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AIFS Single The Deterministic Model

Observations are assimilated using 4D-var to IFS grid point values over the whole globe with resolution about 9km.  Currently the AI procedures use grid points at a lower resolution about 0.25 of a degree (~25km).  The IFS analysed data is "encoded" to values at the AI grid point.  These data are then fed to the AI procedure which uses the algorithms derived by the ML trained by minimising RMS error.   The algorithm is not complicated and consequently has fast execution allowing a complete global forecast to be made much faster than IFS and other physics-based models.  Forecasts are made in six hour time steps and output from one time step is used as the input for the next step.  Currently the AI forecasts use 12 repeated six hour time steps to extend the forecast to T+72.   Intermediate forecast data is only available at the simulated six hour time steps; no information is available at smaller intervals than six hours.

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