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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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slide1
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

ITG-Goce:

Global GOCE SGG onlysolution

Regional gravityfieldrefinement

GRACE + GOCE

Regional gravityfieldrefinement

GRACE + GOCE + Altimetry

goce data
GOCE 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

signal

formal errors

median degree variances1
Median degree variances

signal

formal errors

Difference

ITG-Goce –

EIGEN-05c

median degree variances2
Median degree variances

signal

formal errors

Difference

ITG-Goce –

EIGEN-05c

Difference

ITG-Goce –

ITG-Grace2010s

regional gravity field recovery
Regional gravity field recovery

GRACE

GOCE

Regional refinement

Global reference solution

Spherical harmonics

Spherical splines

representation of geoid heights
Representation of geoid heights

The residual gravityfieldrepresentedby a linear combinationoflocalizingbasisfunctions

HarmonicSplines

shapecoefficients(expectedspectralcontent)

observation equations
Observation equations

Observation equations

GOCE

GRACE field

normal equations

Thisapproachhassimilaritiesto:

  • regularization
  • combinationwithspectralweighting
  • least squarescollocation

For the descripition of the theory see Eicker(2006)

regional gravity field recovery1
Regional gravity field recovery

GRACE

GOCE

Regional refinement

Global reference solution

Spherical harmonics

Spherical splines

regional gravity field recovery2
Regional gravity field recovery

GRACE

GOCE

Altimetry

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

Regional refinement

Global reference solution

Spherical harmonics

Spherical splines

altimetry
MDT

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

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

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 anomalies5
Results – gravity anomalies

Differences(RMS 8 mGal)

EGM2008

+

+

summary
Summary

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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