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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.
The basis of the model is a single simple formula which assumes constant wind speed and reflection from the ground surface. The horizontal and vertical dispersion parameters are a function of downwind distance and stability. The model was developed for routine applications in air quality assessment, regulatory purposes and policy support.
The global models are run at varying times into the future. The UKMET Unified model is run six days into the future, [28] the European Centre for Medium-Range Weather Forecasts model is run out to 10 days into the future, [29] while the Global Forecast System model run by the Environmental Modeling Center is run 16 days into the future. [30]
Climate models divide the planet into a 3-dimensional grid and apply differential equations to each grid. The equations are based on the basic laws of physics, fluid motion, and chemistry. Numerical climate models (or climate system models) are mathematical models that can simulate the interactions of important drivers of climate.
The global models are run at varying times into the future. The Met Office's Unified Model is run six days into the future, [55] the European Centre for Medium-Range Weather Forecasts model is run out to 10 days into the future, [56] while the Global Forecast System model run by the Environmental Modeling Center is run 16 days into the future. [57]
Even with the increasing power of supercomputers, the forecast skill of numerical weather models only extends to about two weeks into the future, since the density and quality of observations—together with the chaotic nature of the partial differential equations used to calculate the forecast—introduce errors which double every five days ...
The Climate Forecast System or coupled forecast system (CFS) is a medium to long range numerical weather prediction and a climate model run by the National Centers for Environmental Prediction (NCEP) to bridge weather and climate timescales. [1] Version 2 became operational as CFSv2 in 2011. [2]
Numerical weather prediction models are equations describing the evolution of the atmosphere, typically coded into a computer program. When these models are used for forecasting the model output quickly deviates from the real atmosphere. Hence, we use observations of the atmosphere to keep the model on track.