Rainfall monitoring - another app for mobile phone towers. Photo: MAX MASON-HUBERS
Cellular phone towers, vital in a world increasingly dependent on mobile communications, may provide another useful service: real-time monitoring of rainfall.
A paper published in the Proceedings of the National Academy of Sciences in the US Tuesday (AEDT) showed how rainfall affects the signal strength between transmitters and receivers on mobile phone towers – information that network operators constantly monitor.
As rain falls it absorbs radio signals travelling between towers, causing them to lose power. The Dutch researchers plotted rainfall data taken from this new method and pitted it against regular methods and found they closely matched.
The study, based on the cellular phone network in the Netherlands, said the potential use of such data may be strongest in developing nations where "ground-based rainfall sensors are often virtually absent" but where cellular phone towers are becoming more common as mobile phone use rockets.
"Monitoring rainfall using cellular telecommunication networks could provide a great opportunity to reduce fatalities and economic loss, (for example) by improving flood early warning systems," the authors, Aart Overeem, Hidde Leijnse and Remko Uijlenhoet, said.
Australia's Bureau of Meteorology said it is not currently exploring the use of mobile phone towers in collecting rain data.
"While the use of microwave attenuation from the microwave communications network is generally recognised as a possible way of mapping rainfall, there still appears to be a significant amount of work that needs to be done in a number of areas to bring the technology to a testable/usable level," said John Le Marshall, senior principal research scientist at the weather bureau.
"The technology is interesting and developments will be watched carefully by those interested in rainfall mapping," Professor Le Marshall said.
Steven Sherman, director of the Climate Change Research Centre at the University of NSW, said Australia was already covered by weather radars.
"The key thing is whether (the use of cellular phone towers) will be able to give us anything that rain radars don't give us," Professor Sherman said.
He said the service had "potential value" in mountain terrain, where radar coverage can be restricted. "There may be blind spots. A cellular network overcomes that because all the towers follow the topography."
The standardised collection of rain information would be also helped by the fact that commercial microwave links are similar worldwide, the report found.
"In addition, link-based rainfall estimates could serve as ground validation for, or complement, satellite retrievals above land, and hold a promise for assimilation in numerical weather prediction and forecasting models, as well as for comparison with climate models," the report found.
The authors expressed hope that the potential uses of the rainfall data might spur network operators to provide it for free. "Perhaps (inter)national legislation could also help achieve this goal," they said.