GOCE EXPLOITATION FOR MOHO MODELING AND APPLICATIONS D. Sampietro

Transcription

1 ci_net 011 workshop GOCE EXPLOITATION FOR MOHO MODELING AND APPLICATION D. ampietro Department of Hydraulic, Environmental, Infrastructure and urveying Engineering The present research has been partially funded by EA through the GEMMA project.

2 PROBLEM TATEMENT AND CIENTIFIC CHALLENGE The Moho is a physical discontinuity between the Earth crust and the upper part of the mantle separating rocks with different densities. Moho estimation is traditionally based on: - seismic data (profiles) - ground gravity data (points) Andrija Mohorovičić ci_net 011 workshop

3 PROBLEM TATEMENT AND CIENTIFIC CHALLENGE Data from 1950 to nowdays; CRUT.0 Bassin et Al., 000 Older profiles were digitized by hand from published papers; For some areas regional Moho depth maps, compiled using deep seismic data have been used; In large areas of outh America, Africa, Antartica and part of the Ocean models are based only on few and poor quality data; from Tsoulis, 004 ci_net 011 workshop

4 PROBLEM TATEMENT AND CIENTIFIC CHALLENGE The GOCE mission is observing the Earth s gravitational field with unprecedented accuracy and resolution. The solution of inverse gravimetric problems can benefit from GOCE. The GOCE mission can be used to improve the existing model or to estimate the Moho in large areas from a homogeneous dataset. The main objective of the GOCE EXPLOITATION FOR MOHO MODELING AND APPLICATION (GEMMA) project is to improve the knowledge of the crust-mantle discontinuity surface by using data coming from satellite mission. ci_net 011 workshop

5 AREA OF TUDY 1. Improvement of a global reference Earth Moho Model A model with only the low frequencies, based on very simply approximations to be used as a-priori information for local moho studies.. Local studies in critical regions such as: ci_net 011 workshop

6 DATA ET GOCE data (potential and second radial derivative) on a grid at satellite altitude with stationary noise. Observations used: gridded values of - Potential - econd radial derivatives ci_net 011 workshop

7 DATA ET Geological information (where available) to constrain the model e.g.: - Local sediment models; - Local crust density models ; - eismic profiles; - Ground gravity anomalies We do not know the error structure of these data. ci_net 011 workshop

8 THE PROPOED APPROACH: HYPOTHEE To guarantee the uniqueness of the solution for the inverse gravimetric problem some simplifying hypotheses are required. Hypotheses two-layer model: 1) from topography to Moho ) from Moho to the bottom of the lithosphere Problems: Regularity of the Moho Effect of anomalous masses ci_net 011 workshop

9 METHODOLOGY (GLOBAL MODEL) Global models of the Earth gravitational potential are typically expressed as a spherical harmonic expansion: V ( r,, ) GM R L 0 m0 R r 1 V m Y m (, ) spherical harmonics of degree and order m Gravitational potential coefficients 10, m 0 10, m 10, m 5 ci_net 011 workshop

10 METHODOLOGY (GLOBAL MODEL) GOCE OBERVATION DATA REDUCTION PHERICAL HARMONIC ANALYI V ( r,, ) GM R L 0 m0 R r 1 V m Y m (, ) ediments do not look significant at global scale. LINEARIZED RELATION BETWEEN GRAVITATIONAL POTENTIAL COEFFICIENT AND MOHO COEFFICIENT L M (, ) M Y (, ) 0 m0 m m PHERICAL HARMONIC YNTHEI GLOBAL MOHO ci_net 011 workshop

11 PRELIMINARY REULT (GLOBAL MODEL) A GOCE only global Moho model, based on very simple hypotheses, to be used as preliminar model for local studies. Hypotheses - Reduction only for topography - Constant density contrast - GO_CON_GFC PW_R model - Mean Moho depth from CRUT.0 ci_net 011 workshop

12 PRELIMINARY REULT (GLOBAL MODEL) Improvement of the CRUT.0 global Moho model. Empirical error maps Original and corrected models The gravitational signal generated from the updated model is consistent with the actual gravitational field observed by GOCE. ci_net 011 workshop

13 T(x) Tzz(x) z Observables T T METHODOLOGY (LOCAL MODEL) dd DD h x G Linearization Fourier Transform d hdd G dd d h x z x Tx Tx k x D zz T d x T x Tzzx k x D zz Convolutions T zz d z0 Error spectra T,Tzz Dˆ zz zz (f ) Wiener filter prediction T,Tzz zz f Tˆ 0 Tˆ zz0 kˆ Tzz kˆ D zz kˆ zz Inverse Fourier Transform kˆ T D kˆ D Tzz T zz D kˆ kˆ T T D zz T zz D kˆ D D T zz D zz Tˆ Tˆ f kˆ f Dˆ f ˆ f 0 T zz0 f kˆ f Dˆ f ˆ f Tzz zz Moho Error covariance ci_net 011 workshop

14 PRELIMINARY REULT (LOCAL MODEL) THE GOCE ETIMATED MOHO BENEATH THE TIBETAN PLATEAU AND HIMALAYA General good agreement between GOCE Moho model and seismic profiles at low frequencies. Discrepancies between GOCE model and seismic profiles can be used to detect anomalies into the Moho. moothing effect due to the presence of a very deep Moho with high variability. Better results are expected in other regions of the world. ci_net 011 workshop

15 PRELIMINARY REULT (LOCAL MODEL) PROFILE (WET-EAT) Very large differences (about 10km) between 300 and 450 km in corrispondence of the collision between Indian and Eurasian plates. DICREPANCIE BETWEEN GOCE AND EIMIC CAN BE UED TO DETECT ANOMALIE INTO THE MOHO GOCE-only Moho GOCE + eimic profiles Moho ci_net 011 workshop

16 PRELIMINARY REULT (LOCAL MODEL) TIBETAN PLATEAU AND HIMALAYA ITALY PARANÀ BAIN ci_net 011 workshop

17 REULT 1) AN INVERE GRAVIMETRIC PROBLEM WITH GOCE DATA. M. Reguzzoni, D. ampietro International Association of Geodesy ymposia, Gravity, Geoid and Earth Observation, IAG Commission : Gravity Field (oral presentation and contribute published in the proceedings); ) MOHO ETIMATION UING GOCE DATA: A NUMERICAL IMULATION. M. Reguzzoni, D. ampietro, (in print). Presented to Geodesy for Planet Earth, 31 August 4 eptember 009, Buenos Aires, Argentina (oral presentation and contribute published in the proceedings); 3) UNIQUENE THEOREM FOR INVERE GRAVIMETRIC PROBLEM. D. ampietro and F. ansó, (in print). Presented to VII Hotine- Marussi ymposium. Rome, 6-10 June, 009 (poster presentation and contribute published in the proceedings) 4) A TUDY ON THE AUTRIAN MOHO FROM GOCE DATA; M. Reguzzoni, D. ampietro EGU General Assembly 011,Vienna (poster presentation); 5) GOCE EXPLOITATION FOR MOHO MODELING AND APPLICATION; D. ampietro, 4th International GOCE User Workshops, Munich. Proceedings of the 4th GOCE user workshop, 31 March 1 April 011, Technische Universitat Munchen (TUM), Germany (oral presentation and contribute published in the proceedings); 6) THE GOCE ETIMATED MOHO BENEATH THE TIBETAN PLATEAU AND HIMALAYA; D. ampietro, M. Reguzzoni, C. Braitenberg XXV IUGG General Assembly 011, Melbourne. (oral presentation and contribute published in the proceedings); 7) GLOBAL MOHO ETIMATE FROM GOCE PACE-WIE OLUTION AND A LOCAL APPLICATION IN THE MEDITERRANEAN AREA; D. ampietro, R. Barzaghi, A. Borghi, M. Reguzzoni AGU Fall meeting 011 (accepted as oral presentation). 8)GLOBAL MOHO FROM THE COMBINATION OF THE CRUT.0 MODEL AND GOCE DATA. D. ampietro, M. Reguzzoni GNGT 011, (oral presentation and contribute published in the proceedings); elected for the AGLC prize ci_net 011 workshop

18 REULT - Presentation of the project - Downloadable material - Global and local Moho models (asci grid) - presentations, posters, etc ci_net 011 workshop

19 CONCLUION A method to locally model the Moho discontinuity, based on collocation and FFT, has been implemented; The method has been applied to estimate local Moho models in the Tibetan region, Italy and Paranà basin (south America) giving good results; Discrepancies between GOCE model and seismic profiles can be used to detect anomalies into the Moho; A reference GOCE-only global Moho model with a resolution of 1 x1 has been computed; A correction to the CRUT.0 model has been computed from GOCE data; Estimation error is available for all the computed models; ci_net 011 workshop

20 FUTURE WORK The GEMMA project has been funded by EA and Politecnico di Milano and has a duration of years. WP0000 Project management WP1000 GENERALIZATION OF THE PROPOE APPROACH TO PHERICAL APPROXIMATION. WP000 AEMENT OF THE COVARIANCE FUNCTION AND OF THE ETIMATION ERROR. WP3000 ICE HEET ETIMATION IOLATION OF THE GRAVIMETRIC IGNAL WP4000 ON-LINE OFTWARE AND MAP GENERATION WP5000 ci_net 011 workshop