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Initial condition uncertainty is represented by perturbing the starting conditions between the different ensemble members. This explores the range of starting conditions consistent with our knowledge of the current state of the atmosphere, together with its past evolution.
Weather forecasts generated by computer simulations of the atmosphere and ocean typically consist of an ensemble of individual forecasts. Ensembles are used as a way to attempt to capture and quantify the uncertainties in the weather forecasting process, such as uncertainty in the initial conditions and uncertainty in the parameterisations in the model.
The inspiration for adopting the word entropy in information theory came from the close resemblance between Shannon's formula and very similar known formulae from statistical mechanics. In statistical thermodynamics the most general formula for the thermodynamic entropy S of a thermodynamic system is the Gibbs entropy
Weather reconnaissance aircraft, such as this WP-3D Orion, provide data that is then used in numerical weather forecasts.. The atmosphere is a fluid.As such, the idea of numerical weather prediction is to sample the state of the fluid at a given time and use the equations of fluid dynamics and thermodynamics to estimate the state of the fluid at some time in the future.
Initial condition ensembles involve the same model in terms of the same atmospheric physics parameters and forcings, but run from variety of different starting states. Because the climate system is chaotic, tiny changes in things such as temperatures, winds, and humidity in one place can lead to very different paths for the system as a whole.
While the U.S. made an effort to document civilian casualty data during its presence in the country, the administration “had consistent problems in collecting and defining data, changed methods and failed to estimate the margin of uncertainty,” according to a report by the Center for Strategic and International Studies, a D.C.-based think tank.
The uncertainty principle, also known as Heisenberg's indeterminacy principle, is a fundamental concept in quantum mechanics. It states that there is a limit to the precision with which certain pairs of physical properties, such as position and momentum, can be simultaneously known. In other words, the more accurately one property is measured ...
The initial state of the atmosphere and/or the numerical weather prediction model configuration are slightly varied to provide a range of possible forecast solutions. [4] [5] The global ensemble prediction systems at MSC and NWS use slightly different, but equally valid methods to initialize and integrate the atmospheric state. By combining the ...