Determining g and N and the Impact on the New Vertical Datum for North America

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Determining g and N and the Impact on the New
Vertical Datum for North America
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• Daniel R. Roman, Ph.D.
• 2009 Workshop on
• Monitoring North American Geoid Change
• 21-23 OCT 2009 Boulder, CO

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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

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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
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Results 2006 Joint NGS and NRL Airborne Survey
Difference with upward-continued gravity field
Resulting changes in geoid from new gravity data
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Monitoring Change Terrestrial

• Uplift tectonic, GIA
• Subsidence sediment compaction, tectonic,
  water/oil pumping, GIA

Ave. Subsidence 5.2 0.9 mm/yr ??gt 3 yrs 1.56
cm ??gt 6.3 µGal change 7 mm/yr
wrt sl
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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

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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

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Scope of a North American Geoid/Vertical Datum

• Google Earth image showing Hawaii to Alaska to
  PR/VI

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Additional Information
The NGS 10 year plan (2008-2018) http//www.ngs.n
oaa.gov/INFO/NGS10yearplan.pdf
The GRAV-D Project Plan http//www.ngs.noaa.gov/G
RAV-D/pubs/GRAV-D_v2007_12_19.pdf
Socio-Economic Benefits of CORS and
GRAV-D http//www.ngs.noaa.gov/PUBS_LIB/Socio-Eco
nomicBenefitsofCORSandGRAV-D.pdf
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Additional Information

• NGS Contacts
• Dan Roman (PI), Dan.Roman_at_noaa.gov
• Vicki Childers (PM), Vicki.Childers_at_noaa.gov
• Dru Smith (Chief Geodesist), Dru.Smith_at_noaa.gov
• Always begin with your state advisor
• http//www.ngs.noaa.gov/ADVISORS/AdvisorsIndex.sht
  ml
• NGS Information Center
• Phone [phone]
• E-mail ngs.infocenter_at_noaa.gov
• GRAV-D Website
• http//www.ngs.noaa.gov/grav-d