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This workshop discusses the plan to redefine the US Vertical Datum and the projected impact on monitoring changes over time using airborne gravity data. The workshop covers program elements, cost, and collaboration with other agencies and countries. Additional information and contacts are provided.
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Determining ġ and N and the Impact on the New Vertical Datum for North America . Daniel R. Roman, Ph.D. 2009 Workshop on Monitoring North American Geoid Change 21-23 OCT 2009 Boulder, CO
NGS’ Plan: GRAV-D Official NGS policy: Re-define the US Vertical Datum by creating a new gravimetric geoid 10 year program Two Major Program Elements Airborne Gravity “Snapshot” for Baseline Long Term Monitoring of Temporal Changes Projected program cost: $38.5M over 10 years • Official NGS policy: • Re-define the US Vertical Datum by creating a new gravimetric geoid • 10 year program • Two Major Program Elements • Airborne Gravity “Snapshot” for Baseline • Long Term Monitoring of Temporal Changes • Projected program cost: $38.5M over 10 years • Official NGS policy: • Re-define the US Vertical Datum by creating a new gravimetric geoid • 10 year program • Two Major Program Elements • Airborne Gravity “Snapshot” for Baseline • Long Term Monitoring of Temporal Changes • Projected program cost: $38.5M over 10 years
Static Snapshot: Airborne Provides intermediate wavelength gravity data Reconciles terrestrial datasets Fills in spatial gaps in the littoral region Terrestrial gravity points 20-100 km gravity gaps along coast Ship gravitytracks New Orleans
Results: 2006 Joint NGS and NRL Airborne Survey Difference with upward-continued gravity field Resulting changes in geoid from new gravity data
Monitoring Change: Terrestrial Uplift: tectonic, GIA Subsidence: sediment compaction, tectonic, water/oil pumping, GIA Ave. Subsidence: 5.2 ± 0.9 mm/yr ――> 3 yrs: 1.56 cm ――> 6.3 μGal change ~7 mm/yr wrt sl Dokka, et al. (2006) GRL Dokka, et al. (2006) GRL
Collaboration • Other U.S. Agencies: Provide a common national model • NGA • USGS • USACE • FEMA • To better tie work of the whole of government • Other Countries: Provide a common regional model • Canada • Mexico • Caribbean nations • Geoid is long wavelength • Transparency across borders with a seamless model
Collaboration • International Organizations • International Association of Geodesy • North American Geoid: • IAG CP 2.2 • Chair: Roman • Canada and Mexico are members • Theoretical Improvements: • IAG IC-SG8 • Chair: Wang • Membership from around the world • Ties with other IAG work groups • F.I.G • Working to define how new vertical datum will be implemented and accessed
Scope of a North American Geoid/Vertical Datum • Google Earth image showing Hawaii to Alaska to PR/VI
Additional Information The NGS 10 year plan (2008-2018) http://www.ngs.noaa.gov/INFO/NGS10yearplan.pdf The GRAV-D Project Plan http://www.ngs.noaa.gov/GRAV-D/pubs/GRAV-D_v2007_12_19.pdf Socio-Economic Benefits of CORS and GRAV-D http://www.ngs.noaa.gov/PUBS_LIB/Socio-EconomicBenefitsofCORSandGRAV-D.pdf
NGS Contacts: Dan Roman (PI), Dan.Roman@noaa.gov Vicki Childers (PM), Vicki.Childers@noaa.gov Dru Smith (Chief Geodesist), Dru.Smith@noaa.gov Always begin with your state advisor: http://www.ngs.noaa.gov/ADVISORS/AdvisorsIndex.shtml NGS Information Center Phone: (301) 713-3242 E-mail: ngs.infocenter@noaa.gov GRAV-D Website http://www.ngs.noaa.gov/grav-d Additional Information
