Robert L. Parker

2008 John Adam Fleming Medal Winner

Robert L. Parker was awarded the 2008 John Adam Fleming Medal at the AGU Fall Meeting Honors Ceremony, held 17 December 2008 in San Francisco, Calif. The medal is for “original research and technical leadership in geomagnetism, atmospheric electricity, aeronomy, space physics, and related sciences.”


This year’s AGU John Adam Fleming medalist, Robert Parker, is a unique individual. He possesses not only enormous mathematical flair and an inquiring mind but also a passion for passing his knowledge and his enthusiasm on to generations of students who have benefited from his tutelage. His research accomplishments range across the entire spectrum of geomagnetism. His elegant and long-standing work in electromagnetic induction and resistivity sounding alone is worthy of the award, and yet Bob has made crucial contributions within the areas of seamount magnetism; statistical models of paleosecular variation; numerical methods for potential field modeling applied to the crust and core; and rigorous theories for extremal inversions for magnetization structure on Earth and on Mars. He is a world-renowned expert on the general subject of inverse theory, having written one of the authoritative books on the subject.

Rigorous interpretation of a set of geophysical data is a passion for Bob Parker. This is borne out no more so than in his work on the inverse problem of electromagnetic induction. This nonlinear problem has a remarkable solution that Bob probably regards as his most important research contribution. Bob’s development of the solution to the inverse problem generated three seminal papers published in the early 1980s showing the form of the best fitting conductivity model for a set of data. A crucial outcome of this work was a definite statement about the maximum depth for which electrical conductivity properties could be derived from a certain data set. Parker’s work on this problem continues to the present day, and his most recent contribution with student Ashley Medin and colleague Steve Constable shows the confidence limits that can be placed on water in the upper mantle.

In the area of main field geomagnetic modeling, Bob Parker was responsible for a paradigm shift in the treatment of the inverse problem of determining the global geomagnetic field. Working with his student Loren Shure and longtime colleague George Backus, his idea of smoothing or regularizing the field at the core-mantle boundary rather than other schemes, termed the method of harmonic splines, has led to discoveries concerning the magnetic field in the core that could never have taken place otherwise. In the area of modeling of magnetic fields and magnetization of surface rocks Bob Parker has made numerous important contributions. He seized the opportunities arising with the advent of new data over seamounts to attack the inverse problem of seamount magnetism. Bob Parker developed the theory of ideal bodies in both gravity and magnetism, and applied the latter to derive bounds on the magnetization on Mars. In paleomagnetism the statistical model of paleosecular variation of Constable and Parker remains a touchstone for paleomagnetism, by virtue of its simplicity. Bob Parker’s well-known book on inverse theory has proved to be an inspiration for many of us, owing to its pedagogical explanations of the intricacies of the subject. Parker has also coauthored the authoritative book Foundations of Geomagnetism.

—ANDREW JACKSON, Institut für Geophysik, ETH Zürich, Zürich, Switzerland


Thank you, Andy, for your generous assessment of my work. It is truly an honor to be awarded this prestigious medal and to join the ranks of my illustrious predecessors.

If there is a theme in the list of apparently random things I’ve worked on that Andy has told you about, it is my interest in trying to understand what it is one can deduce from a geophysical data set with utmost confidence. I have been profoundly influenced in this quest by my friend and colleague George Backus, also a Fleming medalist. He once drew a conclusion based on the assumption that the energy stored in the geomagnetic field was probably less than mc2, where m is the Earth’s mass; only George would say, “probably.”

I was attracted to inverse problems in gravity, magnetism, and electromagnetism precisely because they seem to present a much more fuzzy view of the interior than seismology, where things are so beautifully clear, or at least they are alleged to be. A magnetic survey obviously must contain some information, but what is it exactly, given that such a wide variety of models can match observation? A common solution is to pile on as many assumptions as necessary to get a unique answer. But then how much of that answer comes from preconception? My preference is to make as few assumptions as possible and to explore the complete range of alternatives. The downside of my alternative is the risk that when you get your answer, everyone says, “We knew that already.” In fact, everybody didn’t really know it; they just believed it, and there is a difference between knowledge and belief.

I have been incredibly lucky to have worked with some very talented students. I would like to mention a few. Marcia McNutt, president and CEO of the Monterey Bay Aquarium and Research Institute, and former president of AGU, was my student, as was Cathy Constable, who is now my colleague at the Institute of Geophysics and Planetary Physics, and now president of AGU’s Geomagnetism and Paleomagnetism section. Philip Stark, now a distinguished professor of statistics at the University of California, Berkeley, was my most mathematical and skeptical student; he earned his bachelor’s degree in philosophy.

Another former student is Loren Shure, employee number 2 at the MathWorks, which created MATLAB. Loren and I wrote a program called plotxy with Alan Chave, which inspired parts of MATLAB. I enjoy writing general-purpose computer programs, but it is the fate of software written by people like me to be overtaken by the work of the professionals, like Loren and my son Paul, who works for Google, by the way.

There are really two aspects of science: the narrative and the technical. The narrative side is the one that gets the public’s attention: meteorite wipes out the dinosaurs; water discovered on Mars; Earth’s magnetic dipole heading toward zero in the near future. But while we all love a good story, it is the quality of the technical support for the story that distinguishes the good science from the bad, separates real neuroscience from Freud. So I am particularly proud to have been awarded AGU’s John Adam Fleming Medal, which explicitly recognizes technical accomplishments.

—ROBERT L. PARKER, University of California, San Diego