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Interfering with the Global Positioning System

Press Release From: American Geophysical Union
Posted: Tuesday, June 10, 2008

WASHINGTON -- You can't always trust your GPS gadget. As scientists have long known, perplexing electrical activity in the upper atmospheric zone called the ionosphere can tamper with signals from GPS satellites.

Now, new research and monitoring systems are clarifying what happens to disruptive clouds of electrons and other electrically charged particles, known as ions, in the ionosphere. The work may lead to regional predictions of reduced GPS reliability and accuracy.

One team of researchers has recently observed Earth's aurora, which is a prominent manifestation of ionospheric electrical activity, in the act of disrupting GPS equipment. Other scientists have successfully tested a way to forecast GPS disturbances for marine users, with likely extension to users on land.

Some research groups are turning the tables and employing GPS receivers as tools with which to conduct basic research on the electrical-current structures of the ionosphere.

The scientific reports on these and other recent developments are available in a special section of Space Weather: The International Journal of Research and Applications, a publication of the American Geophysical Union, or AGU.

A magazine-style article that introduces the section was posted online Friday, June 6. It summarizes past research and operational developments regarding ionospheric effects on GPS, and discusses potential future improvements in the field.

The new introductory article is available at http://www.agu.org/journals/sw/swa/free (Click on "Space Weather and the Global Positioning System"). The special section itself, which currently contains seven scientific reports, is available online at http://www.agu.org/journals/sw/?content=specialsections&ssid=GPS1

Space Weather is an online journal devoted to studies of the electrical interactions between the Earth and various emissions from the Sun, including electrically charged particles (the solar wind), solar radio noise and solar X-rays. The journal, which has a quarterly print digest called Space Weather Quarterly, is cosponsored by the National Science Foundation and the International Space Environment Service.

AGU is an international organization of Earth and space scientists. It has more than 50,000 members in 137 countries, and publishes Space Weather and 18 other scientific journals.

Notes for Journalists Journalists and public information officers who are registered with AGU can directly download a PDF copy of any of the reports included in the special section. (Just click on the links provided on the special section's web page, whose web address is given above.)

Nonregistered reporters may also receive a PDF copy of any report by emailing Peter Weiss at pweiss@agu.org. Please provide your name, the name of your publication, and your phone number.

The scientific paper on the auroral effect is "GPS scintillation in the high arctic associated with an auroral arc", by Smith et al., http://dx.doi.org/10.1029/2007SW000349

The paper on marine GPS forecasts is "Potential for issuing ionospheric warnings to Canadian users of marine DGPS", by Skone and Coster, http://dx.doi.org/10.1029/2007SW000336

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