<div class="eI0">
  <div class="eI1">Model:</div>
  <div class="eI2"><h2>GEFS: Global Ensemble weather forecast from the "American Weatherservice "</h2></div>
 </div>
 <div class="eI0">
  <div class="eI1">Zaktualizowano:</div>
  <div class="eI2">2 times per day, from 10:00 and 23:00 UTC</div>
 </div>
 <div class="eI0">
  <div class="eI1">Czas uniwersalny:</div>
  <div class="eI2">12:00 UTC = 13:00 CET</div>
 </div>
 <div class="eI0">
  <div class="eI1">Rozdzielczo&#347;&#263;:</div>
  <div class="eI2">1.0&deg; x 1.0&deg;</div>
 </div>
 <div class="eI0">
  <div class="eI1">parametr:</div>
 </div>
 <div class="eI0">
  <div class="eI1">Opis:</div>
  <div class="eI2">
    
  </div>
 </div>
 <div class="eI0">
  <div class="eI1">Ensemble forecasting:</div>
  <div class="eI2">
is a numerical prediction method that is used to attempt to generate a representative sample of the possible future states of a dynamical system. Ensemble forecasting is a form of Monte Carlo analysis: multiple numerical predictions are conducted using slightly different initial conditions that are all plausible given the past and current set of observations, or measurements. Sometimes the ensemble of forecasts may use different forecast models for different members, or different formulations of a forecast model. The multiple simulations are conducted to account for the two sources of uncertainty in weather forecast models: (1) the errors introduced by chaos or sensitive dependence on the initial conditions; and (2) errors introduced because of imperfections in the model, such as the finite grid spacings.<br>
Considering the problem of numerical weather prediction, ensemble predictions are now commonly made at most of the major operational weather prediction facilities worldwide, including the National Centers for Environmental Prediction (US), the European Centre for Medium-Range Weather Forecasts (ECMWF), the United Kingdom Met Office, Meteo France, Environment Canada, the Japanese Meteorological Agency, the Bureau of Meteorology (Australia), the China Meteorological Administration, the Korea Meteorological Administration, and CPTEC (Brazil). Experimental ensemble forecasts are made at a number of universities, such as the University of Washington, and ensemble forecasts in the US are also generated by the US Navy and Air Force.<br>
Ideally, the relative frequency of events from the ensemble could be used directly to estimate the probability of a given weather event. For example, if 30 of 50 members indicated greater than 1 cm rainfall during the next 24 h, the probability of exceeding 1 cm could be estimated to be 60 percent. The forecast would be considered reliable if, considering all the situations in the past when a 60 percent probability was forecast, on 60 percent of those occasions did the rainfall actually exceed 1 cm. This is known as reliability or calibration. In practice, the probabilities generated from operational weather ensemble forecasts are not highly reliable, though with a set of past forecasts (reforecasts or hindcasts) and observations, the probability estimates from the ensemble can be adjusted to ensure greater reliability. Another desirable property of ensemble forecasts is sharpness. Provided that the ensemble is reliable, the more an ensemble forecast deviates from the climatological event frequency and issues 0 percent or 100 percent forecasts of an event, the more useful the forecast will be. However, sharp forecasts that are unaccompanied by high reliability will generally not be useful. Forecasts at long leads will inevitably not be particularly sharp, for the inevitable (albeit usually small) errors in the initial condition will grow with increasing forecast lead until the expected difference between two model states is as large as the difference between two random states from the forecast model's climatology.<br>
There are various ways of viewing the data such as spaghetti plots, ensemble means or Postage Stamps where a number of different results from the models run can be compared.<br>
<br>Wikipedia, Ensemble forecasting, <a href="http://en.wikipedia.org/wiki/Ensemble_forecasting" target="_blank">http://en.wikipedia.org/wiki/Ensemble_forecasting</a> (optional description here) (as of Feb. 9, 2010, 20:30 UTC).<br>
   </div>
  </div>
 <div class="eI0">
  <div class="eI1">NWP:</div>
  <div class="eI2">Numeryczna prognoza pogody - ocena stanu atmosfery w przysz&#322;o&#347;ci na podstawie znajomo&#347;ci warunk&oacute;w pocz&#261;tkowych oraz si&#322; dzia&#322;aj&#261;cych na powietrze. Numeryczna prognoza oparta jest na rozwi&#261;zaniu r&oacute;wna&#324; ruchu powietrza za pomoc&#261; ich dyskretyzacji i wykorzystaniu do oblicze&#324; maszyn matematycznych.<br>
Pocz&#261;tkowy stan atmosfery wyznacza si&#281; na podstawie jednoczesnych pomiar&oacute;w na ca&#322;ym globie ziemskim. R&oacute;wnania ruchu cz&#261;stek powietrza wprowadza si&#281; zak&#322;adaj&#261;c, &#380;e powietrze jest ciecz&#261;. R&oacute;wna&#324; tych nie mo&#380;na rozwi&#261;zać w prosty spos&oacute;b. Kluczowym uproszczeniem, wymagaj&#261;cym jednak zastosowania komputer&oacute;w, jest za&#322;o&#380;enie, &#380;e atmosfer&#281; mo&#380;na w przybli&#380;eniu opisać jako wiele dyskretnych element&oacute;w na kt&oacute;re oddzia&#322;ywaj&#261; rozmaite procesy fizyczne. Komputery wykorzystywane s&#261; do oblicze&#324; zmian w czasie temperatury, ci&#347;nienia, wilgotno&#347;ci, pr&#281;dko&#347;ci przep&#322;ywu, i innych wielko&#347;ci opisuj&#261;cych element powietrza. Zmiany tych w&#322;asno&#347;ci fizycznych powodowane s&#261; przez rozmaitego rodzaju procesy, takie jak wymiana ciep&#322;a i masy, opad deszczu, ruch nad g&oacute;rami, tarcie powietrza, konwekcj&#281;, wpływ promieniowania s&#322;onecznego, oraz wp&#322;yw oddziaływania z innymi cz&#261;stkami powietrza. Komputerowe obliczenia dla wszystkich element&oacute;w atmosfery daj&#261; stan atmosfery w przysz&#322;o&#347;ci czyli prognoz&#281; pogody.<br>
W dyskretyzacji r&oacute;wna&#324; ruchu powietrza wykorzystuje si&#281; metody numeryczne r&oacute;wna&#324; r&oacute;&#380;niczkowych cz&#261;stkowych - st&#261;d nazwa numeryczna prognoza pogody.<br>
<br>Zobacz Wikipedia, Numeryczna prognoza pogody, <a href="http://pl.wikipedia.org/wiki/Numeryczna_prognoza_pogody" target="_blank">http://pl.wikipedia.org/wiki/Numeryczna_prognoza_pogody</a> (dost&#281;p lut. 9, 2010, 20:49 UTC).<br>
</div></div>
</div>