The US government has begun auctioning of radio frequencies to be used for the next-generation communications network known as the 5G. However, some of these frequencies are close to the frequencies that satellites use for important earth observations ̵
If regulators or telecommunications companies fail to take measures to reduce the risk of disruption, observing satellites flying over 5G radio ranges across the United States can not accurately capture the concentrations of water vapor in the atmosphere. Meteorologists in the United States and other countries rely on this data to feed into their models. Without this information, weather forecasts are likely to suffer worldwide.
"This is a global problem," says Jordan Gerth, a meteorologist at the University of Wisconsin-Madison.
The US Department of Oceania and Atmospheres (NOAA) and NASA are currently in negotiations with the Federal Communications Commission (FCC), which oversees wireless US networks. NOAA and NASA have asked the FCC to work with them to protect the earth observation spectrum from interference when 5G is rolling. However, the FCC auctioned off the first part of the 5G spectrum with minimal protection. The sale ended on April 17, earning nearly $ 2 billion.
Sharing the sky
With the United States as such a communications market, government decisions on the use of 5G may influence global discussion on how to regulate technology. Supervisors from around the world will gather in Egypt's Sharm el-Sheikh from October 28 to draw up international agreements for which companies can use frequencies for 5G broadcasts and which interference with Earth observation frequencies is acceptable.
Astronomers, meteorologists, and other scientists have spent a long time working on sharing the spectrum with other users, sometimes switching to different frequencies to avoid conflict. "However, this is the first time that we see a threat to what I would call the crown jewels of our frequencies – the ones we absolutely must defend," says Stephen English, meteorologist at the European Center for Medium-Range Weather Forecasts in Reading , UK.
They contain the frequency of 23.8 gigahertz, where water vapor in the atmosphere gives off a weak signal. Satellites, such as the European MetOp probes, monitor the energy radiated from Earth at this frequency to determine the humidity in the underlying atmosphere – measurements that can be made during the day or at night, even when there are clouds. Predictors feed these data into models to predict how storms and other weather systems will evolve over the coming hours and days.
But a 5G station transmitting at almost the same frequency produces a signal very similar to that of water vapor. "We do not know that this signal is not completely natural," says Gerth. Forecasts would be more inaccurate if meteorologists included these bad data in their models.
The last FCC auction used two frequency groups: one between 24.25 and 24.45 gigahertz and the other between 24.75 and 25.25 gigahertz. Wireless devices transmitting near the lower end of this range could interfere with 23.8 gigahertz water vapor measurement. The FCC did not respond to the request of Nature of Nature to comment on the matter.
The situation resembles a loud neighbor next door, says Gerth. If this person beats music, there will probably be a lot of noise bleeding through the wall into your apartment. However, if you can persuade the person to suppress their music, you can sleep more peacefully.
Radio frequency engineers measure noise in decibels-watt units. The regulators set controls that limit the allowable noise. Negative numbers indicate increasingly stringent controls. At the FCC auction, a noise limit of -20 decibels watts was set for the US 5G grid. This is much louder than the thresholds almost all other nations consider for their systems. For example, the European Commission has agreed on -42 decibels watts for 5G base stations, and the World Meteorological Organization (WMO) recommends -55 decibels watts.
Many hope that the WMO figures will cause regulators to take strict global control noise standards at the meeting in Egypt. Due to the magnitude of the scale, the US proposal would allow more than 150 times more noise than the European proposal – and more than 3000 times more than the WMO plan, says Eric Allaix, a meteorologist at Météo-France in Toulouse, who is a WMO leads steering group for high-frequency coordination.
There is relatively little research into how bad weather forecasts can be, as interference at 23.8 gigahertz and other frequencies important for earth observation increases, says Gerth. "The more we lose, the bigger the impact will be," he says.
The NOAA and NASA have reportedly completed a study on the effects of varying levels of noise, which, however, at least did not publish a formal request from Congress. A 2010 National Academies of Sciences, Engineering and Medicine report concluded that a loss of scientific access to the 23.8 gigahertz signal would eliminate 30% of all useful data in microwave frequencies, significantly adding to the global weather forecast contributes.
And if atmospheric data from the United States is missing, it can dramatically affect forecasts for Europe, whose weather patterns are often controlled three to four days earlier by conditions in the United States, English says.
The Department of Commerce overseen The NOAA said it strongly supports the government's policy of promoting US leadership in secure 5G networks while maintaining and improving critical state and scientific missions. NASA Administrator Jim Bridenstine declined to comment, but commented in detail on his concerns over 5G at an agency meeting earlier this month. "That's a big deal," said Bridenstine.
The FCC plans to launch its next 5G auction, which will be the country's largest ever in December. It will include three additional frequency bands, some of which will be used for satellite observations of precipitation, sea ice and clouds.
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