During an unprecedented solar eruption last December, researchers at Cornell University confirmed solar radio bursts can have a serious impact on the Global Positioning System (GPS) and other communication technologies using radio waves. 

Solar radio bursts begin with a solar flare that injects high-energy electrons into the solar upper atmosphere.  Radio waves are produced which then propagate to the Earth and cover a broad frequency range.  The radio waves act as noise over these frequencies including those used by GPS and other navigational systems which can degrade a signal.

Forecasters from the U.S. National Oceanic and Atmospheric Administration (NOAA)’s Space Environment Center in Boulder, Colo., the U.S.A., observed two powerful solar flares on December 5 and 6, 2006.  These violent eruptions originated from a large sunspot cluster identified by NOAA.

On December 6, 2006, a solar flare created an unprecedented intense solar radio burst causing large numbers of receivers to stop tracking the GPS signal.  Using specially designed receivers built at Cornell University as sensitive space weather monitors, Cornell scientists were able to make the first quantitative measurements of the effect of earlier solar radio bursts on GPS receivers.  Extrapolations from a previous moderate event led to the prediction that larger solar radio bursts, expected during solar maximum, would disturb GPS receiver operation for some users.

“In December, we found the effect on GPS receivers were more profound and widespread than we expected,” said Paul Kintner, Ph.D., professor of electrical and computer engineering at Cornell University.  “Now we are concerned more severe consequences will occur during the next solar maximum.”

“This solar radio burst occurred during the solar minimum, yet produced as much as 10 times more radio noise than the previous record,” said Dale Gary, Ph.D., chair and professor of the physics department at New Jersey Institute of Technology.  “Measurements with the New Jersey Institute of Technology (NJIT)’s solar radiotelescope confirmed, at its peak, the burst produced 20,000 times more radio emission than the entire rest of the Sun. This was enough to swamp GPS receivers over the entire sunlit side of Earth.”

The Global GPS Network, a set of precise GPS receivers used for a variety of scientific and real-time applications, was also affected by this solar disturbance.  These applications include a very high accuracy positioning service that can provide a user’s position with 10 to 20 cm accuracy anywhere in the world, on land, in the air or in Earth’s orbit.

3 Key Points to Remember about Solar Radio Bursts.

“First, society cannot become overly reliant on technology without an awareness and understanding of the effects of future space weather disruptions.  Second, the December 6 event dramatically shows the effect of solar radio bursts is global and instantaneous.  Third, and equally important, the size and timing of this burst were completely unexpected and the largest ever detected.  We do not know how often we can expect solar radio bursts of this size or even larger,” said Anthea Coster, Ph.D., MIT Haystack Observatory.

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