Sunspot AR 12192 is the largest active sunspot in 24 years. It is about 20 times the surface area of Earth has has recently produced six solar flares, the largest of which produced as much energy as a billion thermonuclear weapons.
The Wall Street Journal has reported that these solar flares can affect the pick up of gps signals from satellites. For cyclists using Garmins or other GPS computers, the consequences obviously aren’t as important as they are for airline pilots, but according to experts there could be anomalies in ride data.
“All GPS units can be affected,” said Bifford Williams, a research scientist at Global Atmospheric Technology and Sciences. “GPS works by timing signals from multiple satellites to determine your distance from each satellite and triangulate your position. Flares and coronal mass ejections can deposit particles (electrons, ions) in the upper atmosphere concentrated towards the poles that change the index of refraction which can delay or change the angle of the signals. Too strong an ionized layer can block the signals completely.”
“The effect depends on the accuracy you need, how many satellites are in unobstructed view, and if you can tolerate intermittent dropouts,” Williams said. “Flares will produce effects that are highly variable in time and space, but mostly at higher latitudes.”
So how much will your data be affected? Garmin spokesperson Amy Nouri said that accuracy for the company’s GPS units is “typically better than 3 meters”, and that any solar-flare related issues would only result in “a slight decrease in accuracy for consumer grade GPS units, which is short lived and typically not observable by the consumer”. Garmin has not had any customer-reported issues.
More of an issue for users relying totally on gps, i.e. with no magnet sensor picking up ‘manual’ readings from the rotation of the wheel, is getting an uninterrupted view of the satellites in the first place. Solar flare activity is likely to result in a few seconds difference in results whereas cycling under trees or through tunnels will have a much more dramatic effect.
In short, I don’t think I can use it to explain away the extra 10 minutes it took me to cycle home yesterday. Perhaps I should have spent the last hour training rather than researching excuses!