Temporal and spatial multiscale assessment of

gravity observations for Europe from satellite missions and

superconducting gravimeters

DFG German Priority Research Program 1257Mass Transport and Distribution in the Earth System

C. Kroner1, M. Abe2, J. Ihde3, G. Jentzsch1, J. Neumeyer2, M. Rothacher2, A. Weise1, H. Wilmes3, H. Wziontek3

1 Institute for Geosciences, Friedrich-Schiller-University Jena

2 GeoForschungsZentrum Potsdam

3 Federal Agency for Cartography and Geodesy (Frankfurt a. M.)

ObjectivesObjectives

Validation of satellite-derived temporal gravity variations by comparison with terrestrial observations deploying superconducting and absolute gravimeters

Improvement of modeling of continental water storage for Europe based on terrestrial and satellite-derived gravity field changes

related to first phase:

Network of Network of superconducting gravimeterssuperconducting gravimeters

superconducting gravimeters- high resolution- high long-term stability

- European stations selected data available for period of GRACE

mission present station cluster good knowledge of influence

factors good data quality AG observations available mostly equipped with permanent

GPSGMT

Vienna

Medicina

Moxa

Wettzell

MembachBad Homburg

Strasbourg

TasksTasks

to prove, SG data reflect large-scale gravity variations

‚regionalization‘ allowed

Homogenization of data processing

reprocessing according to fixed criteria

from GPS information on possible vertical deformations

drift assessment and calibration by repeated AG measurements

TasksTasks

consistent combination of satellite and terrestrial data

extraction of hydrological signal in gravity data

- separation of local and regional hydrological effects in SG observations

- reduction of further signals in SG data

comparison of hydrologically-induced gravity effects based on hydrological modeling with observations

ChallengesChallenges

different scales of observations

satellites:

temporal: monthly solutions (in future weekly?)

spatial: 500 – 2000 km

superconducting gravimeters:

temporal: 1s - 10s – data

spatial: „point observations“

Consistent combination Consistent combination Terrestrial gravity data Terrestrial gravity data

characteristics of terrestrial gravity observations

SG:

continuous

high resolution

drift

AG:

absolut

episodic

higher noise level

Consistent combination Consistent combination Terrestrial gravity dataTerrestrial gravity data

combination of SG and AG measurements: Bad Homburg, before

10

5

0

-5

µG

al

7

(Wziontek, 2007)

Consistent combination Consistent combination Terrestrial gravity dataTerrestrial gravity data

combination of SG and AG measurements: Bad Homburg, afterµ

Ga

l

5

0

-5

-10

µG

al

res

7

(Wziontek, 2007)

Consistent combination Consistent combination Terrestrial gravity dataTerrestrial gravity data

combination of SG and AG measurements: Wettzell, before

(Wziontek, 2007)

15

10

5

0

-5

-10

µG

al

7

Consistent combination Consistent combination Terrestrial gravity dataTerrestrial gravity data

combination of SG and AG measurements: Wettzell, afterµ

Ga

l

7

(Wziontek, 2007)

15

10

5

0

-5

-10

µG

al

res

Comparison Comparison GRACE – SG – hydrological GRACE – SG – hydrological

modelsmodels(Neumeyer et al., 2007)

Comparison Comparison GRACE – SG – hydrological GRACE – SG – hydrological

modelsmodels

5

4

3

2

1

0

-1

-2

-3

-4

-5

µG

al

SG

SG +local hydro. m odel

GRACE l fl=10

H96 l fl=10

W G HM l fl=10

Moxa / Germanyg

ravi

ty [

µg

al]

(Kroner, Naujoks, Krause, Neumeyer et al., 2007)

ConclusionsConclusions

combination of AG and SG observations

important information on instrumental properties

reliable, high-precision gravity time series available

global hydrology:

principle agreement between SG and GRACE observations as well as with hydrological models

certain discrepancies

reduction of local hydrological effects in terrestrial observations possible

What next?What next?

continuation of data sets

incorporation of GPS data for geometrical information

improved local hydrological reduction for all SG stations

EOF analyses

comparison with hydrological model for Europe?

Thank you

for

your attention!

Comparison Comparison GRACE – SG – hydrological GRACE – SG – hydrological

modelsmodels

(Kroner, Naujoks, Krause, Neumeyer et al., 2007)

Reduction of local hydrological effects: Moxa

based on hydrological model J2000 (Krause, 2001)

5

4

3

2

1

0

-1

-2

-3

-4

-5

Jan-03M ar-03

M ay-03Jul-03

Sep-03Nov-03

Jan-04M ar-04

M ay-04Jul-04

Sep-04Nov-04

Jan-05M ar-05

M ay-05Ju l-05

Sep-05Nov-05

Jan-06

µG

al

SG

SG +local hydro. m odel

G RACE l fl=10

H 96 l fl=10

W G HM l fl=10