Geoid Modeling, grav-d and Height Mod

Geoid Modeling, GRAV-D and Height Mod

Gravimetric Geoid systematic misfit to BM’s but best fits “true” heights

• 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

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

For a more thorough discussion, see the USGG2009/GEOID09 session later today