It's been known for some time that commercial microwave links between cell phone towers, or base-stations, offer insight into weather conditions. Rainfall in the transmission path between stations attenuates the signal level, and these power fluctuations provide a measure of the intensity of the precipitation.

Researchers are increasingly using this correlation to supplement conventional measurements of rainfall. But there's scope to do more with the data by incorporating the numbers into hydrological models, as the Karlsruhe scientists demonstrated for streamflow in the River Ammer in the German Alps.

In a study published in Environmental Research Letters (ERL), the team examined the additional value of combining the signal attenuation data with rain gauge observations.

Including the precipitation data derived from commercial microwave links significantly improved river discharge simulations, reproducing features that conventional rainfall monitoring gauges were not able to capture on their own.

The signal attenuation data can be made available in real time and can provide insight into areas where the network of conventional rain gauges is limited.

"The continuous operation of rain gauges is quite expensive," Gerhard Smiatek of the Institute of Meteorology and Climate Research told environmentalresearchweb. "Today there are still many stations worldwide that require the data to be read out manually. Automatic versions require some degree of infrastructure for power and stable data transfer, as well as a budget for maintenance."

As mobile phone infrastructure providers become more involved with research groups in this area, Smiatek hopes to see further improvements in the technique. Examples include increasing the availability of higher-resolution signal level records, and sampling the attenuation signal directly at the hardware level.

The team hopes to expand the project to create a precipitation map that covers all of Germany, offering microwave link-derived analysis in near real-time for hydrological decision making.

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