The explosion of an underground nuclear device by North Korea this week disturbed the Earth’s ionosphere. The blast generated infrasonic waves that propagated all the way to the upper atmosphere causing small variations in the density of electrons there.
By analyzing the signals from GPS satellites collected at ground-based monitoring stations in South Korea and Japan, scientists at the California Institute of Technology’s Jet Propulsion Laboratory, Purdue University, and the Korea Advanced Institute of Science and Technology independently confirmed the ionospheric disturbance generated by the North Korean test.
The researchers used the same GPS signals that are used by surveyors for precise positioning. These signals are slightly perturbed as they transit the ionosphere, and by processing the collected data with sophisticated software, the researchers were able to detect the small effect that the explosion-induced atmospheric waves had on the distribution of the ionosphere’s electrons.
The same technique is being used by the researchers and others to study the ionospheric effects from natural hazards such as tsunamis, earthquakes, and volcanic eruptions.
A team from The Ohio State University and Miami University are engaged in a similar project.
Richard B. Langley is a professor in the Department of Geodesy and Geomatics Engineering at the University of New Brunswick (UNB) in Fredericton, Canada, where he has been teaching and conducting research since 1981. He has a B.Sc. in applied physics from the University of Waterloo and a Ph.D. in experimental space science from York University, Toronto. He spent two years at MIT as a postdoctoral fellow, researching geodetic applications of lunar laser ranging and VLBI. For work in VLBI, he shared two NASA Group Achievement Awards.
Professor Langley has worked extensively with the Global Positioning System. He has been active in the development of GPS error models since the early 1980s and is a co-author of the venerable “Guide to GPS Positioning” and a columnist and contributing editor of GPS World magazine. His research team is currently working on a number of GPS-related projects, including the study of atmospheric effects on wide-area augmentation systems, the adaptation of techniques for spaceborne GPS, and the development of GPS-based systems for machine control and deformation monitoring. Professor Langley is a collaborator in UNB’s Canadian High Arctic Ionospheric Network project and is the principal investigator for the GPS instrument on the Canadian CASSIOPE research satellite now in orbit.
Professor Langley is a fellow of The Institute of Navigation (ION), the Royal Institute of Navigation, and the International Association of Geodesy. He shared the ION 2003 Burka Award with Don Kim and received the ION’s Johannes Kepler Award in 2007.