mgal - Technische Universität München

Report
Impact of GOCE on lithospheric modelling in
active plate margins
ESA Living Planet Symposium 2013
Edinburgh, 10-09-2013
Michael Hosse(1), Roland Pail(1), Martin Horwath(1),
Tetjana Romanyuk(1), Ben Gutknecht(2), Nils Köther(2)
(1)
Technische Universität München, Institute of Astronomical and Physical
Geodesy
(2) Christian-Albrechts-Universitaet Kiel, Institute of Geosciences, Department
of Geophysics
About IMOSAGA
Integrated Modelling of Satellite and Airborne Gravity data
of Active plate margins
Part of DFG programme „Mass transport and mass
distribution in the Earth system“ SPP 1257
Tight cooperation and interaction of geodetic and
geophysical expert groups
ESA Living Planet Symposium 2013,
Edinburgh, September 09-13 2013
Project Objectives
Investigation of active continental
margins for
– Density distribution in 3D
– Dynamic Structures (Finite Elements)
– Rigidity
by usage of
– Satellite gravimetry and gradiometry
(GOCE, GRACE)
– Terrestrial gravimetry
– Combined gravity
models (Least Squares
Collocation LSC)
ESA Living Planet Symposium 2013,
Edinburgh, September 09-13 2013
Motivation
revised gravity field information in
geophysically interesting areas
impact on static and dynamic
lithospheric models
(Götze et al.,
2011)
ESA Living Planet Symposium 2013,
Edinburgh, September 09-13 2013
Datasources – Terrestrial data
~ 175000 point measurements
(gabs, FA, BA) from different
sources collected during the past
30 years
widely spread over South
America
No informations available about
used instruments and methods
No accuracies available
ESA Living Planet Symposium 2013,
Edinburgh, September 09-13 2013
Datasources – Digital Terrain Model
Used datasets:
- 3“ (land only)
- 30“ (with bathymetry)
Available at:
http://tethys.eaprs.cse.dmu.ac.uk/ACE2/
ESA Living Planet Symposium 2013,
Edinburgh, September 09-13 2013
Validation of terrestrial data – Heights
Differences to ACE2
– Max.: 915 m
– Min.: -1365 m
– Mean: 2.8 m
– STD: 53.7m
ESA Living Planet Symposium 2013,
Edinburgh, September 09-13 2013
Validation of terrestrial data – Heights
Differences to ACE2
– Filtered at 80m
(~25 mGal Free-Air)
–
–
–
–
Max.: 80 m
Min.: -80 m
Mean: 0.4 m
STD: 25,1 m
ESA Living Planet Symposium 2013,
Edinburgh, September 09-13 2013
Datasources - Satellite gravity data
The satellite only model GOCO03s
GRACE:
7.5 years
GOCE:
18 months
SLR:
5 years, 5 sat
CHAMP:
8 years
Constrains:
Kaula, deg > 180
Available at:
http://www.goco.eu/
(Mayer-Gürr et.al: The new combined
satellite only model GOCO03s, 2012)
ESA Living Planet Symposium 2013,
Edinburgh, September 09-13 2013
Validation of terrestrial data - Gravity
Difference terrestrial – GOCO03S (d/o 250)
[mgal]
Difference terrestrial – EGM2008 (d/o 2190)
GOCO03S EGM2008
Max. Diff
216.66
102.59
Min. Diff
-325.72
-303.86
Mean
-6.64
-1.45
RMS
24.08
10.94
ESA Living Planet Symposium 2013,
Edinburgh, September 09-13 2013
Calculation schema
ESA Living Planet Symposium 2013,
Edinburgh, September 09-13 2013
Calculation schema
ESA Living Planet Symposium 2013,
Edinburgh, September 09-13 2013
Calculation schema
ESA Living Planet Symposium 2013,
Edinburgh, September 09-13 2013
Preprocessing terrestrial data
Dimension of normal equation
depends on number of
observations → restriction of
points
Distribution of points is very
inhomogeneous
Calculated for each of the 53.000 stations in study area
Selected the stations with the smallest value q within a
radius of 3 km
ESA Living Planet Symposium 2013,
Edinburgh, September 09-13 2013
Least Squares Collocation (LSC)
… signal covariances, derived from covariance model fitted
consistently to (reduced) gravity gradients and (reduced) terr. data
… noise covariances: - terrestrial data: empirical
- satellite gravity data: covariance propagation
(including omission error !!!)
BIG advantage: we
obtain error estimates:
ESA Living Planet Symposium 2013,
Edinburgh, September 09-13 2013
Input data & stochastic models
mGal
60
40
20
0
-20
-40
Satellite data (reduced):
• Synthetized from GOCO03S, on grid
• Error information:
- commission part: derived by full covariance propagation from GOCO03S variance-covariance matrix
- omission part (> d/o 250) : derived by variance
propagation from EGM2008 variances
-60
mGal
60
40
20
0
-20
Terrestrial & altimetry data:
• Terrestrial data: 9910 points, irregularly distributed
• Altimetry data (DTU10): 2353 points, on grid
• Error information: according to quality criterion,
~10 mGal (land), ~4-5 mGal (ocean)
-40
-60
ESA Living Planet Symposium 2013,
Edinburgh, September 09-13 2013
Results
Output field [mGal]
Error estimates [mGal]
• Larger errors
where only
satellite data
available (mainly
omission part!!!)
• Realistic error
estimates.
ESA Living Planet Symposium 2013,
Edinburgh, September 09-13 2013
Restore & Validation with EGM2008
Restore (GOCO d/o 100 + topo-iso)  IMOSAGA01C
Free-air anomalies
Bouguer anomalies
IMOSAGA01C EGM2008
IMOSAGA01C EGM2008
difference
mGal
ESA Living Planet Symposium 2013,
Edinburgh, September 09-13 2013
Restore & Validation with EGM2008
Restore (GOCO d/o 100 + topo-iso)  IMOSAGA01C
Error estimates [mGal]
terrestr. input
difference
• Improved long-wavelength behaviour
• Large differences in regions without
terrestrial gravity
• Geophysical interpretation (Kiel) 
IMOSAGA01C makes more sense
mGal
ESA Living Planet Symposium 2013,
Edinburgh, September 09-13 2013
Lithospheric model (IGMAS+) - Iquique
• Iquique: terrestrial gravity available
Free-air anomalies
Bouguer anomalies
IMOSAGA01C EGM2008
IMOSAGA01C EGM2008
difference
mGal
ESA Living Planet Symposium 2013,
Edinburgh, September 09-13 2013
Lithospheric model (IGMAS+) - Iquique
• Only small variations compared to EGM2008
• Lithospheric model could be confirmed
ESA Living Planet Symposium 2013,
Edinburgh, September 09-13 2013
Lithospheric model (IGMAS+) - Beule
• Beule: low-quality terrestrial gravity data
Free-air anomalies
Bouguer anomalies
IMOSAGA01C EGM2008
IMOSAGA01C EGM2008
difference
mGal
ESA Living Planet Symposium 2013,
Edinburgh, September 09-13 2013
Lithospheric model (IGMAS+) - Beule
• Significant deviation to EGM2008
• Updated lithospheric model required (currently done)
ESA Living Planet Symposium 2013,
Edinburgh, September 09-13 2013
Lithospheric modelling
• In many regions due to lack of
terrestrial gravity data up to now no
lithospheric profile could be
modelled by IGMAS+.
• In these regions, now due to GOCE
data lithospheric modelling will
become possible for the first time!
ESA Living Planet Symposium 2013,
Edinburgh, September 09-13 2013
Summary and conclusions
Significant improvement of regional
gravity field models through combination
of terrestrial and satellite data
Main benefit in areas with terrestrial data gaps,
but also concerning the consistency in the long to
medium wavelengths
Proof of a clear impact of GOCE for lithospheric
modelling, especially in topographically challanging regions
Methodology also usable for validation of inhomogenous
gravity databases
Established processing procedure can be applied
worldwide (also with low-quality terrestrial data)
Updated lithospheric models will be available soon
ESA Living Planet Symposium 2013,
Edinburgh, September 09-13 2013
Final conclusion
ESA Living Planet Symposium 2013,
Edinburgh, September 09-13 2013

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