专业英语3-new

1、Unit III: Meteorological Forecasts第三课：气象预报New Wordsvwarning 警报vGMT (Greenwich Mean Time) 格林威治时间 vupper-air 高空的vsounding 探测vWWW(World Weather Watch) 世界天气监视网vcode 电码vGTS(Global Telecommunication System) 全球电传通信系统voperationally 业务上vstrip 长带 belt bandvNOAA(National Oceanic and Atmospheric Administration)

2、 诺阿卫星（美国国家海洋大气管理局）vTIROS(Television and InfRared Observing Satellite) 泰罗斯卫星（电视红外业务卫星）vgeosynchronous 地球同步的vgeostationary 相对于地球静止的vGOES (Geostationary Operational Environment Satellite) 地球静止业务环境卫星vmulti-channel 多通道的vrelay 中继vbuoy 浮标站vassemble 组装，汇编 集合vbarometric 气压的vshort-range 短期的 long-range 长期的 vex

3、tended range 延伸期的vnowcasting 现时预报，临近预报vextrapolation 外推 interpolation 内插vforecaster 预报员vconservation 保守vdivergence 辐散 vprognosis 预测 prognostic 预报的vsmooth 平滑 filter 滤波vgeopotential 位势的vprediction 预报 vspectral 谱的 vintegrate 积分vnest 嵌套 vseveral-fold 翻几番vMSL (Mean Sea Level) 平均海平面 vMOS (Model Output Sta

4、tistics) 模式输出统计vregression 回归vpredictor 预报因子vthunderstorm 雷暴 hurricane typhoonvparameterize 参数化vsubgrid 次网格 substructure 次级结构 sub+ 亚；次级；下级 （构词法） subtropic 副热带，亚热带vunpredictable 不可预报的 predictable 可预报的 predictability 可预报性vframe-work 框架 vtopographic 地形的 orographic vsite-specific 定点的vgust 阵风 vtornado （陆

5、）龙卷vfreezing 冻结的 vDoppler(radar) 多谱勒雷达vindex(indices)指数 vshear 切变vdownburst 下击暴流 vNational Meteorological Services perform a variety of activities in order to provide weather forecasts. vThe principal ones are data collection, the preparation of basic analyses and prognostic charts of short-and long

6、-term forecasts for the public as well as special services for aviation, shipping , agricultural and other commercial and industrial users, and the issuance of severe weather warnings.Data sources vThe data required for forecasting and other services are provided by worldwide standard synoptic repor

7、ts at 00, 06, 12, and 18 GMT, similar observations made hourly, particularly in support of national aviation requirements, upper-air soundings (at 00 and 12 GMT), satellite data and other specialized networks such as radar stations for severe weather.vUnder the World Weather Watch (WWW) program, syn

8、optic reports are made at some 4,000 land stations and by 7,000 ships. vThere are about 700 stations making upper-air soundings (temperature, pressure, humidity, and, wind). vThese data are transmitted in code via teletype and radio links in regional or national centers and into the high-speed Globa

9、l Telecommunications System (GTS) connecting World Weather Centers in Melbourne, Moscow and Washington and eleven Regional Meteorological Centers for redistribution. vSome 157 states and territories cooperate in this activity under the aegis of the World Meteorological Organization (WMO). vMeteorolo

10、gical information has been collected operationally by satellites of the United States and USSR since 1965 and, more recently, by the European Space Agency, India and Japan.vThere are two general categories of weather satellite: polar orbiters providing global coverage twice per 24 hours in orbital s

11、trips over the poles (such as the Unites States NOAA and TIROS series, and the USSRs Meteor) and geosynchronous satellites(such as the Geostationary Operational Environmental Satellites (GOES) and Metosat ), giving repetitive(30-minute) coverage of almost one third of the earths surface in low middl

12、e latitudes. vInformation on the atmosphere is collected as digital data or direct readout visible and infrared images of cloud cover and sea-surface temperature, but also includes global temperature and moisture profiles through the atmosphere obtained from multi-channel infrared and microwave sens

13、ors which receive radiation emitted from particular levels in the atmosphere.vAdditionally, satellites have a data collection system (DCS) that relays data on numerous environmental variations from ground platforms or ocean buoys to processing centers; vGOES can also transmit processed satellite ima

14、ges in facsimile and the NOAA polar orbiters have an automatic picture transmission (APT) system that is utilized at 900 stations worldwide.Forecasting vModern forecasting did not become possible until weather information could be rapidly collected, assembled and processed. vThe first development ca

15、me in the middle of the last century with the invention of telegraphy, which permitted immediate analysis of weather data by the drawing of synoptic charts. vThese were first displayed in Britain at the Great Exhibition of 1851. vSequences of weather change were correlated with barometric pressure p

16、atterns both in space and time by such workers as Fitzroy and Abereroleby, but it was not until later that theoretical models of weather system were devisednotably the Bjerknes depression model. vForecasts are usually referred to as short-range, medium (or extended) range and long-range. The first t

17、wo can for present purposes be considered together.Short-range forecastingvForecasting procedures developed up to the 1950s were based on synoptic principles but, since the 1960s, practices have been revolutionized by numerical forecasting models and the adoption of “nowcasting” techniques.vDuring t

18、he first half of the century, short-range forecasts were based on synoptic principles, empirical rules and extrapolation of pressure changes.vSince 1955 routine forecasts have been based on numerical models. These predict the evolution of physical processes in the atmosphere by determinations of the

19、 conservation of mass, energy and momentum.vThe basic principle is that the rise or fall of surface pressure is related to mass convergence or divergence, respectively, in the overlying air column.vForecast practices in the major national centers are basically similar. vThe forecasts are essentially

20、 derived from twice-daily (00 and 12 GMT) prognoses of atmospheric circulation. vSince most techniques are now largely automated, the analyses of synoptic fields are based on the previous 12-hour forecast maps as a first guess. vThree different interpolation methods are used to obtain smoothed, grid

21、ded data on temperature, moisture, wind and geopotential height for the surface at standard pressure levels (850,700, 500, 400, 300, 250, 200 and 100 mb) over the globe. vThe NMC currently has two basic prediction models: a special model with (6 or) 12 layers (from the boundary layer into the upper

22、stratosphere), which is integrated for up to 10 days, and a regionally applicable nested grid model with finer horizontal resolution. vIt should be noted that typically the computer time required increases several-fold when the grid spacing is halved. vThe essential forecast products are MSL pressur

23、e, temperature and wind velocity for standard pressure levels, 1000-500mb thickness, vertical motion and moisture content in the lower troposphere, and precipitation amounts.vActual weather conditions are now commonly predicted using the Model Output Statistics(MOS) technique developed by the US Nat

24、ional Weather Service. vRather than relating weather variable to the predicted pressure/height patterns and taking account of frontal models, for example, a series of regression equations are developed for specific locations between the variable of interest and up to 10 predictors calculated by the

25、numerical models. vWeather elements so predicted for numerous locations include daily maximum/minimum temperature, 12-hour probability of precipitation occurrence, and precipitation amount, probability of frozen precipitation, thunderstorm occurrence, cloud cover and surface winds. vThese forecasts

26、are distributed as facsimile maps and tables to weather offices for local use.vErrors in numerical forecast arise from several sources. One of the most serious is the limited accuracy of the initial analyses due to data deficiencies. vThe average over the oceans is sparse and only a quarter of the p

27、ossible ship reports may be received within 12 hours; even over the land more than one-third of the synoptic reports may be delayed beyond 6 hours. vHowever, satellites-derived information and aircraft reports can help fill some gaps for the upper air. vAnother limitation is imposed by the horizonta

28、l and vertical resolution of the models and the need to parameterize subgrid processes such as cumulus convection. vThe small-scale nature of the turbulent motion of the atmosphere means that some weather phenomena are basically unpredictable, for example, the specific locations of shower cells in a

29、n unstable air mass. vGreater precision that the “showers and bright periods” or “scattered showers” of the forecast language is impossible with present techniques.vThe procedure for preparing a forecasting is becoming much less subjective, although in complex weather situations the skill of the exp

30、erienced forecaster still makes the technique almost as much as art as a science. vDetailed regional or local predictions can only be made within the framework of the general forecast situation for the country and demand thorough knowledge of possible topographic or other local effects by the foreca

31、ster.NowcastingvSevere weather is typically short-lived(2 hr ) and, due to its mesoscale character(100km), it affects local/regional areas necessitating site-specific forecasts. vInclude in this category are thunderstorms, gust fronts, tornadoes, high winds especially along coasts, over lakes and mo

32、untains, heavy snow and freezing precipitation. vThe development of radar networks, now instruments and high-speed communication links has provided a means of issuing warnings of such phenomena. vSeveral countries have recently developed integrated satellite and radar systems to provide information

33、on the horizontal and vertical extend of thunderstorms, for example. vSuch data are supplemented by networks of automatic weather stations (including buoys) that measure wind, temperature and humidity. vIn addition, for detailed boundary layer and lower troposphere data, there is now an array of ver

34、tical soundersacoustic sounders (measuring wind speed and direction from echoes created by thermal eddies), specialized (Doppler) radar measuring winds in clear air by returns either from insects(3.5 cm wavelength radar) or from variations in the airs refractive index(10 cm wavelength radar). vNowca

35、sting techniques use highly automated computers and image analysis systems to integrate data from a variety of sources rapidly. vInterpretation of the data displays requires skilled personnel and/or extensive software to provide appropriate information. vThe prompt forecasting of wind shear and down

36、-burst hazards at airports is one example of the importance of nowcasting procedures. vOverall, the greatest benefits from improved forecasting can be expected in aviation, construction and the electric power industry for forecast less than 6 hours ahead, in transpiration, construction and manufactu

37、ring for 12-24 hour forecasts and in agriculture for 2-5 day forecasts. vIn terms of economic losses, the last category could benefit the most from more reliable and precise forecasts.Long-range forecastingvThe methods discussed above are unsuitable for predicting the probable trend of the weather for periods of a month o