What's needed to keep 5G from compromising weather forecasts
Researchers from Rutgers University have shown that 5G signals that “leak” into the spectrum used by satellite sensors can lead to inaccurate weather forecasts.
Passive sensors on National Oceanic and Atmospheric Administration satellites use the 23.8 GHz spectrum to measure water vapor. These measurements rely on detecting the strength of the water vapor’s microwave radiation, which is particularly vulnerable to active signals in nearby spectrum bands.
5G communications use the adjacent n258 band, which is at 26 GHz, and radiation accidently leaking into the 23.8 GHz spectrum risks negatively affecting the accuracy of weather forecasts, aircraft flight path planning and oceanographic data for civilian and defense ships, according to an August Congressional Research Service report.
NASA and NOAA have argued for tighter limits on stray radiation, but the administration is pushing for more relaxed rules on leakage as it expands commercial use of the spectrum.
To maintain the accuracy of the satellite based weather forecasts, the Rutgers researchers said, 5G leakage must be precisely characterized. In their paper, they explain how the 5G signal energy affected the accuracy of forecasting of precipitation (by up to 0.9 millimeters) and temperatures near ground level (by up to 2.34 degrees Fahrenheit). The calculations were based on a computer model forecasting the deadly 2008 Super Tuesday Tornado Outbreak in the South and Midwest. Such variation is significant enough to warrant deeper investigation of the impact of 5G operation on weather forecasting and means to mitigate it, they said.
“It can be argued that the magnitude of error found in our study is insignificant or significant, depending on whether you represent the 5G community or the meteorological community, respectively,” said senior author Narayan B. Mandayam, chair of the Department of Electrical and Computer Engineering at Rutgers University–New Brunswick.
To enhance coexistence of 5G systems and reliable weather forecasting, the researchers called for improving and updating data assimilation and weather prediction models and adapting them based on the “dynamics of 5G systems in time, space, and frequency.”
“One of our takeaways is that if we want leakage to be at levels preferred by the 5G community, we need to work on more detailed models as well as antenna technology, dynamic reallocation of spectrum resources and improved weather forecasting algorithms that can take into account 5G leakage,” Mandayam said.
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