LOS ANGELES -- As atmospheric rivers dumped record volumes of rain on California this spring, emergency responders used the federal government's satellites to warn people about where the storms were likely to hit hardest.
Many government scientists say such warnings may become a thing of the past if the Trump administration's Federal Communications Commission pushes forward with plans to auction off radio frequency bands adjacent to one that weather forecasters use.
In May, the FCC finished accepting bids on a radio frequency bandwidth that agency officials say will enable U.S. companies to compete in the 5G wireless field, which offers the tantalizing prospect of a much faster, more reliable cellphone signal. Nearly 30 cellular companies bid on nearly 3,000 licenses, bringing in more than $2 billion.
That band -- 24 gigahertz -- sits right next to one that federal scientists use to detect water vapor emissions in the atmosphere. Officials with NASA and the National Oceanic and Atmospheric Administration worry 5G traffic in the adjacent band will interfere with their detection of the faint signal emitted by atmospheric water.
That will make it difficult for them to monitor, predict and forecast hurricanes and dangerous weather events such as California's atmospheric rivers, said Marty Ralph, a research meteorologist at Scripps Institution of Oceanography at the University of California, San Diego.
The science agencies aren't suggesting the FCC stop pursuing 5G in the 24-GHz band. Instead, they disagree with the communications agency about how loud those signals can be.
FCC officials set a standard they believe will keep the 5G noise quiet enough for NOAA and NASA to keep "hearing" atmospheric water vapor.
But the federal science agencies say it's not enough -- by a factor of 5,000.
In May, Neil Jacobs, NOAA deputy administrator, told a congressional committee that the FCC's move threatens to kill 77% of the data the agencies acquire from their passive microwave sounding instruments and degrade forecasting accuracy by 30%.
NASA's administrator, Jim Bridenstine, was even more cautionary at an agency town hall meeting in April. He told the audience of scientists and engineers that interference from 5G could bring forecasting accuracy back to levels not seen since 1978.