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Urban magnetic fields reveal clues about energy efficiency and pollution

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Examining a city’s magnetic footprint can be used as an early warning system for detecting environmental issues caused by pollution and as a tool for optimising energy conservation, researchers have said.

Researchers from Germany and the US compared urban magnetic fields between two US cities: Berkeley, California, and the Brooklyn borough of New York City.

They looked at what kinds of information can be extracted using data from magnetic field sensors to understand the working of cities. Magnetic field activity from various sources could provide insight into what is going on during a 24-hour period, the researchers said.

“A city is viewed as a physical system akin to a distant astronomical object that can be studied using a variety of multispectral techniques,” said Vincent Dumont, from Lawrence Berkeley National Laboratory. “In short, our project was inspired by our desire to apply what we learned practising fundamental physics research to the study of cities.”

Researchers collected magnetic field data continuously during a four-week period, using synchronised measurements with a network of sensitive magnetometers. Data was processed and analysed using modern data analysis techniques.

In their current work comparing two very different cities, Brooklyn and Berkeley, they discovered Berkeley reaches a near-zero magnetic field activity during the night, while Brooklyn’s magnetic activity continues day and night.

“Again, not too surprisingly, we discovered that ‘New York never sleeps,’ or more seriously, there are indeed a number of magnetic signatures specific to each city,” he said.

The researchers hope their network magnetometry and smart data analysis combination can become a valuable tool for multidisciplinary urban science.

“This work builds on our earlier experiments conducted around the city of Berkeley, in the San Francisco Bay Area,” Dumont said. “We identified the dominant sources of magnetic signals – which, not too surprisingly, turned out to be the trains of the Bay Area Rapid Transit (BART) system, and learned to glean weaker signals from this dominant background.”

“We hope this line of research will be picked up and further developed both by the members of our team as well as others, hopefully within cities around the world,” he said.

In March, the Australian city of Melbourne unveiled a new traffic-management system using the latest technology to reduce traffic jams and improve road safety.

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