The ITU and the World Meteorological Organization have published the 2026 edition of their spectrum handbook for meteorology, and its timing is deliberate: it lands as regulators prepare for WRC-27, where agenda item 1.7 will consider new IMT identifications in the 4.4–4.8 GHz, 7.125–8.4 GHz and 14.8–15.35 GHz bands.

The handbook, launched this week at the opening of a three-day global seminar in Geneva, provides a detailed overview of the characteristics, spectrum use and interference scenarios of all meteorological services. It was prepared by ITU-R Working Parties 7C and 7B together with ET-RFC, and for each system it sets out the bands used, the criteria for predicting harmful interference and the likely impact on forecasts and warnings.

ITU secretary-general Doreen Bogdan-Martin said the handbook "sets out the spectrum needs of these systems, creates a common language between our two communities, and gives the world a stronger basis for informed decision-making when it comes to spectrum use for meteorology".

What is at stake

Alec Casey, co-vice-chair of WMO's Expert Team on Radio Frequency Coordination, used the Geneva seminar to set out the WMO's preliminary position on agenda item 1.7. The 7.125–8.4 GHz range contains three satellite downlink bands: 7450–7550 MHz for geostationary MetSats, 7750–7900 MHz for non-geostationary MetSats and 8025–8400 MHz for Earth exploration satellite services (EESS).

Casey warned that IMT in these bands "could cut off access to satellite data from Meteosat, GOES, JPSS and other systems unless significant exclusion zones are implemented around MetSat/EESS earth stations". He added a point that will weigh on every negotiator in the run-up to Shanghai: "IMT deployment is effectively irreversible at scale."

The WMO opposes IMT identification in all three downlink bands. It also does not support identification in 7125–7250 MHz, which overlaps the 7075–7250 MHz range used by passive sensors to measure sea surface temperature. It further wants the impact on proposed new EESS passive allocations at 4.2–4.4 GHz and 8.4–8.5 GHz, under consideration in agenda item 1.19, taken into account.

Why protection is hard

Polar-orbiting weather satellites illustrate the difficulty. Beyond sending full data to a few main ground stations, they broadcast live to any receiving station they pass over — a practice called "direct read-out" that gets fresh observations to forecasters within minutes. The newest satellites produce far more data than the traditional 12 MHz-wide band at 1698–1710 MHz can carry. The handbook states that the 150 MHz-wide band at 7750–7900 MHz "has to be used" — and that band sits inside the range proposed for IMT.

The main polar-orbiting systems already use it or plan to. US JPSS and Suomi-NPP satellites broadcast at 7812 MHz. China's FY-3 series transmits between 7780 and 7860 MHz. Europe's new Metop-SG satellites will use the whole band. The handbook notes that stations receiving these transmissions "can be located anywhere". A few main ground stations can be shielded from mobile networks with exclusion zones, but receivers scattered worldwide cannot easily be protected.

On passive sensing, the handbook lists 6425–7250 MHz as a band of interest for ocean surface temperature with "no allocation". Measurements around 6 GHz "offer the best sensitivity to sea surface temperature". The handbook also explains why passive sensors are exposed to mobile networks: "while a single terrestrial emitter may not radiate enough power to cause errors in passive sensing measurements, a large number of these emitters may be harmful." It names IMT as one source of this aggregate interference.

Markus Dreis, chair of ITU-R Study Group 7, framed the systemic risk: degradation of any radio component in the global system, "whether related to observation or data dissemination, can jeopardize the entire Earth system monitoring and prediction process".

The economics of interference

Vadim Nozdrin, counsellor of ITU-R study groups at the Radiocommunication Bureau, described IMT in 6425–7250 MHz as one of the "new interference scenarios" facing SST measurements and warned of "latecomer costs" for services forced to adapt to new neighbours. These include higher capital spending on "bigger antenna size, restricted parameters, more expensive equipment, shielding, specialised software", plus higher operating costs for "more qualified staff, advanced signal processing methods, more power, more coordination requirements".

He also set the economic stakes side by side. The US auction of 280 MHz in the 3.7–3.98 GHz band raised $81.2 billion in 2021. Meteorological observations save more than 1,200 lives a year in the US. "Protection of the radio spectrum for meteorology and Earth observation is essential to ensure that public investments translate into real-world benefits," he said.

WMO holds only observer status at World Radiocommunication Conferences, and Casey said its position paper "is the voice of the global meteorological community". WMO's INFCOM-4 is due to endorse the preliminary position in November, with the WMO Congress adopting the final position in June 2027 ahead of WRC-27 in Shanghai in October and November 2027. As Natalia Donoho, chief of the WMO Space Programme Section, put it: "Spectrum decisions made today affect the observations, forecasts and warnings available tomorrow."