Hurricane Sandy turned west in 2012 before making landfall in New Jersey. Without microwave sensor data, forecasters would have called for the storm to make landfall 24 hours later than it did and to strike Maine. Credit: National Weather Service

SAN FRANCISCO – Less than a week before a Federal Communications Commission auction of radio frequency spectrum for 5G, FCC Chairman Ajit Pai clearly expressed impatience with the weather community’s ongoing concerns about interference and requests to modify the U.S. government’s position.

In a March 8 letter to Commerce Secretary Wilbur Ross and NASA Administrator Jim Bridenstine, Pai emphasized the Trump Administration’s commitment to rolling out 5G as soon as possible and freeing up spectrum for it.

The FCC is preparing to auction 2,909 licenses in the 24.25 to 25.25 bands of the electromagnetic spectrum on March 14. At the same time, the FCC is preparing the U.S. government’s proposal for the 2019 World Radiocommunications Conference (WRC) in Egypt starting in October. The U.S. plan for protecting passive microwave services from interference is far less stringent than plans published by other nations.

Ross and Bridenstine asked for further discussion of the U.S. position.

“The current FCC proposal would have a significant negative impact on the transmission of critical Earth science data – an American taxpayer investment spanning decades and billions of dollars,” they wrote in a Feb. 28 letter to Pai. “As the U.S. government continues to investigate additional spectrum for future commercial broadband use, it is essential that protections are established for the critical operations of NASA, the Department of Commerce and our international partners in the 23.6 to 24 GHz spectrum band.” The Commerce Department is home to the National Oceanic and Atmospheric Administration and the National Weather Service.

In the letter, Ross and Bridenstine ask Pai to remove the FCC’s published proposal from its website and to attend a March 11 interagency meeting at NASA headquarters “to continue the long-standing interagency reconciliation process on this important topic.”

In the March 8 letter, Pai rejected that invitation, saying the matter was settled. “Notwithstanding the absence of any technical basis for an objection over the past two years to the FCC’s well-established protection limits, NTIA [the National Telecommunications and Information Administration] declined to agree with the FCC’s balanced approach on this issue,” Pai wrote. To settle the matter, the State Department, acting as the arbiter, agreed with the FCC approach.

Pai further scolded the NTIA and NASA for “actively lobbying foreign delegations and key industry players” to undercut the FCC’s position. “Such actions are unacceptable,” he wrote.

Meteorologists have expressed concerns for many years about radio frequency interference but the debate is becoming more heated in 2019 due to the FCC’s planned auctions and the upcoming WRC meeting. The WRC brings together nations every three to four years to update international regulations on radio spectrum usage.

Meteorologists worry they will lose access to specific portions of the electromagnetic spectrum they rely on for Earth observation. The 23.6 to 24 GHz band, for example, is a key dataset for passive microwave sensors monitoring atmospheric water vapor, said Jordan Gerth, associate researcher at the University of Wisconsin’s Cooperative Institute for Meteorological Satellite Studies. Gerth also chairs the American Meteorological Society’s Committee on Radio Frequency Allocations.

The problem is the same spectral bands and adjacent bands also work well for 5G technology. If 5G moves into the same or adjacent bands, meteorologists worry about interference. Passive microwave sensors pick up an extremely faint signal that could easily be drowned out by transmission in an adjacent band.

“We’ve been burned several times by out-of-band emissions,” Sidharth Misra, microwave instrument scientist at NASA’s Jet Propulsion Laboratory, said at the American Meteorological Society conference in Phoenix in January. “They promise to not have out-of-band emissions. They fail. It’s too late. We lose a science channel.”

NASA, NOAA and meteorologists outside government are eager to prevent that from happening again because microwave sensors provide one of the most important datasets for forecasting. Without microwave sensor data, forecasters would not have been able to predict the path of Hurricane Sandy, which struck the Eastern seaboard in 2012, researchers said at the American Meteorological Society conference.

Debra Werner is a correspondent for SpaceNews based in San Francisco. Debra earned a bachelor’s degree in communications from the University of California, Berkeley, and a master’s degree in Journalism from Northwestern University. She...