Developing Countries Could Use Mobile Networks to Monitor Rural Rainfall
Researchers at the Wageningen University in the Netherlands have found that they can tap into information from mobile networks to accurately monitor rainfall over an area without the need for expensive metrological radar systems.
Apart from the convinced for humans out for a walk, accurate rainfall monitoring is necessary for agriculture, sewage and drainage systems and in some situations, even transport networks.
What the researchers found was that while it has long been understood by telecoms engineers that rainfall affects radio signals, the network of microwave based backhaul links used in mobile networks is often sufficient dense and reliable enough to provide interference data.
By logging how each microwave link is affected by rainfall, the researchers were able to plot accurate maps of the rainfall that matched those coming from conventional radar services. The research was able to tap into around 2,400 microwave links crossing the Netherlands operates by T-Mobile.
The system was based on monitoring the amount of power received from a known transmitter from which they can infer not just the rainfall level, but also the average size of raindrops -- light shower vs thunderstorm -- although some processing was also needed to eliminate false positives from other weather effects.
The research noted that in general, the number of microwave links in a country will be much larger than the number of automatic, or even daily, rain gauges, providing new opportunities to adjust radar data.
They did note thought that the technique might be less useful in the tropics, where microwave links operate at lower frequencies and the error margin of the data is adversely affected.
The key advantage of the technique is how it could be deployed in developing countries where microwave backhaul is more common, and where rainfall monitoring is less extensive, while also being more important.
This isn't the first time that mobile networks have been used to monitor unrelated events - scientists at Siemens' Roke Manor Research site reportedly developed a technology that can use a cellular network to reveal the locations of military aircraft that use stealth technology.
There were -- obviously unconfirmed -- reports that the downing of an F117A stealth jet during the Bosnian campaign was thanks to monitoring of the mobile network interference patterns.