The Analysis Of The Earths Gravity Field

Volume resulting from an ISSI Workshop, 11-15 March 2002, Bern, Switzerland

Introduction.- Part I: Forward Modelling of the Gravity Field.- The Vertical Gravitational Signal of Homogeneous Bodies, Bounded in the Horizon Plane.- Fourier Methods.- Part II: The Preprocessing and Processing of Gravity Data: From Observations to a Gravity Map on a Local Horizontal Plane.- The Gravity Field of Earth.- Gravity Surveying and Preprocessing.- Gravity Processing.- Part III: Inverse Theory and Applications.- Elementary Inverse Theory.- On the Mathematical Characterization of the Inverse Gravity Problem.- General Inversion Approaches.- Some Conclusions.- Part IV: Appendices.- Mathematical Auxillia.- The Theory of Random Fields and the Wiener-Kolmogorov Prediction Method.- The Tikhonov Regularization and Morozov's Discrepancy Principle.

This book offers extensive information on the operation of gravimeters, including airborne, marine and terrestrial ones, and on the associated data processing methods such as optimal and adaptive filtering, smoothing, structural and parametric identification. Further, it describes specific features relating to the study of the gravitational field in remote areas of the Earth, with the necessary modifications of equipment and software for all-latitude applications. Findings from gravity studies in such remote areas are also presented. Advanced methods for studying the gravitational field, including those for simultaneous determination of gravity anomalies and deflection of the vertical are described and analyzed in detail. Gravity gradiometers and cold atom gravimeters are also covered. Last but not least, the book deals with the development of Earth’s gravity field models and their various applications, including map-aided navigation, with a special attention to model accuracy estimation. Gathering research findings and best practice recommendations relating to Earth’s gravity field measurements, collected by a team of researchers and professionals, the book offers a unique guide for engineers, scientists and graduate students dealing with terrestrial, marine and airborne gravimetry. It will also help other specialists involved in developing and using navigation systems in practice, including designers of gravimetric equipment and navigators.

This book provides a sound theoretical basis for the the different gravity field recovery methods and the numerics of satellite-to-satellite tracking data. It represents lectures given at the ‘Wilhelm and Else Heraeus Autumn School’ in Bad Honnef, Germany, October 4-9, 2015. The emphasis of the school was on providing a sound theoretical basis for the different gravity field recovery methods and the numerics of data analysis. The approaches covered here are the variational equations (classical approach), the acceleration approach and the energy balance approach, all of which are used for global gravity field recovery on the basis of satellite observations. The theory of parameter estimation in satellite gravimetry and concepts for orbit determination are also included. The book guides readers through a broad range of topics in satellite gravimetry, supplemented by the necessary theoretical background and numerical examples. While it provides a comprehensive overview for those readers who are already familiar with satellite gravity data processing, it also offers an essential reference guide for graduate and undergraduate students interested in this field.

For the past three decades, it has been possible to measure the earth's static gravity from satellites. Such measurements have been used to address many important scientific problems, including the earth's internal structure, and geologically slow processes like mantle convection. In principle, it is possible to resolve the time-varying component of the gravity field by improving the accuracy of satellite gravity measurements. These temporal variations are caused by dynamic processes that change the mass distribution in the earth, oceans, and atmosphere. Acquisition of improved time-varying gravity data would open a new class of important scientific problems to analysis, including crustal motions associated with earthquakes and changes in groundwater levels, ice dynamics, sea-level changes, and atmospheric and oceanic circulation patterns. This book evaluates the potential for using satellite technologies to measure the time-varying component of the gravity field and assess the utility of these data for addressing problems of interest to the earth sciences, natural hazards, and resource communities.

Advances in space-borne technologies lead to improvements in observations and have a notable impact on geodesy and its applications. As a consequence of these improvements in data accuracies, spatial and temporal resolutions, as well as the developments in the methodologies, more detailed analyses of the Earth and a deeper understanding of its state and dynamic processes are possible today. From this perspective, this book is a collection of the selected reviews and case-study articles that report the advances in methodology and applications in geodesy. The chapters in the book are mainly dedicated to the Earth’s gravity field theory and applications, sea level monitoring and analysis, navigation satellite systems data and applications, and monitoring networks for tectonic deformations. This collection is a current state analysis of the geodetic research in theory and applications in today’s modern world.

The author of this history of mankind’s increasingly successful attempts to understand, to measure and to map the Earth’s gravity field (commonly known as ‘little g’ or just ‘g’) has been following in the footsteps of the pioneers, intermittently and with a variety of objectives, for more than fifty years. It is a story that begins with Galileo’s early experiments with pendulums and falling bodies, progresses through the conflicts between Hooke and Newton and culminates in the measurements that are now being made from aircraft and satellites. The spectacular increases in accuracy that have been achieved during this period provide the context, but the main focus is on the people, many of whom were notable eccentrics. Also covered are the reasons WHY these people thought their measurements would be useful, with emphasis in the later chapters on the place of ‘g’ in today’s applied geology, and on the ways in which it is providing new and spectacular visions of our planet. It is also, in part, a personal memoir that explores the parallels between the way fieldwork is being done now and the difficulties that accompanied its execution in the past. Selected topics in the mathematics of ‘g’ are discussed in a series of short Codas.