New Radio Regulations generally recognize WMO needs
The World Meteorological Organization generally welcomes important updates to the international agreement on radio frequency bands, which are vital for weather forecasts and early warnings, as well as climate monitoring and “space weather” services.
The World Radio Communication Conference in Dubai ended on 15 December after four weeks of negotiations to update the Radio Regulations, the global treaty which governs radio spectrum and satellite orbits.
“The WMO delegation in Dubai achieved excellent results during WRC-23 fully in line with the WMO position paper approved at the World Meteorological Congress in May 2023,” said Natalia Donoho, Head, Space Systems and Utilization Division, WMO.
The conference outcomes are of vital importance to the WMO community. Access to the radio frequency spectrum is critical to the meteorological and hydrological infrastructure that underpins weather and related environmental services worldwide. Satellites, weather radar, radiosondes, hydrological observing systems, and drifting buoys all operate based on radio or microwave transmissions – and there is increased competition from emerging technologies.
From a meteorological and climate-monitoring perspective, the most critical issues concern the measurement of sea surface temperature and the observations of space weather.
Recognition of space weather
Space-weather observations are essential for the detection of solar events and their impacts on Earth, which can cause severe disruptions to critical infrastructure both on Earth and in space, resulting in radio blackouts, damage to satellites, perturbations in power grids, and increased radiation exposure on trans-polar aircraft routes.
WMO therefore welcomes the recognition at WRC-23 of space weather sensors in the Radio Regulations.
Space Weather observations are now defined in the context of the Radio Regulations through a new WRC-23 Resolution on the Importance of space weather sensor systems incorporated by reference via a new Article 29B Radio service related to space weather observations. This has allowed to associate space weather with a dedicated “radiocommunication service” – namely MetAids (space weather). This is an important first step achieved.
WMO also welcomes the fact that a new agenda item for WRC-27 has been obtained, proposing studies towards new MetAids (space weather) allocations in frequency bands used by operational receive-only space-weather sensors that require protection.
Studies will be performed in the next four years regarding potential primary allocations of several frequency bands in the MetAids (space weather) service (27.5-28 MHz, 29.7-30.2 MHz, 32.2-32.6 MHz, 37.5-38.325 MHz, 73.0-74.6 MHz, 608-614 MHz).
Continuity of SST measurements
Sea surface temperature (SST) is a vital component of the climate system, with a major influence on interaction between oceans and the atmosphere. SST, as one of the main drivers of ocean circulation, is crucial for numerical weather and ocean prediction models. The 6/7 gigahertz (GHz) frequency range — corresponding to peak SST sensitivity — is currently being utilized for passive ocean remote sensing from satellites.
Under WRC-23 agenda item 1.2, 6 425-7 075 MHz and 7 075-7 250 MHz frequency bands were identified for International Mobile Telecommunications (IMT). Studies demonstrate that SST measurements could be severely hindered by such deployment.
To mitigate this risk, WMO has identified other potential bands for SST measurement that could be used in combination with the 6/7 GHz range. A new agenda item for WRC-27 was obtained to study possible new primary allocations to the Earth Exploration Satellite Service (passive) in the bands 4 200-4 400 MHz and 8 400-8 500 MHz. This new agenda item provides a lifeline to the Sea Surface Temperature measurements that are so critical for Numerical Weather Prediction.
Securing ice cloud measurements
Ice clouds, covering more than 33% of Earth’s surface, have important effects on Earth’s climate and hydrological cycle by affecting precipitation, atmospheric structure, and cloud processes. Global measurements of ice cloud properties, including ice water path and ice particle size distribution, are therefore critically needed. With the latest scientific and technological developments for passive microwave sensors, measurements of ice clouds will close a gap in the measurement portfolio of the atmosphere.
WMO welcomes new Earth exploration satellite service (passive) allocations in the 239.2-242.2 GHz and 244.2-247.2 GHz essential for passive microwave remote sensing instruments to accommodate the requirements for ice cloud measurements.
Space-borne radar sounders operation
An important result for WMO is also a new Earth exploration satellite service (active) allocation in the 40-50 MHz that has been obtained after lengthy debates for the coverage of Antarctica and the North pole.
There is a strong interest among climate researchers in this frequency band for remote measurements of the Earth’s subsurface providing radar maps of subsurface scattering layers with the intent of locating water/ice/deposits and examining sub-ice glacial bed surfaces using active spaceborne sensors.
Protection of Earth exploration satellite observation
WMO also welcomes the addition of a footnote in the Radio Regulation regarding the protection of the Earth exploration satellite service (passive) allocations against the unwanted emission from non-geostationary satellite operating in the 37.5-38 GHz by imposing constraints in terms of altitude, unwanted emission of the effective isotropic radiated power and angles from nadir relative to the non-geostationary space station. Furthermore, this addition provides, for the first time in the Radio Regulation a protection of the cold calibration of Earth exploration satellite observation.
Safeguarding critical spectrum
ITU Radio Regulation No. 5.340 prohibits all radio emissions in specified frequency bands between 1400 MHz and 252 GHz.
Therefore, WMO welcomes the revision of the WRC Resolution 731 – a crucial resolution providing a real sanctuarization for the protection of frequency bands allocated to passive services above 71 GHz in the future.
WMO and ITU enjoy longstanding collaboration on meteorology data and digital technologies. Both are partners in the Early Warnings for All initiative spearheaded by UN Secretary-General António Guterres to ensure everyone on Earth is protected from climate hazards and disasters through life-saving alerts by the end of 2027.
Read about WMO’s position in ITU News special edition on Science services : Earth observation at the World Radiocommunication Conference
Watch ITU INTERVIEWS @ WRC-23: Natalia Donoho, Head, Space Systems and Utilization Division, WMO - YouTube
