Phone masts make weather forecasts

Wageningen University & Research, the Royal Netherlands Meteorological Institute (KNMI) and water research institute Deltares have used the signal strength of commercial mobile phone masts to accurately measure rainfall between two points. It also allowed them to make a weather forecast up to several hours ahead. The scientist derived the intensity of rain falling between two transmission masts from so-called radio beam connections in cell phone networks, aka commercial microwave links (CMLs).

“The communication companies are interested in having the clearest possible signal for mobile telephony. But we are looking at exactly the opposite,” explains Ruben Imhoff of the Wageningen research group Hydrology and Quantitative Water Management. The signal attenuation between two masts can be caused by rain between those two measuring points. “The harder it rains, the stronger the interference we get back in our data. We map out this disturbance and translate it into rain intensity, and then into very short-term precipitation forecasts, so-called nowcasting.”

The research team compared the data from KNMI rain radars, such as those used by Buienradar, with the data from the masts of the telecom companies on twelve days with rain. “We were pleasantly surprised when we saw the results,” says Imhoff. “The CML method turns out to work quite well, even at high precipitation intensities.” Sometimes the precipitation forecasts were even better than those of the rain radar, especially with heavy rainfall. “But then you have to take into account that the operational rain radar products weren’t corrected for anomalies. There’s still room for improvement in the case of radar as well, and we are working on that.”