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GEOID MODELING UPDATE

GEOID MODELING UPDATE. 30 April 2013 HT MOD Work Shop Daniel R. Roman, Ph.D. Outline. USGG2012 GEOID12A GEOID12A Error Map GRAV-D GSVS 11 & 14. USGG2012. GOCO02S + EGM2008 + 3”-5’ RTM + ~ two million surface gravity ||/ / One- arcminute (1’) nodes

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GEOID MODELING UPDATE

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  1. GEOID MODELING UPDATE 30 April 2013 HT MOD Work Shop Daniel R. Roman, Ph.D.

  2. Outline • USGG2012 • GEOID12A • GEOID12A Error Map • GRAV-D • GSVS 11 & 14

  3. USGG2012 • GOCO02S + EGM2008 + 3”-5’ RTM + ~ two million surface gravity \||/ \/ • One-arcminute (1’) nodes • IGS08-based reference • GRS-80 ellipsoid shell • W0 = 62,636,855.69 m2/s2 Note: this is not the value adopted with Canada Min =-52.53 m Max = 3.47 m Ave = -29.84 m SD = 10.35 m GOCO02S is a combination of GRACE, GOCE, CHAMP and SLR Goiginger H., Rieser D., Mayer-Guerr T., Pail R., Schuh W.-D., Jäggi A., Maier A., GOCO Consortium (2011): The combined satellite-only global gravity field model GOCO02S. European Geosciences Union General Assembly 2011, Wien, 04.04.2011.

  4. h h h h H h H H H N N N H N N Hybrid Geoid Height Models (e.g., GEOID12A), Gravimetric Geoid Height Models (e.g., USGG2012) and Conversion Surfaces using GPS on BM data Earth’s Surface • Gravimetric Geoid systematic misfit to BM’s but best fits “true” heights • Hybrid Geoid“converted” to fit local BM’s, so best fits NAVD 88 heights • Conversion Surface model of systematic misfit derived from BM’s in IDB Ellipsoid Hybrid Geoid Gravimetric Geoid

  5. GEOID12A Datums

  6. Distribution of OPUSDBBM12

  7. GEOID12A – GEOID09 • GEOID12 • Biggest changes • Gulf Coast • Ellipsoid – NA2011 • Vertical – HT MOD 2012 • Spreading East/West • Minor changes central part • Wisconsin • Mountains in West (RTM) • Scattered GPS/OPUS BM’s • Changes are 1/3 those of GEOID09-GEOID03 GEOID12A Min = -50.71 m Max = 3.31 m Ave = -29.48 m SD = 10.06 m GEOID09 Min = -50.68 m Max = 3.44 m Ave = -29.47 m SD = 10.05 m GEOID12A – GEOID09 Min = -44.5 cm Max = 54.5 cm Ave = -1.3 cm SD = 5.1 cm GEOID09 – GEOID03 Min = -226.9 cm Max = 171.8 cm Ave = 2.0 cm SD = 16.6 cm

  8. GEOID12A Error Grid

  9. GRAV-D • Vertical Datum surface chosen with Canadians W0 = 62,626,856.0 m2/s2 • >25% flown • Data shared with Canadians over GL & AK • Data shared with Mexico in SW • First attempts made to clean terrestrial gravity Map Key - Airborne Gravity Data Green: Available data and metadataBlue: Data being processedOrange: Data collection underwayWhite: Planned for data collection

  10. GSVS 11 • Goal: to provide relative geoid height from field observations at an accuracy of ±1.4 cm along a line of 325 km • Data Collected: • Terrestrial gravity • Absolute • Relative • Gradients • Aerogravity (TX09 flights) • Astrogeodetic DoV • GPS (processed multiple ways) • Leveling • GPS & leveling minimally constrained • Outcome: sub-cm comparison along the profile (GPS/leveling vs. gravimetric geoid)

  11. GSVS 14 Line Goal: Same as GSVS 11 Region: Moderate terrain Data: Same as GSVS 11 Timeline: Pushed to the right into FY 14

  12. GRAV-D: Future Work • Continue aerogravity collection • NGS and contractors • UAS • Refinement of aerogravity processing SOP’s • Regional Collaboration • CGG2013 – Emphasis of Great Lakes • Mexican gravity – absolute sites • IGLD 15 • Comparisons over Rockies

  13. GRAV-D: Future Work (Cont.) • Geoid Modeling • Cleaning of terrestrial gravity data • Production of seamless gravity field models • Adoption of more rigorous geoid modeling SOP’s • Comparisons • With CGG2013 (and follow-on models) • With GGM2010 (and follow-on models) • SIRGAS & WHS • Tidal Bench Marks/MSSH (LMSL = MSL + MODT) • GSVS 11/14/??

  14. GRAV-D: Future Work (Cont.) • Completion: • Aerogravity: 2020 to 2022 • Geoid Modeling: 2022 • Implementation: • Interim models on GRAV-D website • Future USGG20xx may adopt aerogravity • Dependent on impact of incomplete coverage • Eventually will be a geoid height model in same ellipsoidal reference frame as geometric datum • Akin to the output currently provided by OPUS

  15. Questions? Geoid Modeling Gravity Collections www.ngs.noaa.gov/GRAV-D Dr. Vicki Childers GRAV-D P.M., Aerogravity Ms. Monica Youngman Asst. GRAV-D P.M., Project Lead Dr. Theresa Damiani Kinematic GPS, Aerogravity Ms. Sandra Preaux Aerogravity Theory & Practice Mr. Mark Eckl Chief OAD, Abs. & Rel. Gravity • www.ngs.noaa.gov/GEOID • Dr. Yan Wang • Geoid Theory, Physical Geodesy • Dr. Dan Roman • GRAV-D P.I., Physical Geodesy • Dr. Simon Holmes • EHM/SHM, Physical Geodesy • Dr. Xiaopeng Li • GPS/INS, Physical Geodesy

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