氣象專業(yè)英語3課件

1、Unit Three: Meteorological Forecasts第三課：氣象預報New words:Warning 警報GMT （Greenwich Mean Time)格林威治時間 Upper-air 高空的Sounding 探測WWW(world weather watch) 世界天氣監(jiān)視網(wǎng)Code 電碼GTS（global telecommunication system) 全球電傳通信系統(tǒng)Strip 長帶 belt bandNOAA(National Oceanic and Atmospheric Administration) 諾阿衛(wèi)星（美國國家海洋大氣管理局）GOES (g

2、eostationary operational environment satellite) 地球靜止業(yè)務(wù)環(huán)境衛(wèi)星Multi-channel 多通道的Assemble 組裝，匯編 集合Short-range 短期的 Long-range 長期的 nowcasting 現(xiàn)時預報，臨近預報Extrapolation 外推 interpolation 內(nèi)插Divergence 輻散 barotropic正壓的Prognosis 預測 smooth 平滑 filter 濾波Geopotential 位勢的Prediction 預報 spectral 譜的 integrate 積分Nest 嵌套 pr

3、edictor 預報因子MSL (mean sea level)平均海平面 MOS (model output statistic) 模式輸出統(tǒng)計預報Thunderstorm 雷暴 hurricane 颶風Typhoon 臺風 Subgrid 次網(wǎng)格 Substructure n. 次級結(jié)構(gòu)次級結(jié)構(gòu)sub+ 亞；次級；下級亞；次級；下級 （構(gòu)詞法）（構(gòu)詞法）Subtropic 副熱帶，亞熱帶副熱帶，亞熱帶Unpredictable 不可預報的不可預報的 predictable 可預報的可預報的Predictability 可預報性可預報性Frame-work 框架框架 Topographic

4、地形的地形的 orographic Gust 陣風陣風 tornado （陸）龍卷（陸）龍卷Freezing 凍結(jié)的凍結(jié)的 Doppler(radar)多譜勒雷達多譜勒雷達Index(indices)指數(shù)指數(shù) shear 切變切變Downburst 下?lián)舯┝飨聯(lián)舯┝?Serve as 充當，作為P1National Meteorological Services perform a variety of activities in order to provide weather forecasts. The principal ones are data collection, the pr

5、eparation of basic analyses and prognostic charts of short-and long-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. 1. Data sources P2: The data required for foreca

6、sting and other services are provided by worldwide standard synoptic reports 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 sta

7、tions for severe weather . Under the World Weather Watch (WWW) program, synoptic reports are made at some 4,000 land stations and by 7,000 ships. There are about 700 stations making upper-air soundings (temperature, pressure, humidity, and, wind). These data are transmitted in code via teletype and

8、radio links in regional or national centers and into the high-speed Global Telecommunications System (GTS) connecting World Weather Centres in Melbourne, Moscow and Washington and eleven Regional Meteorological Centres for redistribution. Some 157 states and territories cooperate in this activity un

9、der the aegis of the World Meteorological Organization (WMO). P3:Meteorological 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. There are two general categories of weather satellite

10、: polar orbiters providing global coverage twice per 24 hours in orbital strips 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

11、(30-minute) coverage of almost one third of the earths surface in low middle latitudes. Information 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 whic

12、h receive radiation emitted from particular levels in the atmosphere. Additionally, satellites have a data collection system (DCS) that relays data on numerous environmental variations from ground platforms or ocean buoys to processing centres; GOES can also transmit processed satellite images in fa

13、csimile and the NOAA polar orbiters have an automatic picture transmission (APT) system that is utilized at 900 stations worldwide.2. Forecasting P4:Modern forecasting did not become possible until weather information could be rapidly collected, assembled and processed. The first development came in

14、 the middle of the last century with the invention of telegraphy, which permitted immediate analysis of weather data by the drawing of synoptic charts. These were first displayed in Britain at the Great Exhibition of 1851. Sequences of weather change were correlated with barometric pressure patterns

15、 both in space and time by such workers as Fitzroy and Abereroleby, but it was not until later that theoretival models of weather system were devisednotably the Bjerknes depression model. P5:Forecasts are usually referred to as short-range, medium (or extended) range and long-range. The first two ca

16、n for present purposes be considered together.Short-range forecastingP6: Forecasting 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. P7: Durin

17、g the first half of the century, short-range forecasts were based on synoptic principles, empirical rules and extrapolation of pressure changes.P8:Since 1955 routine forecasts have been based on numerical models. These predict the evolution of physical processes in the atmosphere by determinations o

18、f the conservation of mass, energy and momentum. The basic principle is that the rise or fall of surface pressure is related to mass convergence or divergence, respectively, in the overlying air column.P9:Forecast practices in the major national centres are basically similar. The forecasts are essen

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

20、grided 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. The NMC currently has two basic prediction models: a special model with (6 or) 12 layers (from the boundary layer into the upper str

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

22、mperature and wind velocity for standard pressure levels, 1000-500mb thickness, vertical motion and moisture content in the lower troposphere, and precipitation amounts.P10:Actual weather conditions are now commonly predicted using the Model Output Statistics(MOS) technique developed by the US Natio

23、nal Weather Service. Rather 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 num

24、erical models. Weather 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. These forecasts are d

25、istributed as facsimile maps and tables to weather offices for local use.P11:Errors in numerical forecast arise from several sources. One of the most serious is the limited accuracy of the initial analyses due to data deficiencies. The average over the oceans is sparse and only a quarter of the poss

26、ible 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. However, satellites-derived information and aircraft reports can help fill some gaps for the upper air. Another limitation is imposed by the horizontal and

27、 vertical resolution of the models and the need to parameterize subgrid processes such as cumulus convection. The 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 an unst

28、able air mass. Greater precision that the “showers and bright periods” or “scattered showers” of the forecast language is impossible with present techniques. The procedure for preparing a forecasting is becoming much less subjective, although in complex weather situations the skill of the experience

29、d forecaster still makes the technique almost as much as art as a science. Detailed 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 forecaster.Now

30、casting P12: Severe weather is typically short-lived(2 hr ) and, due to its mesoscale character(100km), it affects local/regional areas necessitating site-specific forecasts. Include in this category are thunderstorms, gust fronts, tornadoes, high winds especially along coasts, over lakes and mounta

31、ins, heavy snow and freezing precipitation. The development of radar networks, now instruments and high-speed communication links has provided a means of issuing warnings of such phenomena. Several countries have recently developed integrated satellite and radar systems to provide information on the

32、 horizontal and vertical extend of thunderstorms, for example. Such data are supplemented by networks of automatic weather stations (including buoys) that measure wind, temperature and humidity. In addition, for detailed boundary layer and lower troposphere data, there is now an array of vertical so

33、undersacoustic 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). Nowcasting tec

34、hniques use highly automated computers and image analysis systems to integrate data from a variety of sources rapidly. Interpretation of the data displays requires skilled personnel and/or extensive software to provide appropriate information. The prompt forecasting of wind shear and down-burst haza

35、rds at airports is one example of the importance of nowcasting procedures. P13: Overall, 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 manufacturing for 12-24 hour forecasts and in agriculture for 2-5 day forecasts. In terms of economic losses, the last category could benefit the most from more rel