GOCE Research in Germany: From Sensor Analysis to Earth System Science

Transcription

1 GOCE Research in Germany: From Sensor Analysis to Earth System Science Reiner Rummel, Jakob Flury and Thomas Gruber Institut für Astronomische und Physikalische Geodäsie Technische Universität München 3. International GOCE User Workshop ESA-ESRIN Frascati Rome November 2006

2 Contents: GOCE Science Objectives and Research Challenges GOCE-GRAND-2 second phase GOCE related research activities in Germany GOCE project office

3 GOCE Mission Objectives Acronym: Gravity and Steady-State Ocean Circulation Explorer Mission Objectives: Geoid std.dev. 1cm Gravity (anomalies) std. dev. 1mGal Spatial resolution: 100 km (Lmax= 200) Launch: September 2007

4 applications of static gravity field solid earth ocean ice geodesy sea level gravity anomalies seismic tomograpy geoid gravity anomalies geoid ocean altimetry ice topography positioning (GPS) tide gauges altimetry topography deformations laboratory mean ocean circulation bedrock topography levelled heights post glacial rebound unified height system mean ocean circulation anomalous density structure constraints on mass & heat transport mass balance of ice sheets gravity anomalies ice mass balance orbits unified height systems INS orbits

5 science requirements SOLID EARTH APPLICATION ACCURACY SPATIAL RESOLUTION Geoid (cm) Gravity (mgal) half wavelength - D (km) lithosphere / upper mantle density continental lithosphere sedimentary basins rifts tectonic motions seismic hazards ocean lithosphere / asthenosphere short scale OCEANOGRAPHY basin scale ~ rock basement ICE SHEETS ice vertical movements levelling by GPS unified height systems GEODESY INS ~ orbits ~ Many of the above applications, SEA LEVEL CHANGE with their specific requirements, are relevant to studies of sea level change Gravity Field and Steady-State Ocean Circulation Mission ESA, SP-1233 (1), 1999, p.80

6 GOCE and steady-state ocean circulation requires two surfaces and therefore two satellite sensor systems to be globally consistent at the cm-level satellite altimetry GOCE

7 GRACE: maximum precision (geoid <!m) GOCE: maximum resolution (s= 80 km)

8 error Power Density Spectrum for {zz}-component noise filter MBW

9 GOCE High Level Processing Facility GOCE Standards Doc. No.: GO-TN-HPF-GS-00xx Issue: 1 Revision: 0 Date: October / 2006 Prepared by: The European GOCE Gravity Consortium EGG-C

10 GOCE gravity model: global spherical harmonic series terrestrial gravity data: regional pointwise, block averages

11 Calibration and Validation GOCE CAL/VAL data sets spatial represention global regional local spatial represention global regional local long wavelength short spectral representation long wavelength short spectral representation

12 Calibration and Validation GOCE CAL/VAL data sets spatial represention global regional local spatial represention global regional local long wavelength short spectral representation long wavelength short spectral representation

13 Regional Validation and Combination Experiment Observations of vertical deflections (courtesy IFE Hannover)

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15 A Selection of Research Challenges: take into account pecularities of sensor system get lowest harmonics right get altimetry and GOCE into one consistent reference system ensure definition and implementation of adequate standards revisit theory of geodetic boundary value problem work on optimal combination of geopotential models and on their combination with terrestiral data develop appropriate validation methods and experiments

16 GOCE related activities in Germany Participation in ESA GOCE processing (ESA contracts): PDS, HPF, CMF, CAL/VAL, GUTs, studies Connection to GT Theme 2 Observation of Earth System from Space Participation in DFG Priority Programme 1257 Mass Transport and Mass Distribution in System Earth Involvement in IAG Pilot Project: GGOS (will belong to IGOS and GEO)

17 GOCE-Grand 2 Financed by German Research Ministry through GeoTechnologyProgramme its Theme 2 Observation of Earth System from Space U Bonn U Hamburg U Hannover BKG Frankfurt U Stuttgart GFZ Potsdam TU München

18 GOCE Gravity Field Processing Adaptive Refinements in GOCE Gravity Field Modelling and Implementation of the Operational Software pcgma GOCE Gravity Field Modelling Further Methodology Investigation on Alternative Estimation Procedures SST and SGG Gravity Analysis Realization of the Actual GOCE Sensor Concept The Polar Gap Problem Solution Strategies and Influence on the GOCE/GRACE Combination Solution Regionally Adapted Global Gravity Field Determination by SGG and SST Data Results of GOCE-GRAND I Combined Gravity Modelling Calibration and Validation High Resolution Global Combination Solutions Quality Assessment of GOCE Gradients Gravity Field Validation with Terrestrial Geoid and Gravity Anomalies Regional Validation and Combination Experiment Gravity Field Validation Using Ocean Data and Ocean Dynamics Integral Motion and its Role for Consistency Validation of Force Functions and Orbits Other Geotechnology II Projects: Optimized GRACE Level-1 and Level-2 Products More Precise and Faster Gravity Field Products (CHAMP,GRACE) IAPG ITG GFZ GIS BKG & IFE IFE IFM

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20 GOCE-GRAND-2 Working Groups GOCE Standards System Transformations; Geometrical Models; Dynamical Models. GOCE and Surface Data GOCE and Applications Combination & Validation; Corrections to be applied; Data Weighting; Aliasing & Filtering Techniques. Identification of Needs; Reference Potential W 0 ; Derived Gravity Field Quantities on Ellipsoid or Earth Surface.

21 Proposal to German Research Foundation (DFG) coordinator: : K-H Ilk granted: : 2005

22 Mass Transport in the Earth System gravity field missions ocean transport (mass/heat) ocean surface circulation (altimetry - geoid) deep ocean circulation (bottom pressure) sea level mass vs. volume change (altimetry / gravity) atmosphere CHAMP GRACE GOCE altimetry missions Envisat CryoSat Jason-1 ICESat complementary remote sensing TerraSAR, topography, sea surface temperature, winds, salinity, soil moisture (SMOS) etc. from satellite sensor data to mass signals combination of geometry and gravity in space and time in one reference system, data preparation for model assimilation, terrestrial/ airborne data, separation of signal effects, complementary data hydrological cycle continental water budget, closure of global and regional water balance, water storage variation, trends and climate change ice mass balance and sea level ice surface: height change, velocities, mass budget of ice sheets, bottom topography, sea level rise from melting, dynamic ice models, sea ice: coverage, thickness dynamics of mantle and crust mantle dynamics and geoid signal, geoid time variation from glacial isostatic adjustment, plumes, slabs, gravity signal of crustal and lithosphere structure

23 IAG Pilot Project: Global Geodetic Observing System

24 Coordination of GOCE activities by GOCE project office financed by DLR (German Aerospace Center) responsible for: activation of user community coordination of GOCE activities public relations contact with industry and funding agencies

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29 GGOS: Geodesy and System Earth Gravity field missions and variations in l.o.d. CHAMP GRACE GOCE Altimetry missions Geometry 3D+T: shape of Envisat land surfaces Jason-1 ice shields oceans ICESat Earth Rotation Precession/ nutation polar motion CryoSat Oceanic transport ocean circulation (quasi-static and time v ariation), mass and heat transport, eddies, sea lev el: mass and v olume change From satellite space sensor and terrestrial data to Geodetic Earth data system to Earth consistent System combination Parameters of Space geodetic data, reference sy stems, Consistent models data preparation for model assimilation, Separation of effects regional representation, filtering, error models, Data separation processing of signal Data components, combination mass balance, filtering complementary data Continental hydrology Continental w ater budget, closure of w ater balance (global, regional) w ater storage v ariation, trends and climate change Atmosphere and Ionosphere Composition of ionoshere Atmospheric sounding (T,H, P) Tropospheric models Mass balance atmosphere Ice mass balance and sea level ice surface: height change, v elocities, mass budget of ice sheets, sea lev el rise from melting, dy namic ice models, sea ice: cov erage, thickness Complementary remote sensing TerraSAR (2005) Gravity/ Geoid Topography 3D+T: detailed Sea temperature geoid Wind, Salinity, and gravity anomaly field Soil moisture, SMOS, etc Dynamics of mantle and crust mantle dy namics and geoid signal, time v ariation from global isostatic adjustment, plumes, slabs, grav ity signal of crustal and lithospherie structures Earth Deep Interior Core-Mantle Coupling Mantle anelasticity ICB flattening (after Ilk KH et al., 2005) From Earth to Planets Moments of Inertia Fluid core? Isostatic (un)equilibrium Shape and gravity field

30 GOCE ground segment level 0 GOCE Cal/Val Team CMF PDS HPF GOCE-GRAND-2 GOCE User Toolbox ILRS IGS ECMWF level 1a/1b level 2 GOCE Application Studies GOCE Users level 3

31 GOCE ground segment level 0 CMF PDS ILRS IGS level 1a/1b ECMWF GOCE Cal/Val Team HPF level 2 GOCE User Toolbox GOCE Application Studies GOCE Users level 3

32 Users (Science and Application) solid Earth physics physical oceanography and climate research geodesy sea level research

33 Sensor Measurements Gravity gradients " xx, " yy, " zz in instrument system and inside MBW (measurement bandwidth) 3-axis gravity gradiometer Angular accelerations (highly accurate around y-axis, less accurate around x, z axes) Common mode accelerations Star sensors GPS receiver Drag control with 2 ion thrusters Angular control with magnetic torquers Orbit altitude maintenance Internal calibration of gradiometer (and quadratic factors) High rate and high precision inertial orientation Orbit trajectory with cm-precision Based on common mode accelerations from gradiometer data Based on angular rates from star sensors and gradiometer Based on GPS orbit Random shaking with cold gas thrusters (and random pulses)

34 Status of GOCE development newly developed GPS receiver laser tracking

35 Status of GOCE development Attitude and Drag-free control

36 accelerometers, 1-axis gradiometer 3-axis gradiometer Status of GOCE development

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39 GRACE: maximum precision (geoid <!m) GOCE: maximum resolution (s= 80 km)

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41 Klassische Bilanzgleichungen Impulsbilanz Drehimpulsbilanz Energiebilanz MR&! K = 0 MR&! K = 0 MR&! K = 0 vektorielle Multiplikation mit R skalare. Multiplikation mit R MR " R&! R " K = 0 M& R " R&! K " R& = 0 Zeitintegration Zeitintegration Zeitintegration t M R &! " Kdt = P t 0 0 t M R! R& " # R! Kdt = L t MR & 2 t " # K! R& dt = E t 0 Impuls = Anfangsimpuls + integrierte Kraft Drehimpuls = Anfangsdrehimpuls + integriertes Drehmoment Energie = kinetische Energie - integrierte Arbeit

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46 Mass Transport in the Earth System gravity field missions ocean transport (mass/heat) ocean surface circulation (altimetry - geoid) deep ocean circulation (bottom pressure) sea level mass vs. volume change (altimetry / gravity) atmosphere CHAMP GRACE GOCE altimetry missions Envisat CryoSat Jason-1 ICESat complementary remote sensing TerraSAR, topography, sea surface temperature, winds, salinity, soil moisture (SMOS) etc. from satellite sensor data to mass signals combination of geometry and gravity in space and time in one reference system, data preparation for model assimilation, terrestrial/ airborne data, separation of signal effects, complementary data hydrological cycle continental water budget, closure of global and regional water balance, water storage variation, trends and climate change ice mass balance and sea level ice surface: height change, velocities, mass budget of ice sheets, bottom topography, sea level rise from melting, dynamic ice models, sea ice: coverage, thickness dynamics of mantle and crust mantle dynamics and geoid signal, geoid time variation from glacial isostatic adjustment, plumes, slabs, gravity signal of crustal and lithosphere structure

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49 GOCE design elements: GOCE design elements: 3-axis gravity gradiometer GPS (orbit + low harmonics) star sensor (orientation in space) active attitude control (magnetic torquers) active drag compensation (along-track) stable and rigid material x now: magnetic torquers

50 Instrument Concept translational forces angular forces GPS/GLONASS SST -hl star sensors * * A B GRAVITY GRADIOMETER measures: gravity gradients angular accelerations common mode acc. drag control angular control

51 unified height systems sea surface topography ocean mass transport sea level changes glacial isostatic adjustment earthquakes slow component bathymetry continental lithosphere

52 GOCE Mission Characteristics: orbit altitude: 250 km inclination: one orbit cycle:! 30 to 40 days mission duration: gradiometer: orbit: launcher: 20 months 3 me/"hz 1-3 cm Rockot class

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54 Electrostatic Gravity Gradiometer

55 GOCE ground segment CMF PDS HPF ILRS IGS ECMWF

56 Auslenkung der tatsächlichen Meeresoberfläche (gemessen mit Satellitenaltimetie) bezüglich der Niveaufläche auf Meeresniveau, dem Geoid (berechnet aus Schwerefeldmodell) = dynamische Meerestopographie