Langel R.A., Hinze W.J. The Magnetic Field of the Earth's Lithosphere: The Satellite Perspective

Cambridge University Press, 1998. — 446 p.Many geologic features of the earth's lithosphere create variations in the earth's magnetic field that can be detected by satellites. The resulting magnetic anomaly maps can provide new insights into the tectonic features and broad structures of the lithosphere. This book documents the acquisition, reduction, and analysis of satellite magnetic field data in the study of the earth's lithosphere. The isolation of the lithospheric field from fields originating in the earth's core, the ionosphere, and the magnetosphere is discussed in detail, and a summary of the characteristics of each field is included. This work also provides a complete summary of the published maps and the methods used to create them. Rock magnetism concepts and sources of variation in magnetization are discussed to help the reader understand the issues in interpreting the data, and the various interpretation methods, such as forward modeling, are summarized. Analysis results using data from North America, Africa, Australia, Europe, and the oceans illustrate the methodologies of interpretation and the anomalies associated with particular geologic and tectonic settings. Mapping and interpreting lithospheric fields from satellite magnetic data have required the solution of a new set of problems and the development of a new complement of analytic tools, resulting in a new subdiscipline of geomagnetism. Advanced students and researchers will find that The Magnetic Field of the Earth's Lithosphere provides a much needed review of this important topic.Preface page.
Lithospheric magnetic fields at satellite altitude.
Introduction.
Looking into the Earth's Interior.
Historical Development of Satellite Magnetic Anomaly Studies.
The Magnetic Field from the Lithosphere of the Earth.
Definitions and Relationships.
Magnetism of Rocks.
Introduction to Anomaly Maps.
General Characteristics of Satellite Data.
Earth's magnetic field.
Introduction.
The Field from the Earth's Core.
Spherical Harmonic Models.
Magnetic Coordinates.
Time Scales.
The Field from Sources External to the Earth.
The Magnetosphere.
Fields from the Ionosphere During Magnetic.
Quiet Conditions.
Temporal Magnetic Disturbances.
Magnetic Activity Indices.
The Measured Field at Satellite Altitude.
Measurement of the near-earth magnetic field from space.
Introduction to Satellite Data.
Magnetometers.
Error Sources.
Satellites Measuring the Near-Earth Magnetic Field.
Satellites Contributing to Lithospheric Magnetic Field Studies.
Data-Processing Issues.
Calibration of a Vector Magnetometer by a Scalar Magnetometer.
Determination of Spacecraft Field and Attitude Bias.
Dealing with Discontinuities in the Attitude Solution.
Isolation of anomaly fields.
Long-Wavelength Magnetic Anomalies.
Notation and Procedure.
Selection of Quiet Data.
Isolation from the Main Field.
Model Degree.
Main-Field Secular Variation.
Coordinate Systems.
Model Contamination by Ionospheric Fields.
Spherical Harmonic Degree and Wavelength.
Analysis of Long-Wavelength Trends.
Correction Function for Magnetospheric Fields.
Ad Hoc Trend Corrections.
High-Pass Filtering.
Crossover Analysis.
Polynomial Fit Along Orbital Tracks.
Wavelength Domain Estimation for the Common Signal in Multiple Sources.
Fourier Harmonic Correlation Analysis.
Spherical Harmonic Correlation Analysis.
Trade-Offs in the Correlation Analysis.
Spherical Harmonic Relationships.
Analytics of Lithospheric and Ionospheric Fields.
Introduction.
Estimation of the Coefficients.
Data from a Single Local Time.
Time Variations.
Summary and Discussion.
Models of the Equatorial Electrojet from Magsat Data.
A High-Latitude Disturbance Model.
Spherical Harmonic Models.
A Recommended Procedure.
Reduction and inversion.
Overview.
The Fundamental Inversion Problem.
The Magnetic Field of a Dipole.
Magnetization and Susceptibility.
The Equivalent Source Method, a Finite-Parameter Solution.
Reduction to Common Inclination (to the Pole) and Magnitude.
Uniqueness Considerations.
Basics of Estimation.
Overview.
Minimum-Variance Estimation with A Priori Information.
Local Models.
Spherical Cap Harmonic Analysis.
Rectangular Harmonic Analysis.
Gridding by Collocation.
Summary of Local Models.
Global Models.
Spherical Harmonic Potential.
Non-Potential Spherical Harmonic Representation.
Efficient Computation Techniques with Spherical Harmonics.
Equivalent Source Models.
Summary of Global Models.
Dealing with Instability: Principal-Component Analysis.
Causes and Examples of Instability.
Principal-Component Analysis.
Example from Equivalent Source Modeling.
Dealing with Instability: Minimum-Norm Solutions.
Minimum-Norm Concepts.
Ridge Regression.
Geomagnetic Norms.
Generalized Inverse Methods.
Minimum-Norm Magnetization.
An Estimate of the Potential Function and Susceptibility.
The Potential.
Susceptibility.
The Usefulness of Vector Data.
Summary.
Appendix.
Calculation of Derivatives of the Trace of Matrix Products.
Vector and Hilbert Spaces.
Calculation of Elements of the Gram Matrix A.
Anomaly maps.
Introduction.
Tabulation of Published Maps.
Scalar Maps at Low and Middle Latitudes.
Maps Based on Data from the POGO Satellites.
Maps Based on Data from Magsat.
Maps Based on Combined Magsat and POGO Data.
Vector Maps at Low and Middle Latitudes.
Maps of the Polar Regions.
Factors in High-Latitude Data.
North Polar Scalar Maps.
South Polar Scalar Maps.
Vector Maps.
Comparisons Between Maps.
A Correlation Procedure.
Correlative Intercomparison of Final Maps.
Comparisons of Satellite and Surface Surveys.
Problems with Intercomparing Surface and Satellite Surveys.
Published Comparisons.
Global Interpretive Maps.
Regional Maps.
General Comments.
Maps of Higher Resolution.
Summary and Recommendations.
Magnetic anomalies and their sources.
Introduction.
Sources of Magnetization Contrasts.
Fundamental Types of Magnetism.
Magnetic Minerals.
Magnetic Petrology.
Lithospheric Magnetization.
Continental Lithosphere.
Oceanic Lithosphere.
Summary.
Methods in interpretation.
Introduction.
Qualitative/Semi-Quantitative Methods.
Map Comparisons.
Application of Poisson's Theorem.
Quantitative Methods, Forward Modeling.
Introduction.
Flat-Earth Models.
A Spherical-Earth Model.
A Method for Specification of Magnetization Contrasts.
Typical Magnetic Anomalies.
Horizontal Resolution.
Resolution of Pairs of Magnetic Blocks in Satellite Scalar Magnetic Field Data.
Resolution of Magsat Data.
Global Magnetization with A Priori Information.
Discussion.
Global satellite magnetic anomaly interpretation.
Implications of the SEMM for Interpretation.
North America.
Overview.
Anomaly Studies.
Discussion.
Africa.
Overview.
Anomaly Studies.
Australia.
Europe.
Overview.
Anomaly Studies.
Oceans.
General.
Plateaus and Rises.
Summary.
Appendix.
References to Regional Studies.
Glossary of Symbols.
Common Abbreviations.
References.
Index.