F.I.G. Working Week 2012 6-10 May 2012 Rome, Italy

  6. Tide Gauge comparisons limited to where SST models exist 62,636,856.00 m2/s2 F.I.G. Working Week 2012 6-10 May 2012 Rome, Italy

  7. Current GRAV-D Coverage GRAV-D: Gravity for the Redefinition of the American Vertical Datum F.I.G. Working Week 2012 6-10 May 2012 Rome, Italy

  8. Summary • NAVD 88 is insufficient to meet cm-level needs • Must use highly accurate gravimetric geoid • New W0 best fits most Tide Gauges • SST models remove significant variability in LMSL • Same W0 value adopted by IAU and IERS • Neglects Arctic but also Mexico & Caribbean F.I.G. Working Week 2012 6-10 May 2012 Rome, Italy

  9. Summary • U.S.A & Canada have agreed to use this W0 • Will serve as Canadian Vertical Datum in 2013 • It is the likely value for U.S. in 2022 • GRAV-D aerogravity will bridge gap • Satellite gravity models will provide unification • Surface gravity & DEM’s give high frequency • Aim is for cm-level accuracy in geoid and GNSS F.I.G. Working Week 2012 6-10 May 2012 Rome, Italy

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