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Solar cycle may disrupt GPS

Apr 6, 2007
 
Weather is an important topic for the average voyager. But weather has always just meant the kind one experiences at the surface of the Earth. Now, it seems, voyagers also need to know about weather in outer space. At a recent gathering of academic, government and private sector scientists, 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. The findings were announced on April 4th in Washington, D.C., at the first Space Weather Enterprise Forum, which was focused on examining the Earth's ever-increasing vulnerability to space weather impacts.

Solar radio bursts are caused by solar flares, which are vast eruptions of high-energy electrons from the sun. These flares then produce blasts of radio energy that cover the whole range of the radio frequency spectrum. This radio energy is interpreted by GPS and other radio receivers as noise and can interfere with normal operation.

An example of this disruptive occurred on December 6, 2006, (see image of solar flare above) when a major solar radio burst interfered with GPS reception for a large numbers of receivers. Cornell University scientists used a set of specially designed GPS receivers to make the first quantitative measurements of the effect of solar radio bursts on GPS receivers. The results of the December 6 event, along with data from previous, less intense radio bursts have produced an expectation among space weather scientists that the larger solar radio bursts expected during coming solar maximum, which peaks in 2011, would disrupt the operation of some GPS receivers.

"In December, we found the effect on GPS receivers were more profound and wide spread than we expected," said Paul Kintner, Ph.D., professor of electrical and computer engineering at Cornell University, in a NOAA press release. "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, in a NOAA press release. "Measurements with 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."

As for the potential effect on voyagers, it’s sobering that the December 6 radio burst was detected by the FAA’s Wide Area Augmentation System (WAAS). Although WAAS was not significantly degraded, this is reportedly the first time a solar radio burst had been detected by the system.

"Although our findings indicate the effects of this solar burst were less intense on WAAS than on other operational systems, mainly due to the robust system design, it is important for us to consider the potential impact of future, more powerful, solar radio bursts during periods of high solar activity," said Patricia Doherty, co-director and senior scientist, Institute for Scientific Research at Boston College, in a NOAA press release.

There are three 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," said Anthea Coster, Ph.D., MIT Haystack Observatory, in a NOAA press release. 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."