Synopses & Reviews
The ESA explorer core mission GOCE, to be launched in 2006, will enhance our knowledge of the global static gravity field and of the geoid by orders of magnitude. The U.S. satellite gravity mission GRACE (2002-2006) is currently measuring, in addition, the temporal variations of the gravity field. With these new data a whole range of fascinating new possibilities will be opened for solid Earth physics, oceanography, geodesy and sea-level research. The new generation of gravity missions employs sensor concepts for gravity field measurement, orbit and attitude control and orbit determination that show interesting similarities with space experiments planned in the field of fundamental physics. This volume is the result of a workshop that brought together some 50 acknowledged experts in their field to discuss (1) strategies for ultra precision orbit determination and gravity field modelling with the data of the upcoming gravity field missions, (2) the use of accurate and high resolution gravity models in Earth sciences whereby, in particular, synergy is expected between the various science fields in their use of this type of new information, and (3) gravity field requirements and possible sensor and mission concepts for the time after GRACE and GOCE.
Synopsis
This volume in the Space Sciences Series of ISSI is dedicated to the detennination of the Earth's gravity field, which was the topic of a workshop organized by ISSI from 11 to 15 March 2002 in Bern. The aim of the meeting was to gather active researchers from various fields (satellite geodesy, gravity field modelling, solid Earth physics, oceanography, etc.) to assess the exciting new developments that are made possible by space missions currently in orbit or about to be launched. Following some general enquiries with the scientific community concerning the desirability of organising a workshop on the proposed topic, a group of four con- venors (Gerhard Beutler, Univ. of Bern; Mark Drinkwater, ESA-ESTEC, Noord- wijk; Reiner Rummel, Techn. Univ. Miinchen; Rudolf von Steiger, ISS I, Bern) for- mulated the aims and goals of the workshop, structured the workshop into six sec- tions, nominated a list of session chairs (Georges Balmino, GRGS-CNES, Toulouse; Roberto Sabadini, Univ. of Milano, Christian Le Provost, Obs. Midi-Pyrenees, Toulouse; Philip Woodworth, Bidston Observatory, Birkenhead; Miguel Aguirre, ESA-ESTEC, Noordwijk), who in turn set up a programme of introductory talks. The workshop was organized such as to have only plenary sessions with typically half-hour presentations and ample time for discussions. The last day was devoted to conclusions and future objectives.
Table of Contents
Foreword. How to Climb the Gravity Wall;
R. Rummel. I: Precise Orbit Determination and Gravity Field Modelling. Strategies for Precise Orbit Determination of Low Earth Orbiters Using the GPS; U. Hugentobler, G. Beutler. Aiming at a 1 cm Orbit for Low Earth Orbiters: Reduced-Dynamic and Kinematic Precise Orbit Determination; P.N.A.M. Visser, J.van den IJssel. Space-Wise, Time-Wise, Torus and Rosborough Representations in Gravity Field Modelling; N. Sneeuw. Gravity Field Recovery from GRACE: Unique Aspects of the High Precision Inter-Satellite Data and Analysis Methods; G. Balmino. Global Gravity Field Recovery Using Solely GPS Tracking and Accelerometer Data from CHAMP; C. Reigber, et al. The Processing of Band-Limited Measurements: Filtering Techniques in the Least Squares Context and in the Presence of Data Gaps; W.-D. Schuh.
II: Solid Earth Physics. Long Wavelength Sea Level and Solis Surface Perturbations Driven by Polar Ice Mass Variations: Fingerprinting Greenland and Antarctic Ice Sheet Flux; M.E. Tamisiea, et al. Benefits from GOCE within Solid Earth Geophysics; A.M. Marotta. The Potential of GOCE in Constraining the Structure of the Crust and Lithosphere from Post-Glacial Rebound; L.L.A. Vermeersen. Deep and Shallow Solid-Earth Structures Reconstructed with Sequential Integrated Inversion (SII) of Seismic and Gravity Data; R. Tondi, et al. Present-Day Sea Level Change: Observations and Causes; A. Cazenave, et al.
III: Ocean Circulation. Global Ocean Data Assimilation and Geoid Measurements; C. Wunsch, D. Stammer. Resolution Needed for an Adequate Determination of the Mean Ocean Circulation from Altimetry and an Improved Geoid; C. Le Provost, M. Bremond. Error Characteristics Esimated from CHAMP, GRACE and GOCE Derived Geoids and from Satellite Altimetry Derived Mean Dynamic Topography; E.J.O. Schrama. Estimating the High-Resolution Mean Sea-Surface Velocity Field by Combined Use of Altimeter and Drifter Data for Geoid Model Improvement; S. Imawaki, et al. Combined Use of Altimetry and In Situ Gravity Data for Coastal Dynamics Studies; K. Haines, et al. Feasibility and Contribution to Ocean Circulation Studies of Ocean Bottom Pressure Determination; C.W. Hughes, V. Stepanov. Impact of Geoid Improvement on Ocean Mass and Heat Transport Estimates; P. Le Grand. How Operational Oceanography can Benefit from Dynamic Topography Esimates as Derived from Altimetry and Improved Geoid; P.Y. Le Traon, et al.
IV: Geodesy. Remarks on the Role of Height Datum in Altimetry-Gravity Boundary-Value Problems; F. Sacerdote, F. Sanso. Ocean Tides in GRACE Monthly Averaged Gravity Fields; P. Knudsen. Tidal Models in a New Era of Satellite Gravimetry; R.D. Ray, et al. The Elusive Stationary Geoid; M. Vermeer. Geodetic Methods for Calibration of GRACE and GOCE; J. Bouman, R. Koop.
V: Sea Level. Benefits of GRACE and GOCE to Sea Level Studies; P. Woodworth, J.M. Gregory. What Might GRACE Contribute to Studies of Post Glacial Rebound? J. Wahr, I. Velicogna. Measuring the Distribution of Ocean Mass Using GRACE; R.S. Nerem, et al. Monitoring Changes in Continental Water Storage with GRACE; S. Swenson, J. Wahr.
VI: Future Concepts. Attitude and Drag Control: An Application to the GOCE Satellite; E. Canuto, et al. On Superconductive Gravity Gradiometry in Space; S. Zarembinski. Satellite-Satellite Laser Links for Future Gravity Missions; P.L. Bender, et al. Possible Future Use of Laser Gravity Gradiometers; P.L. Bender, et al. MICROSCOPE Instrument Development Lessons for GOCE; P. Touboul. Needs and Tools for Future Gravity Measuring Missions; M. Aguirre-Martinez, N. Sneeuw.
VII: Closing Session. GOCE: First Earth Explorer Core Mission; M.R. Drinkwater, et al. Earth Gravity Field from Space From Sensors to Earth Sciences: Closing Remarks; G. Beutler. Author Index. List of Participants.