Cooperative Institute for Research in Environmental Sciences
Friday, April 22, 2016

From The Archives: Crowdsourcing Earth's Magnetic Field

Citizen scientists using smart phones to help geophysicists

Happy May—Bike to School and Bike to Work days fall this month! Back in December 2014, we wrote about CrowdMag, a new citizen science effort that has geophysicists asking smart phone users around the world for help mapping Earth’s magnetic field. In honor of spring's cyclists and walkers, who collect terrific magnetic data, we're reposting an adapted version of this earlier story and hoping to get new citizen scientists on board!


San Francisco––During the fall meeting of the American Geophysical Union, Dr. Manoj Nair asked people around the world to download the CrowdMag application. The app takes advantage of the digital magnetometers embedded in smart phones.

“Our goal is to see if low-quality but high-frequency magnetic measurements around the world can help us improve navigation systems,” said Nair, who is a scientist with CIRES and works in NOAA’s National Centers for Environmental Information.

Image removed.iTunes / Google Play

Earth’s magnetic field shifts continually, rippling as a gust of solar wind arrives from the sun or shifting with the construction of a new underground pipe. For those who want to protect infrastructure from damage by space weather, or those who simply want to make better navigation systems, it’s critical to understand such magnetic field dynamics.

Right now, expensive instruments on satellites and stationary observatories help researchers and engineers take measure of the planet’s magnetic field. Those data can be extremely accurate, but they’re very limited in time and space. Even a satellite can probe only one region at a time.

Enter the smart phone with a map app! Across the planet, more than 1 billion people carry smart phones with digital magnetometers. These are not sophisticated instruments, but they’re generally accurate enough to tell a person whether she’s walking north or east, or if her meeting is in the building on this side of the highway or the other.

“The question we have is if we can reduce the noise in our measurements by making a lot of them,” Nair said.

The work may help improve navigation systems, and it may also help researchers better understand the shifting magnetic field itself, he said. For example, right now, when a shock wave of space weather arrives at Earth, Nair said, it’s impossible to know how the entire magnetic field around the planet responds. Better understanding that response—with simultaneous measurements distributed around the planet—could help power line operators know when they’re vulnerable to induced currents, or let oil drillers know when their navigation tools will be unreliable.

And better understanding geographic variation is important, too—a buried iron pipe below a street can send a map app—and its user—in the wrong direction, by affecting the magnetic field. Mapping such locations through crowdsourcing could improve digital wayfinding, too.

This is an experiment in progress: It’s not yet clear if mobile digital magnetometers will be accurate enough to help scientists understand magnetic field dynamics. “If we can reduce the noise, smartphone measurements will be integrated into mathematical models describing the space and time variations of the Earth's magnetic field,” said Dr. Arnaud Chulliat, a CIRES scientist and a co-investigator in this project. “So that is one of our long-term goals.”

CrowdMag can be downloaded through iTunes or Google Play.