WMO Position on the WRC-23 Agenda
WMO Workshop on the WRC-23 Agenda
WMO Position on the WRC-23 Agenda
Continuation of SST measurements (consequential to WRC-23 A.I. 1.2)
Sea Surface Temperature (SST) is a vital component of the climate system as it exerts a major influence on the exchanges of energy, momentum and gases between the ocean and atmosphere. SST is one of the main drivers of the ocean circulation, which is key for numerical weather and ocean prediction models.
It is recognized that the 6/7 GHz frequency range is unique for passive ocean remote sensing since it corresponds to the peak sensitivity to SST. Several passive microwave sensors (e.g., AMSR2 onboard GCOM-W) operate and plan to operate in this frequency range, and are the only SST measurements that can see through clouds.
The Radio Regulations (RR) acknowledge the usage of the bands 6 425-7 075 MHz and 7 075-7 250 MHz by the Earth exploration-satellite service (passive) in RR No 5.458 that states that administrations should bear in mind the needs of EESS (passive) sensors in their future planning of that frequency range. However, this footnote is not considered as an allocation to EESS (passive) and does not then provide any protection to SST measurements carried out in these bands.
Under the WRC-23 A.I. 1.2, these two frequency bands are proposed for International Mobile Telecommunication (IMT) identification. ITU-R studies clearly demonstrate that, as a consequence of this WRC-23 agenda item, SST measurements will be severely constrained by future massive deployment of communication systems in this frequency range. To mitigate this threat, WMO through its ET-RFC, identified the potential frequency bands that could be used in combination with the 6/7 GHz range to allow the retrieval of SST measurements assuming that the measurements in the 6/7 GHz frequency range become significantly degraded.
Therefore, in order to ensure continuity of vitally important SST measurements on a long-term basis, WMO proposes the following action to be taken at WRC-23:
- to consider new primary EESS (passive) allocations in the 4.2–4.4 GHz and 8.4–8.5 GHz frequency bands in which SST measurements can also be performed.
Recognition of Space Weather (WRC-23 A.I. 9.1a)
Space weather observations from ground-based and space-based systems are becoming more and more important, in particular for the detection of solar activity events that has the potential to cause mass disruption on Earth. The effects of space weather can range from damage to satellites (for instance, in February 2022 many satellites were lost after they were hit by a geomagnetic storm a day after launch) to disruption of power grids on Earth during geomagnetic storms, radio black-out on trans-polar aircraft routes, or disturbance of satellite positioning systems.
Considering that space weather observations are critical for forecasting and providing alerts of hazardous space weather events, it is surprising to see that the Radio Regulations currently do not contain any recognition or provisions related to space weather observations using radio spectrum.
Therefore, in order to ensure protection of space weather sensor operations in the future, WMO advocates for the following two-step approach to be taken at WRC-23:
Step 1. Define space weather in the context of the Radio Regulations and associate space weather with the appropriate “radiocommunication service” under which space weather systems may operate (namely meteorological aids service (space weather)). Without this first step completed, any attempt to start sharing studies would be meaningless since ITU-R studies are performed between radiocommunication services.
Step 2. Develop a new WRC-27 agenda item on space weather, which will identify the frequency bands used by operational space weather sensors/stations that require protection.