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Geoid Modeling, GRAVD and Height Mod

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... Models (e.g., USGG2009) and Conversion Surfaces using GPS on BM ... Conversion Surface model of systematic misfit derived from BM's in IDB ... 'Time ... – PowerPoint PPT presentation

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Title: Geoid Modeling, GRAVD and Height Mod


1
Geoid Modeling, GRAV-D and Height Mod
2
Why make a new vertical datum?
Courtesy of Dr. Dennis Milbert
20 FEB 2009 Salt Lake City, UT
ACSM-MARLS-UCLS-WFPS Conference 2009
2
3
Vertical Shift due the National Readjustment of
2007
20 FEB 2009 Salt Lake City, UT
ACSM-MARLS-UCLS-WFPS Conference 2009
3
4
Hybrid Geoid Height Models (e.g., GEOID09),
Gravimetric Geoid Height Models (e.g., USGG2009)
and Conversion Surfaces using GPS on BM data

Earths Surface
Ellipsoid
Hybrid Geoid
Gravimetric Geoid
  • Gravimetric Geoid systematic misfit to BMs but
    best fits true heights
  • Hybrid Geoid converted to fit local BMs, so
    best fits NAVD 88 heights
  • Conversion Surface model of systematic misfit
    derived from BMs in IDB

5
(Beta) GPSBM 2009 for CONUS
20 FEB 2009 Salt Lake City, UT
ACSM-MARLS-UCLS-WFPS Conference 2009
5
6
USGG2009 (Beta)
GEOID09 (Beta)
20 FEB 2009 Salt Lake City, UT
ACSM-MARLS-UCLS-WFPS Conference 2009
6
7
Extent of Gravity Coverage Shown are the
differences between NGSIDB value and EGM08 model
20 FEB 2009 Salt Lake City, UT
ACSM-MARLS-UCLS-WFPS Conference 2009
7
8
GRAV-D Gravity for the Redefinition of the
American Vertical Datum
  • Official NGS policy as of Nov 14, 2007
  • 38.5M over 10 years
  • Airborne Gravity Snapshot
  • Static Geoid
  • Absolute/Satellite Gravity Tracking
  • Time Dependent Geoid
  • Re-define the Vertical Datum (using gravimetric
    geoid as reference surface) of the USA by 2017

http//www.ngs.noaa.gov/GRAV-D/
9
A North American Geoid
20 FEB 2009 Salt Lake City, UT
ACSM-MARLS-UCLS-WFPS Conference 2009
9
10
For a more thorough discussion,see the
USGG2009/GEOID09 session later today
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