1、 Rec. ITU-R RS.1165-2 1 RECOMMENDATION ITU-R RS.1165-2 Technical characteristics and performance criteria for systems in the meteorological aids service in the 403 MHz and 1 680 MHz bands (1995-1997-2006) Scope This Recommendation gives the technical characteristics and performance criteria for syst
2、ems in the meteorological aids service in the 403 MHz and 1 680 MHz bands. All the various metaids systems are covered: radiosondes, dropsondes and rocketsondes. The ITU Radiocommunication Assembly, considering a) that upper-air meteorological measurements carried out by radiosondes are an essential
3、 element of the World Weather Watch Programme of the World Meteorological Organization (WMO); b) that many defence services deploy radiosonde systems in order to support a variety of operations, independent of the World Weather Watch Programme; c) that many radiosonde systems are used for local and
4、regional monitoring of atmospheric pollution conditions and also for tracking the trajectories of hazardous discharges from natural or man-made disasters; d) that radiosonde systems operating in the meteorological aids (MetAids) service have unique radiocommunication requirements; e) that radiosonde
5、, dropsonde, and rocketsonde systems under MetAids service mainly operate in the bands 400.15-406 MHz (called the 403 MHz band) and 1 668.4-1 700 MHz (called the 1 680 MHz band) with limitations as per the provision No. 5.379E of the Radio Regulations (RR); f) that radiosondes in the MetAids service
6、 are flown on balloons and rockets and may operate with stations located on land or ships; g) that other types of radiosondes in the MetAids service are dropped from aircraft and operate with stations located on aircraft; h) that performance objectives for transmissions to and from radiosondes must
7、be consistent with the attendant functional requirements and with the performance limitations associated with the systems and frequency bands in which the requirements will be fulfilled; j) that performance objectives for representative systems operating in the MetAids service are intended to provid
8、e guidelines for the development of actual systems that must operate in a frequency sharing environment; k) that performance objectives for particular systems may be determined using the methodology similar to that described in Recommendation ITU-R SA.1021; 2 Rec. ITU-R RS.1165-2 l) that performance
9、 objectives are a prerequisite for the determination of interference criteria; m) that Recommendation ITU-R RS.1263 provides the interference criteria for systems in the meteorological aids service operating in the 403 MHz and 1 680 MHz bands, recommends 1 that the technical and operational characte
10、ristics in Annex 1 should be considered as typical for meteorological aids in the 403 and 1 680 MHz bands; 2 that the performance criteria specified in Table 3 should be considered when developing interference criteria and conducting sharing studies with other services. Annex 1 1 Introduction 1.1 Da
11、ily meteorological operations Meteorological aids1are mainly used for in situ upper air measurements of meteorological variables (pressure, temperature, relative humidity, windspeed and direction) in the atmosphere up to an altitude of 36 km. The measurements are vital to national weather forecastin
12、g capability (and hence severe weather warning services for the public involving protection of life and property). The meteorological aids and associated tracking systems provide simultaneous measurements of the vertical structure of temperature, relative humidity and wind speed and direction over t
13、he full height range required. The variation of these meteorological variables in the vertical contains the majority of the critical information for weather forecasting. The MetAids systems are the only meteorological observing systems able to regularly provide the vertical resolution that meteorolo
14、gists need for all four variables. Identification of the heights where sudden changes in a variable occur is vital. Thus, it is essential that continuity of reliable measurements is sustained throughout the ascent of the radiosonde. The MetAids observations are produced by radiosondes carried by asc
15、ending balloons launched from land stations or ships, dropsondes deployed from aircraft and carried by a parachute, and rocketsondes lifted into the atmosphere by rocket and descend under a parachute during data collection. Radiosonde observations are carried out routinely by almost all countries, t
16、wo to four times a day. The observation data are then circulated immediately to all other countries within a few hours via the WMO Global Telecommunications System (GTS). The observing systems and data dissemination are all organized under the framework of the World Weather Watch Programme of WMO. 1
17、This Recommendation addresses radiosondes, dropsondes, and rocketsondes operated in the meteorological aids (MetAids) service. The term MetAids is used when the discussion applies to all three types of systems. The specific system name (radiosonde, dropsonde and rocketsonde) is used when the discuss
18、ion applies to one or two of the specific types of systems. Rec. ITU-R RS.1165-2 3 The radiosonde network provides the primary global source of real-time in situ measurements. WMO Regulations (Manual on the Global Data-Processing System (GDPS) require that radiosonde measurements should be made and
19、circulated to all GDPS centres worldwide at national, regional and global levels for numerical weather prediction. The observation stations are required, worldwide, at a horizontal spacing of less than or equal to 250 km, during the first decade of the twenty-first century, with a frequency of obser
20、vation of from one to four times per day. However, the numerical weather prediction models for small scale meteorological phenomena (e.g. thunderstorm, local winds, tornadoes) and environmental emergencies will actually require local upper air observations every one to three hours at a horizontal re
21、solution from 50 to 100 km. Observations are to be provided from a variety of observing systems, chosen according to the needs of the national administration, including MetAids measurements, wind profiler radar measurements or satellite measurements. The radiosonde observations are essential to main
22、tain stability in the WMO Global Observing System (GOS). Remotely sensed measurements from satellites do not have the vertical resolution available from radiosondes. Successful derivation of vertical temperature structure from these satellite measurements usually requires a computation initialized e
23、ither directly from radiosonde statistics or from the numerical weather forecast itself. In the latter case, the radiosonde measurements ensure that the vertical structure in these forecasts remains accurate and stable with time. In addition, the radiosonde measurements are used to calibrate satelli
24、te observations by a variety of techniques. Radiosonde observations are thus seen to remain absolutely necessary for meteorological operations for the foreseeable future. 1.2 Monitoring climate change Large worldwide changes have occurred in atmospheric temperature and ozone in the last 20 years, wi
25、th many of the largest changes taking place at heights between 12 and 30 km above the surface of the Earth. The changes are large enough to cause concern about safety of future public health. Routine daily radiosonde observations to heights above 30 km identify the distribution in the vertical of th
26、e changes that occur and hence allow the causes of the changes to be evaluated. Ozonesonde measurements to similar heights determine the vertical distribution of the ozone depletion that now appears to be occurring in both Southern and Northern Hemisphere winter and spring. Many countries fly ozones
27、ondes at least three times per week during these seasons to monitor developments. Successful sampling of climate change requires the use of radiosondes with established systematic error characteristics. The requirement for continuity in the time series of upper air measurements worldwide means that
28、new radiosonde designs are only introduced into operation after several years of intensive testing, that occurs both in the laboratory and in the free atmosphere. 1.3 Other users Other MetAids systems may be deployed independently of the main civilian meteorological organization by national research
29、 institutes and other users. Specific investigations will include environmental pollution, hydrology, radioactivity in the free atmosphere, significant weather phenomena (e.g. winter storms, hurricanes, thunderstorms, etc.) and investigation of a range of physical and chemical properties of the atmo
30、sphere. This use is not decreasing with time, since with modern automation it is now much easier to successfully operate mobile systems and shipboard systems without highly skilled operators and a large amount of supporting equipment. MetAids operations have to accommodate these users, and this expa
31、nds the radio-frequency spectrum required for MetAids operations. This is particularly critical when launch sites of these other users are within 150 km of the meteorological organization launch sites. 4 Rec. ITU-R RS.1165-2 2 Characteristics of radiosonde operation While many radiosonde operations
32、are normally conducted on a specific schedule, operations can be conducted at any time of the day or night in response to specific operational requirements, atmospheric conditions, or testing requirements. Synoptic radiosonde observations are carried out worldwide to provide the observations necessa
33、ry for daily weather forecasting. The standard observations are nominally performed at 0000 and 1200 UTC, but the actual launch times vary according to national practice and in some cases will be at least three-quarters of an hour earlier than the nominal time. The launch may also be up to two hours
34、 later than nominal if there are problems with preparation of the radiosonde prior to flight, if local air traffic regulations limit launch times or if there is a malfunction during the initial flight. Intermediate observations at 0600 and 1800 UTC are also performed routinely in several countries.
35、Additional radiosondes and dropsondes are launched periodically by synoptic operators, often from temporary sites using mobile systems, in response to abnormal weather or requirements for testing. Non-synoptic flights are scheduled to meet operational requirements. The radiosonde networks are implem
36、ented and operated by national meteorological services in compliance with recommended practices and procedures internationally agreed upon by WMO. The current number of radiosonde stations reporting regularly is about 900. About 800 000 radiosondes are routinely launched in a year in association wit
37、h the WMO network and it is estimated that about another 400 000 radiosondes are used for defence use and specialized applications. The current level of radiosonde use does not adequately meet meteorological requirements due to operational costs. 3 Radio-frequency spectrum used in operations for WMO
38、 reporting 3.1 Results from WMO survey Table 1 presents estimates of the radio frequency use at synoptic radiosonde stations reporting information daily for WMO meteorological data exchange. This information is based on the WMO Catalogue of Radiosondes and Upperwind Systems in use by Members. The su
39、rvey results are grouped into regions to illustrate the variation in use worldwide. More detailed information is available from the WMO Catalogue of Radiosondes and Upperwind Systems in use by Members. Proposals for band segmentation would have to take account of the fact that bands internationally
40、allocated to MetAids on a primary basis are not available to this service in all countries. For instance, in Australia, at least half of the 403 MHz frequency band is currently not available for MetAids operations. Use of the two main frequency bands allocated to MetAids (403 and 1 680 MHz bands) va
41、ries widely in different parts of the world. Systems operating in the 1 680 MHz band are operated primarily in the United States of America, Japan and China. These systems are providing synoptic data to the WMO GTS. Within these countries other users primarily use the 403 MHz band for non-synoptic o
42、perations. Within Europe, the 403 MHz band is used heavily to support synoptic radiosonde operations. Russia and some countries with cooperating arrangements use frequencies around 1 780 MHz for radiosonde operations. Countries using 1 780 MHz are expected to transfer their operations to one of the
43、two main bands in order to take advantage of commercially available equipment. Rec. ITU-R RS.1165-2 5 TABLE 1 Summary of radio frequency use for radiosondes for daily synoptic operations Region Total Number of sites Number of sites using 400 MHz Number of sites using 1 680 MHz Number of sites using
44、1 780 MHz(1)Europe and Western Russia 184 122 12 50 Asia and Eastern Russia 370 139 127 104 Africa 74 65 9 0 North America 166 55 109 2 South America and Antarctica 74 63 7 4 Australia and Oceania 100 73 27 0 Ship systems 36 36 0 0 Overall 1004 553 291 160 (1)The 1 780 MHz band (1 774-1 790 MHz) is
45、used in a few countries around the world but is not allocated to the meteorological aids service in the RR. 3.2 Radio-frequency spectrum used in Western and Northern Europe In Western and Northern European areas the radiosonde network is dense, with stations operated for routine meteorological opera
46、tions, environmental monitoring and a variety of defence operations. Most of the radiosondes are operating in the 403 MHz band. The majority of these radiosondes are currently analogue, but it is expected that they will evolve to digital communications in the future. Harmonized European standards co
47、vering the essential requirements for spectral mask and transmission power have been developed for all digital radiosondes used in Europe. There is no harmonized standard for analogue radiosondes and their use is based on national approval. 3.3 Radio-frequency spectrum used in North and South Americ
48、a The civilian weather service in the United States of America is currently the main user of the 1 680 MHz band. Other US users utilize the 403 MHz band. Though an allocation exists covering the range 1 668.4-1 700 MHz, the civilian weather service operations are concentrated in the 1 675-1 683 MHz
49、band to avoid incompatibility with other services in the 1 668.4-1 675 MHz and 1 683-1 700 MHz bands. The civilian weather service does operate several 403 MHz band systems in locations where interference to a main MetSat earth station is a problem or where installation of a large parabolic tracking antenna is impractical. The use of radiosondes in the 403 MHz band in the United States of America has recently been surveyed and confirms that large numbers of systems are deployed by the non-synoptic users. At least another 40 systems are used by universities or other United States agencies. Som
