Dutch researchers say they have discovered a way to use mobile phone networks to measure rainfall.
Aart Overeem from the Royal Netherlands Meteorological Institute decided to pursue a lower-cost alternative to rain measurement after the depletion of traditional rain gauges worldwide in recent years made the collection of accurate data difficult.
Mr Overeem said researchers had wondered whether they could use the microwave radio links that transmit mobile phone calls to measure rainfall.
"It had already been known for a long time that rainfall can influence the strength of the signal in telecommunication," Mr Overeem said.
"For instance by the end of the '90s, some colleagues of mine already had what you call a research link in which they showed that the signal gets weaker in case of rainfall," he said.
"In case of a radio link, electromagnetic signals travel from the antenna of one telephone tower to the antenna of another telephone tower.
"When it starts raining the signal gets weaker, so the more rain droplets and the larger the size of the rain droplets, the larger the decrease in the received signal power that's one end of such a microwave link." In a study published today in the Proceedings of the National Academy of Sciences, Mr Overeem conducted tests across 12 days before comparing the phone network data with rainfall data collected the old fashioned way.
"It appeared to be already quite accurate, although more research is probably needed to get reliable rainfall maps all year round." Once additional work is done, Mr Overeem said the new rainfall measurement technique could become widespread very quickly.
"For instance in Africa, people often have a mobile phone, there is an infrastructure, and there are some telecommunication networks, but the number of rain gauges is quite low," he said.
"So particularly for those countries, it will be quite interesting.
"For other countries [that] do have weather radars, such as countries in Europe, the United States and Australia, this microwave link data could be interesting to adjust the radar rainfall images." He said weather radars, with their ability to provide detailed measurements over large areas, were very useful and could be used for managing the response to floods.
Researchers hoped the use of mobile phone data would receive approval by phone companies to make the information available.