WMO highlights importance of radio frequencies for earth observations

Geneva (WMO) – Weather forecasts, disaster warnings and climate monitoring are all critically dependent on radio frequency bands which are used around the clock by meteorological services. Increasing pressure on the use of radio spectrum from wireless technology and other applications could hamper Earth observations and efforts to understand and predict climate change.

These are some key points of a submission by the World Meteorological Organization (WMO) to the World Radiocommunication Conference taking place in Geneva 23 January to 17 February 2012. The conference is mandated to review and revise the Radio Regulations, the international treaty governing the use of radio-frequency spectrum.

National Meteorological and Hydrological Services are responsible for providing timely warnings of impending natural and environmental disasters, climate predictions and assessments of global water resources.

These services protect lives and livelihoods and promote sustainable economic development.

They are dependent on observations of our Earth, atmosphere and oceans. Radio frequencies are critical both for collecting this observational data and disseminating it to society.

Successive World Radiocommunication Conferences have taken into account the needs of the meteorological community to ensure the availability and protection of scarce and valuable radio-frequency bands for making and exchanging these observations. The forthcoming conference is urged to uphold this commitment.

Pressure from new applications

“Sound management of allocated frequency bands is vital to the quality and accuracy of weather and weather-related predictions,” said WMO Secretary-General Michel Jarraud.

“If some of the frequency bands currently allocated for meteorological purposes were to be used by other radio applications that are incompatible with meteorological use, then these bands could be rendered unusable for weather, climate and/or disaster prediction systems. This would make corresponding forecasts extremely difficult and sometimes impossible,” he said.

“Given that weather, climate and water-related disasters represent more than 90% of natural disasters, radio frequencies are essential components of multi-hazard early warning systems,” said Mr Jarraud.

The development of new, mass-market and added-value radio applications and wireless technology is putting increasing pressure on the frequency bands used for meteorological purposes. This presents the potential risk of limiting meteorological applications in future.

The World Meteorological Congress in June 2011 allocated additional funding to support WMO’s radio frequency coordination activities in view of their fundamental importance.

Global Observing System

The WMO Integrated Global Observing System includes the World Weather Watch, the Global Atmosphere Watch and the World Hydrological Cycle Observing System. These make use of a number of different radio applications and services which require reliable access to radio frequencies ranging from few kilohertz (KHz) to terahertz (THz).

Space-borne sensing of the Earth’s surface and atmosphere has an essential and increasing importance in operational and research meteorology, in particular for mitigating the impact of weather and climate-related disasters, and in the scientific understanding, monitoring and prediction of climate change and its impacts.

The impressive progress made in the recent years in weather and climate analysis and forecasts, including warnings for dangerous weather phenomena (heat waves, heavy rain, storms, cyclones) that affect all populations and economies, is to a great extent attributable to space-borne observations and their assimilation in numerical models.

These services may be affected by World Radiocommunication Conference decisions.

Space-borne passive sensing for meteorological applications is performed in bands allocated to the Earth exploration-satellite (passive) and meteorological satellite services. Passive sensing requires the measurement of naturally-occurring radiations, usually of very low power levels, which contain essential information on the physical process under investigation.

The relevant frequency bands are determined by fixed physical properties (molecular resonance) that cannot be changed or ignored. These physical properties cannot be duplicated in other bands.

Even low levels of interference received by a passive sensor may degrade its data.

For passive sensing bands shared with active services, the situation tends to be more and more critical with the increased density of terrestrial active devices, and serious cases of interference are already reported.

Space-borne active sensing, performed in particular by altimeters and scatterometers for ocean and ice studies, and by rain and cloud radars, provides important information on the state of the ocean and land surfaces and atmospheric phenomena.

Surface-based meteorological radars and wind-profiler radars are important instruments, providing essential measurements of precipitation and other weather elements. This is especially useful for nowcasting, (the detailed description of weather for 0 to 6 hours) of rapidly evolving conditions.

Meteorological radar networks often represent the last line of defence in a disaster warning strategy against loss of life and property in flash flood or severe storm events.

Meteorological aids systems, mainly radiosondes, are the main source of atmospheric in situ measurements with high vertical resolution (temperature, relative humidity and wind speed) to provide real time vertical atmospheric profiles that are and will remain essential for operational meteorology, including weather analysis prediction and warnings, as well as for climate monitoring. In addition, these in situ measurements are essential for calibrating space-borne remote sensing, in particular passive.

Also of great importance is the availability of sufficient and well-protected Earth exploration and meteorological-satellite services frequency spectrum for telemetry/telecommand as well as for satellite downlink of the collected data.

Fixed-satellite service systems, through commercial payloads in the C-band ((3400-4200 MHz), L-Band frequencies of 1695-1710 MHz and the Ku Band (10700-11700 MHz), are used globally to disseminate weather, water and climate related information, including disaster warnings to meteorological agencies and user communities. A large part of the population, in particular in developing countries, is heavily dependent on the use of C-Band satellites, for instance in areas where heavy rain in tropical and equatorial zones makes the use of any other telecommunication support impractical.

Notes to Editors:

The Sixteen World Meteorological Congress (Geneva, May 2011) “…agreed that the protection of frequencies used for meteorological purposes is of direct and vital interest to the international meteorological community and reiterated its full support for radio-frequency activities. It urged the pursuance of, in an organized manner, the continuous review of regulatory and technical matters related to radio-frequencies for operational and research meteorological and

For more information please contact:

Clare Nullis, Press Officer, Communications and Public Affairs,
Tel: +(41 22) 730 8478; 41-79) 7091397 (cell)
e mail: cnullis(at)wmo.int related environmental activities.