Integration of Gravity Data Into a Seamless Transnational Height

Model for North AmericaDaniel Roman, Marc Véronneau, David Avalos, Xiaopeng Li, Simon

Holmes, and Jianliang Huang

Session 5: Paper S5-075

Gravity for the Redefinition of the American Vertical Datum (GRAV-D)• Overview• Not just aerogravity – Use to clean/salvage two

million terrestrial data– Makes improved geoid– Must use satellite data– Yields a vertical datum

• Neighboring countries– Must develop a North

America Model

Session 5 Paper S5-075 1730 10 OCT 2012

Gravity Geoid and Height Systems Venice, Italy 09-12 OCT 2012 2

GRAV-D Status

Session 5 Paper S5-075 1730 10 OCT 2012

Gravity Geoid and Height Systems Venice, Italy 09-12 OCT 2012 3

TX09

Discussion of GRAV-D intent

• Goal of a cm-level accurate geoid• Must meld different gravity sources• To do this: must resolve systematic

errors in gravity observations– Compare aerogravity to satellite data – Constrain aerogravity to GRACE/GOCE– Combined satellite & airborne gravity field

model- somewhere between deg 100-250– Use aerogravity to fix errors and bridge

spectral gap with terrestrial surveys– Derive shortest wavelengths from high

resolution terrain and density models– Develop a seamless gravity field to 10,800

• Rigorously transform to generate geoid heights and DoV’s

4

1.E-08

1.E-06

1.E-04

1.E-02

1.E+00

1.E+02

1.E+04

satellite models (GRACE/GOCE)

terrestrial gravity

airborne gravity

Var

ian

ce (

m2)

Satellite-AirborneTransition Band

Airborne-Terrestrial Transition Band

Session 5 Paper S5-075 1730 10 OCT 2012

Gravity Geoid and Height Systems Venice, Italy 09-12 OCT 2012

ATTB: 150-450 (100-540 with tapers)

EGM2008540 (GOCO03S) – EGM2008540 (GRACE)

ATTB: Degrees 150-450 (100-540)

Historical surface data agreements with EGM08

More clear Systematic features in Historical surface data, focus on long wavelength

More clear short wavelength Systematic features in Historical surface data are detected after adding airborne information

Line 3613

Line 5357

Line 2144

Line 5162

EGM2008 (GRACE Only) EGM2008 (GOCO03S) GOCO03S+Aerogravity

EGM2008 (GRACE Only) EGM2008 (GOCO03S) GOCO03S+Aerogravity

Summary

• GOCO03S benefits EGM2008• Systematic errors in terrestrial data still exist• Such errors lead to systematic geoid errors• Must resolve these for cm-level accuracy• Aerogravity in Texas differs from terrestrial at

the 3-5 mGal range• Can be discerned in some terrestrial profiles• Data cleaning will be required to resolve theseSession 5 Paper S5-075 1730 10 OCT 2012

Gravity Geoid and Height Systems Venice, Italy 09-12 OCT 2012 13

Alaska examples

QUESTIONS?

Session 5 Paper S5-075 1730 10 OCT 2012

Gravity Geoid and Height Systems Venice, Italy 09-12 OCT 2012 15