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Cellphone masts can measure rainfall

作者:宇文维    发布时间:2019-03-02 06:01:09    

By Tom Simonite Cellphone masts could provide a cheap yet accurate way for weather forecasters to get live rainfall information. Monitoring the way rain interferes with the signals routinely sent between phone masts provides an accurate picture of rainfall over an area, say Israeli researchers. The same technique could one day also be used to measure pollution, they suggest. In order to manage calls efficiently, cellphone masts constantly send microwave radio messages to each other. But water molecules absorb this microwave energy, meaning rainy weather can disrupt these messages. Each mast already effectively collects this information because it must continually adjust the strength of its signal to correct for interference. “You can extract useful information about rainfall from how much a signal is reduced,” explains Hagit Messer-Yaron, an electrical engineer from Tel-Aviv University, Israel, who led the research. To see how accurately the technique could be used to monitor rainfall Messer-Yaron and colleagues analysed data gathered over 24 hours by masts belonging to a major Israeli cellphone operator covering an area 3 by 7 kilometres. They then compared this data with measurements collected using conventional weather radar and rain gauge instruments. The researchers discovered that the phone masts produced very similar results to rain gauges, which are currently the most accurate way of measuring rainfall. But the masts were found to be more accurate than weather radar instruments. “By using this technique we gain a very cheap detection system,” says Messer-Yaron. “It also covers places that are not covered already by gauges.” And cellphone masts can also provide measurements every 15 minutes, while even rain gauges typically take measurements only once every 30 minutes. Messer-Yaron hopes the technique could eventually be used to measure more than rain: “In future it will be possible to record different sources of interference, like different types of precipitation, or pollution.” This would require more sophisticated analysis of the data collected by masts. But Messer-Yaron says it might be possible to tease out useful information concerning snowfall, sleet or pollution by studying different microwave frequencies. Dawn Harrison, a weather expert from the UK government’s Meteorological Office notes that microwave signals have been used for meteorological measurements in the past. In September 2005, UK researchers used specially built microwave masts calibrate radar instruments. Harrison adds the technique also has a key limitation – it only performs measurements in a straight line between masts. “Microwave data should be viewed as complementary to radar and rain gauge data, rather than a replacement,” she told New Scientist. “A weather radar network offers 3D coverage”. Radar instruments also collect data from over the ocean, which Harrison says is “essential for the accurate forecasting of weather”. Journal Reference:

 

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