1、1-Place des Nations Telephone +41 22 730 51 11 Telex 421 000 uit ch E-mail: itumailitu.intCH-1211 Geneva 20 Telefax Gr3: +41 22 733 72 56 Telegram ITU GENEVE www.itu.intSwitzerland Gr4: +41 22 730 65 00QUESTION ITU-R 201-3/3Radiometeorological data required for the planning of terrestrialand space
2、communication systems and space research application(1966-1970-1974-1978-1982-1990-1995-2000-2007)The ITU Radiocommunication Assembly,consideringa) that the characteristics of the tropospheric radio channel depend on a variety ofmeteorological parameters;b) that statistical predictions of radiopropa
3、gation effects are urgently required for planning anddesign of radiocommunication and remote sensing systems;c) that, for the development of such predictions, knowledge of all atmospheric parametersaffecting channel characteristics, their natural variability and their mutual dependence is needed;d)
4、that the quality of measured and suitably analysed radiometeorological data is one of thedeterminants of the ultimate reliability of propagation prediction methods that are based onmeteorological parameters;e) that an accurate knowledge of the clear-sky level on a satellite-to-ground link is importa
5、ntin developing the margin required to enable a telecommunications service to operate satisfactorilyunder adverse propagation conditions;f) that the clear-sky level on a satellite-to-ground link can fluctuate significantly bothdiurnally and seasonally due to solar heating and atmospheric effects;g)
6、that interest exists in extending the range of frequencies used for telecommunication andremote sensing purposes;h) that propagation conditions should be known as well as possible during the process ofbringing into service (BIS) of radio-relay equipment,decides that the following Question should be
7、studied1 What are the distributions of tropospheric refractivity, its gradients and their variability,both in space and time?2 What are the distributions of atmospheric constituents and particles, such as water vapourand other gases, clouds, fog, rain, hail, aerosols, sand, etc., both in space and t
8、ime?3 What is the magnitude of the variations in clear-sky level on a satellite-to-ground link thatcan occur on a diurnal and seasonal basis?- 2 -4 What model best describes the diurnal and seasonal variations in the clear-sky level on asatellite-to-ground link?5 How do the climatology and natural v
9、ariability of the rain process affect attenuation andinterference predictions, especially for tropical regions?6 What models best describe the relationship between atmospheric parameters and radiowavecharacteristics (amplitude, polarization, phase, angle of arrival, etc.)?7 What methods based on met
10、eorological information can be used in the statistical predictionof signal behaviour, especially for percentages of time from 0.1 to 10%, taking into account thecomposite effect of various atmospheric parameters?8 What procedures can be used to evaluate data quality, accuracy, statistical stability
11、andconfidence levels?9 What method can be used to forecast propagation conditions during consecutive periods of24 hours during any season anywhere in the world?NOTE 1 Priority will be given to studies relating to 3, 4, 5, 7 and 9.further decides1 that the results of the above studies should be included in one or more Recommendationsand/or Reports;2 that the above studies should be completed by 2010.Category: S2
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