Introduction

Access to radiofrequency spectrum is critical to the operation of global meteorological and hydrological infrastructure, underpinning the service delivery of all WMO Members. Satellites, weather radars, radiosondes, hydrological observing systems and drifting buoys and other ocean-based platforms - all require radio or microwave transmissions to operate. In particular, microwave observations of the atmosphere from satellites, operating in all weather conditions and providing global coverage several times per day, have been integral to the improved accuracy of forecasts and the extended warning times for severe events that we have available to us today.

Availability of radio-frequency bands free from harmful interference (from both in-band and out-of-band interferers) is a key requirement for the development of all Earth observation systems.

Frequency allocations are part of the International Radio Regulations that are developed and negotiated among national telecommunications authorities and eventually agreed at World Radiocommunication Conferences, which are held every three or four years to review, and, if necessary, revise the Radio Regulations, the international treaty governing the use of the radio-frequency spectrum by various systems, including for Earth observation applications. Preparations for the World Radiocommunication Conferences involve detailed studies and assessments by the various communities involved.

For the meteorological community, these issues are addressed within WMO by the Expert Team on Radio-Frequency Coordination (ET-RFC). Within Europe, more than 20 National Meteorological Services and other relevant organizations have established the EUMETFREQ programme in order to coordinate their frequency protection activities. Frequency management and protection are particularly important for satellite activities in general, and Space Agencies have established the Space Frequency Coordination Group (SFCG) to coordinate their activities in this respect.