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Regional high resolution geoid and mean sea surface topography determination by a combination of GOCE, GRACE and altimetry data. Torsten Mayer-Gürr, Annette Eicker, Judith Schall Institute of Geodesy and Geoinformation University of Bonn. Overview. ITG- Goce : Global GOCE SGG only solution.

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Regional high resolution geoid and mean sea surface topography determination by a combination of GOCE, GRACE and altimetry data

Torsten Mayer-Gürr, Annette Eicker, Judith Schall

Institute of Geodesy and GeoinformationUniversity of Bonn


Overview
Overview topography determination by a combination of GOCE, GRACE and altimetry data

ITG-Goce:

Global GOCE SGG onlysolution

Regional gravityfieldrefinement

GRACE + GOCE

Regional gravityfieldrefinement

GRACE + GOCE + Altimetry


Goce data
GOCE data topography determination by a combination of GOCE, GRACE and altimetry data

ITG-Goce (preliminaryresults)

1 monthofdata:

- gradiometerdata

- starcameradata

- orbitdata

Computedwiththeshortarcmethod:

Foreachshortarc (15 min)

- fullvariancecovariance

- biasparameterforeach SGG component

- SST contributionismissingyet


Median degree variances
Median degree variances topography determination by a combination of GOCE, GRACE and altimetry data

signal

formal errors


Median degree variances1
Median degree variances topography determination by a combination of GOCE, GRACE and altimetry data

signal

formal errors

Difference

ITG-Goce –

EIGEN-05c


Median degree variances2
Median degree variances topography determination by a combination of GOCE, GRACE and altimetry data

signal

formal errors

Difference

ITG-Goce –

EIGEN-05c

Difference

ITG-Goce –

ITG-Grace2010s


Regional gravity field recovery
Regional gravity field recovery topography determination by a combination of GOCE, GRACE and altimetry data

GRACE

GOCE

Regional refinement

Global reference solution

Spherical harmonics

Spherical splines


Itg grace2010s gravity anomalies
ITG-Grace2010s gravity anomalies topography determination by a combination of GOCE, GRACE and altimetry data


Itg grace2010s gravity anomalies1
ITG-Grace2010s gravity anomalies topography determination by a combination of GOCE, GRACE and altimetry data


Representation of geoid heights
Representation of geoid heights topography determination by a combination of GOCE, GRACE and altimetry data

The residual gravityfieldrepresentedby a linear combinationoflocalizingbasisfunctions

HarmonicSplines

shapecoefficients(expectedspectralcontent)


Observation equations
Observation equations topography determination by a combination of GOCE, GRACE and altimetry data

Observation equations

GOCE

GRACE field

normal equations

Thisapproachhassimilaritiesto:

  • regularization

  • combinationwithspectralweighting

  • least squarescollocation

For the descripition of the theory see Eicker(2006)


Results gravity anomalies
Results – gravity anomalies topography determination by a combination of GOCE, GRACE and altimetry data

ITG-Grace2010s

+


Regional gravity field recovery1
Regional gravity field recovery topography determination by a combination of GOCE, GRACE and altimetry data

GRACE

GOCE

Regional refinement

Global reference solution

Spherical harmonics

Spherical splines


Regional gravity field recovery2
Regional gravity field recovery topography determination by a combination of GOCE, GRACE and altimetry data

GRACE

GOCE

Altimetry

T/P, ERS 1/2, ...

Regional refinement

Global reference solution

Spherical harmonics

Spherical splines


Altimetry

MDT topography determination by a combination of GOCE, GRACE and altimetry data

Sea surface

SSH

Geoid

Geoid height

Ellipsoid

Altimetry

Altimetrydata(T/P, ERS 1/2, …)

Altimetrycanimprovetheresolutionofthe GRACE/GOCE geoid.

But:

Altimeter satellitesmeasurestheseasurfaceheight (SSH) and not thegeoidheight

=> Combinedestimationofgeoidand MDT


Altimetry1

MDT topography determination by a combination of GOCE, GRACE and altimetry data

Sea surface

SSH

Geoid

Geoid height

Ellipsoid

Altimetry

Altimetrydata(T/P, ERS 1/2, …)

Observation equation

meansea surfaceheight

mean dynamictopography

geoidheight

=

+

Localizingbasisfunctionsadaptedtothespectralcontenentofthe MDT

Localizingbasisfunctionsadaptedtothespectralcontenentofthe residual gravityfield


Observation equations1
Observation equations topography determination by a combination of GOCE, GRACE and altimetry data

Complete observation equations

Altimetry

GOCE

GRACE field

apriori (stochastical)information from MDT

gravity

MDT

Relative weighting of each set of observations by thevariance component estimation method (VCE)(Koch & Kusche 2001)


Results gravity anomalies1
Results – gravity anomalies topography determination by a combination of GOCE, GRACE and altimetry data

+

+

+


Results mean dynamic topography
Results – mean dynamic topography topography determination by a combination of GOCE, GRACE and altimetry data


Results gravity anomalies2
Results – gravity anomalies topography determination by a combination of GOCE, GRACE and altimetry data

+

+

+


Results gravity anomalies3
Results – gravity anomalies topography determination by a combination of GOCE, GRACE and altimetry data

+

+


Results gravity anomalies4
Results – gravity anomalies topography determination by a combination of GOCE, GRACE and altimetry data

EGM2008

+

+


Results gravity anomalies5
Results – gravity anomalies topography determination by a combination of GOCE, GRACE and altimetry data

Differences(RMS 8 mGal)

EGM2008

+

+


Summary
Summary topography determination by a combination of GOCE, GRACE and altimetry data

GOCE improves the gravity fieldcompared to GRACE in the high degrees

Our first GOCE solution (ITG-Goce) fits better toITG-Grace2010s than to EIGEN-05Cin the medium degrees (n=90…150)

Refinenemtof

GRACE + GOCE gravityfield

withAltimetry (T/P, ERS 1/2, ...)leadsto:

  • Regional highresolution Geoid

  • Estimationofthemeandynamictopography (MDT)

Geoid

Topography


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