The Four Candidate Earth Explorer Core Missions consultative Workshop October 1999, Granada, Spain, Revised by CCT GOCE S 23 The gravity field reflects the anomalous density structures in the Earth’s interior in comparison to an idealized body in hydrostatic equilibrium. The geoid coincides with a hypothetical ocean surface at rest. All topography (on land, ice sheet and the ocean) is referred to it. Science and Application The dual role of the Earth’s gravity field

The Four Candidate Earth Explorer Core Missions consultative Workshop October 1999, Granada, Spain, Revised by CCT GOCE S 24 Science and Application The Gravity Field Mirror

The Four Candidate Earth Explorer Core Missions consultative Workshop October 1999, Granada, Spain, Revised by CCT GOCE S 25 Science and Application The Geoid Reference Surface

The Four Candidate Earth Explorer Core Missions consultative Workshop October 1999, Granada, Spain, Revised by CCT GOCE S 26 The GOCE derived gravity field with an accuracy of 1 mgal at a scale of 100 km will provide: new understanding of the physics of the Earth’s interior including geodynamics and anomalous density structure associated with the continental lithosphere, mantle composition and rheology and uplifting /subduction processes. Science and Application Solid Earth Physics

The Four Candidate Earth Explorer Core Missions consultative Workshop October 1999, Granada, Spain, Revised by CCT GOCE S 27 Science and Application Interior Structure and Geodynamic Processes

The Four Candidate Earth Explorer Core Missions consultative Workshop October 1999, Granada, Spain, Revised by CCT GOCE S 28 Science and Application Limitation of Seismic Data only

The Four Candidate Earth Explorer Core Missions consultative Workshop October 1999, Granada, Spain, Revised by CCT GOCE S 29 input data: 2D viscoelastic model (stress distribution) earthquake distribution seismic tomography petrological data model runs: run 1: convergence from model (no GOCE data) run 2: asthenospheric upwelling added (GOCE added) run 3: gravitational sinking of slab due to load (GOCE added) Science and Application Impact Study 1: Seismic Risk

The Four Candidate Earth Explorer Core Missions consultative Workshop October 1999, Granada, Spain, Revised by CCT GOCE S 30 Science and Application Impact Study 1: Seismic Risk (Tuscany) Study Area Model Setup

The Four Candidate Earth Explorer Core Missions consultative Workshop October 1999, Granada, Spain, Revised by CCT GOCE S 31 Science and Application Impact Study 1: Results Run 1 Run 2 Run 3

The Four Candidate Earth Explorer Core Missions consultative Workshop October 1999, Granada, Spain, Revised by CCT GOCE S 32 Inversion of gravity field data from GOCE will: impose constraint on interior density structure significantly improve understanding of processes controlling earthquake nucleation in seismic active regions Science and Application Impact Study 1: Conclusion

The Four Candidate Earth Explorer Core Missions consultative Workshop October 1999, Granada, Spain, Revised by CCT GOCE S 33 Science and Application Solid Earth Physics - Summary

The Four Candidate Earth Explorer Core Missions consultative Workshop October 1999, Granada, Spain, Revised by CCT GOCE S 34 The GOCE derived geoid with a 1 cm accuracy at a scale of 100 km will: meet an essential requirement for the determination, in combination with satellite altimetry, of the absolute ocean circulation and the associated transport of mass, heat and other properties Science and Application Oceanography

The Four Candidate Earth Explorer Core Missions consultative Workshop October 1999, Granada, Spain, Revised by CCT GOCE S 35 Science and Application Limitation of Altimetry

The Four Candidate Earth Explorer Core Missions consultative Workshop October 1999, Granada, Spain, Revised by CCT GOCE S 36 Science and Application Mean Dynamic Ocean Topography Below about 1000 km the Mean Dynamic Topography is poorly known

The Four Candidate Earth Explorer Core Missions consultative Workshop October 1999, Granada, Spain, Revised by CCT GOCE S 37 Science and Application Existing Geoid Knowledge Above degree (1000 km) the geoid error becomes dominant

The Four Candidate Earth Explorer Core Missions consultative Workshop October 1999, Granada, Spain, Revised by CCT GOCE S 38 Knowledge of this circulation is essential for: study of the impact of the shorter-scale ( km) mean flows on climate computation of heat and mass fluxes through basin-scale ocean sections study of non-linear oceanic dynamics and interdependence between the mean and variable parts of the flow Improved knowledge in these areas will advance the data assimilation schemes for ocean forecasting advance the Earth System Models for climate and sea level change studies Science and Application Absolute Ocean Circulation

The Four Candidate Earth Explorer Core Missions consultative Workshop October 1999, Granada, Spain, Revised by CCT GOCE S 39 Science and Application Impact Study 2: Mean Dynamic Topography Short spatial scales: - 1/12˚ MICOM ocean model of North Atlantic ocean topography simulated at wavelengths of < 1000 km, < 250 km and < 100 km - 1/8˚ OCCAM global model ocean topography simulated at wavelengths of < 1000 km and < 250 km