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| Earth on Feb 21, 2013

New way to measure rain using cell phone signals

Scientists can now measure rain from our cellular phone signals. They hope this technology will lead to improvements in early warning systems for floods.

Measurements of rainfall are declining over some regions of the world despite the fact that such data are critical for creating accurate weather forecasts and for managing water and agricultural resources. Now, scientists believe they have found a new way to measure rain from our cellular phone signals. With this new technology, scientists were able to reconstruct maps of precipitation intensity across the entire country of The Netherlands. Their research was published on February 19, 2013 in the journal Proceedings of the National Academy of Sciences.

Photo credit: Jonathan Kos-Reed

Rainfall measurements are critical for creating accurate weather forecasts and for managing water and agricultural resources. Unfortunately, many areas of the world lack good rain gauge networks, and the countries that do have extensive network coverage are cutting back on their data collection activities due to budget constraints.

Since about 2006, scientists have been exploring ways to measure rainfall from cellular communication radio signals. Our cellular phones send frequent radio signals from transmitting antennas to receiving antennas, and rain can interfere with those signals. When it’s raining, the raindrops absorb a portion of the radio wave and scatter some of its energy. This attenuation of the radio signals grows stronger as the number and size of raindrops increases. Hence, scientists can reconstruct rainfall data across a given area simply by knowing to what extent radio signals were attenuated between cell phone towers.

A Forestry Technician inspects a rain gauge. Image Credit: Molly Cavaleri, U.S. Forest Service.

A team of European scientists were able to use this new technology to reconstruct maps of rainfall intensity across the entire country of The Netherlands, which stretches over 35,500 square kilometers (13,514 square miles). This was one of the largest precipitation reconstruction projects attempted to date. They are hoping that such demonstration projects may lead to the creation of real-time rainfall monitoring networks in areas of the world that lack ground-based rain gauges. Such networks could be an important tool for improving early warning systems for floods, the scientists say.

Aart Overeem, lead author of the study, is a postdoctoral scholar affiliated with Wageningen University and the Royal Netherlands Meteorological Institute. Co-authors of the study included Hidde Leijnse and Remko Uijlenhoet. Their research was funded by The Netherlands Technology Foundation.

Rainstorm over the Fogg Dam Conservation Reserve, Australia. Image Credit: Bidgee via Wikimedia Commons.

Bottom line: Scientists have found a new way to measure rain from our cellular phone signals. With this new technology, scientists were able to reconstruct maps of precipitation intensity across the entire country of The Netherlands by knowing to what extent the rainfall attenuated radio signals. Their research was published on February 19, 2013 in the journal Proceedings of the National Academy of Sciences. They are hoping that such demonstration projects may lead to the creation of more real-time rainfall monitoring networks and improvements in early warning systems for floods.

Update: this article was updated on February 23, 2012 to clarify that rainfall can only be computed from the attenuation between cell phone towers and not from the attenuation between cell phones.

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