1. Progress towards a common North American Geoid in 2012 Daniel Roman, Yan Wang & Xiaopeng Li National Geodetic Survey Geosciences Research Division

2. Considerations for Unification Datum surface (W 0 selection) GNSS Reference Frame EGM Reference Model Kernel Modification USGG2012 – CGG2010 Comparisons – Gravity data sets – Techniques GRAV-D

3. Agreement on W 0 Value Session G1B, 1300-1500 Tuesday, 05 June 2012 Regional and global geoid based vertical datums II: Progress towards a common North American Geoid in 2012 3 of

4. Tide Gauge comparisons limited to where SST models exist TSC04C: Heights, Geoid, & Gravity Paper 5691, 08 May 2012, 0900 F.I.G. Working Week 2012 6-10 May 2012 Rome, Italy 4 62,636,856.00 m 2 /s 2

5. Goemetric Reference Frame NAD83(CSRS) vs NAD83(2011) PERSOMM Rich Snay Should agree Differing SOP’s may cause inconsistencies in velocities and positional coordinates Must also track ref. epoch U.S. set epoch at 2010.0 Canada also tracks GIA closely NAD83(CSRS) vs NAD 83(2022) U.S. may have to keep “NAD 83” name for legal reasons It will effectively be IGS2020 or ITRF2020 Likely fixed at a specific epoch (not dynamic) HTDP to transform Use these to access GNSS- derived orthometric heights

6. Spectrally Combined Reference Model

7. Degree Kernel Modification ModelAlaskaCONUS µ (m)σ(m)µ (m)σ(m) EGM20081.2750.245-0.00980.0636 USGG2009 (AK 360/CONUS 120)1.2670.242-0.00990.0632 TGM040912d+RTM+kernel1201.2540.242-0.00950.0625 TGM040912d+RTM+kernel1801.2530.240-0.00950.0623 TGM040912d+RTM+kernel2401.2550.242-0.00950.0619 TGM040912d+RTM+kernel3001.2550.242-0.00950.0621 TGM040912d+RTM+kernel3601.2540.241 -- TGM040912d+RTM+kernel4801.2570.243 -- TGM040912d+RTM+kernel10001.2580.241 --

8. USGG2012 – CGG2010 Differences

10. USGG2012 – USGG2009 Differences

12. USGG2012 – USGG2003 Differences

14. GRAV-D Status Map Key Green: Available data and metadata Blue: Data being processed, metadata may be available Orange: Data collection underway White: Planned for data collection

15. Aerogravity Production Timeline AK08– Fall 2012 AK09-- Fall 2012 PV09-- Summer 2012 NY11-- Summer 2012 AK10-1 -- Fall 2012 AK10-2 -- Fall 2012 AK10-3 -- Fall 2012 IN11-- Fall 2012 AK11 -- Winter 2013 IN12 -- Winter 2013 CA11-- Spring 2013 MN12-- Spring 2013 TX12-- Summer 2013 ME12-- Summer 2013

16. Questions? Daniel R. Roman, Ph.D., GRAV-D P.I., Geoid Team Lead Geosciences Research Division, National Geodetic Survey, NOS, NOAA +1-301-713-3202 x161 dan.roman@noaa.gov