Introduction to Geomagnetic Fields



With a profusion of excellent books on geomagnetism published or revised during the last few years (one, in fact, by the same publisher as Introduction to Geomagnetic Fields), we might ask why we need yet another on the same subject. I believe the answer is clear. This book fills a gap between the highly mathematical and technical coverage of G. Backus, R. Parker, and C. Constable's Foundations of Geomagnetism (1996) and the solid-Earth focus provided by R. T. Merrill, M. W. McElhinny, and P. L. McFadden's The Magnetic Field of the Earthsemi; Paleomagnetism, the Core, and the Deep Mantle (1996).

Perhaps Introduction to Geomagnetic Fields is best described by its first sentence: “This book is designed for those who want a condensed and less technical coverage of geomagnetic topics than is afforded by existing textbooks.” The foreword describes the book as a beginning textbook, containing minimal technical jargon without complex mathematical formulas. The author makes a valiant reach for this goal (becoming too elementary in some casessemi; we are provided, for example, with the definition of an arc tangent, a description of scientific notation, and a reminder that sin 90°=1) but is nly partially successful. By page 17, the book has already introduced Maxwell's and Laplace's equations in s pherical coordinates, complete with Legendre polynomials. This is certainly understandable (what could be more instructive than the single equation Δ 2V=0?), and the book does provide plenty of text to illustrate the physical meanings behind important formulations. The book has only five chapters covering the broad range of geomagnetic topics. The first chapter describes the Earth's main magnetic field, emphasizing its dipole and nondipole characteristics via spherical harmonic analysis. Geomagnetic components and charts are described, and there is a brief discussion of paleomagnetism and the fluid-core source of the internal field.