Geophysics yesterday and today

By Rachel Berkowitz

Last week San Francisco hosted the 2011 fall meeting of the American Geophysical Union (AGU). It is natural to expect that many of the 20 000 scientists from around the world who attended will submit their findings to AGU’s Journal of Geophysical Research (JGR). But who submitted the first JGR article ever published?

That honor belongs to Arthur Schuster of Owens College, a forebear of the University of Manchester in the UK. His was the first paper in the first issue of the first volume of JGR, then called Terrestrial Magnetism. The year was 1896.

Researchers who attended the 2011 AGU meeting have at their disposal satellite imaging and global information systems and decades of calculations and explanations of fundamental geophysical principles. But just over a century ago Schuster used only a barometer, some thermometers and anemometers, and Maxwell’s equations.

It makes one wonder what subjects that are new today will be taken for granted at an AGU meeting 115 years in the future.

Magnetic fields

JGR‘s inaugural article, ‘On electric currents induced by rotating magnets, and their application to some phenomena of terrestrial magnetism,’ explored how the behavior of the magnetic needle on the surface of Earth may provide information about whether interplanetary space is an electric conductor.

Schuster treated Earth as a magnetic sphere rotating in a conducting medium about an axis that does not coincide with its magnetic one. He asserted that a change in Earth’s magnetic axis would result and cause changes in the magnetic forces. The changes are identical to those observed in a compass needle.

But Earth is not a magnet. Rather, “convection in a [rotating] iron core is responsible for the magnetism that we see,” explains Kathy Whaler , a geophysicist at the University of Edinburgh. She adds that Schuster’s ideas have “gone out the window. [They] come down to exotic theories!”

Schuster may have gotten it wrong. But his efforts led Patrick Blackett to further investigate rotating bodies’ magnetism and develop a magnetometer to measure the strength of the magnetic field. Blackett’s instrument was a valuable addition to the toolbox for understanding how Earth works, although today’s detailed knowledge of Earth’s interior has come mostly from seismology.

New fields

Whether or not his geomagnetic theories were sound, Schuster helped found the discipline of atmospheric physics. He applied studies of harmonic analysis not only to variations in terrestrial magnetism but also to the upper atmosphere. He explored the equation of radiative transfer and how light is transmitted through fog. He set up a meteorology group within the physics department at Owens College, thus introducing meteorology as a university subject in the UK.

But a 1935 obituary for Schuster by G. C. Simpson, the first university lecturer in meteorology in the UK, notes that “it is a remarkable fact that Schuster never made any original contributions to the science of meteorology, yet it was a subject in which he was deeply interested and to which he devoted a great deal of his time and administrative ability.”

That assessment of someone who held leading roles in the meteorological organization of the Royal Society and the UK’s Meteorological Office is surprising.

David Schultz, who’s currently a meteorologist at the University of Manchester, acknowledges that in Schuster’s radiative transfer studies, “he was thinking of applying his knowledge of physics to the atmosphere.” Without an understanding of how radiation moves through and interacts with matter, weather forecasting and climate models would not be possible.

Geophysics tomorrow

I wish I could ask Schuster what ideas he thought people would be excited about at an AGU meeting a century later. I did pose the question to Schultz and Whaler.

Schultz thinks that “numerical weather prediction . . . which still depends on fundamental advances in data assimilation, numerical methods, and computing power, will be even better in 100 [years].”

Whaler is excited about new data from the three closely orbiting satellites that make up the European Space Agency’s Swarm mission, which is set for launch next year. Instruments aboard the satellites will produce what promises to be the highest-resolution map of the sources of Earth’s magnetic field.

Schuster certainly could not have seen where his first forays into atmospheric physics back in 1896 would lead. It will be interesting to see where the results and papers from this year’s fall AGU meeting take us.