Model Configurations
The IFS models the dynamics of the atmosphere and the physical processes that occur, and also other processes that influence the weather e.g. atmospheric composition, surface energy fluxes, the marine environment and processes at the atmosphere/surface interface (then scroll down to soil/surface section). Several configurations of the atmospheric model are used, each tailored towards a specific aim (HRES and ENS control for detail in the forecast during the first 10 days, Ensemble (ENS) to investigate uncertainty in the forecast during the first 15days, and extended ENS and Seasonal runs to give probability of general conditions at longer ranges). There are some slight differences, but generally the same model structure is used in each of the different model configurations. The relative skill of the models and their strengths have been investigated.
With IFS Cycle 48r1, the horizontal resolution of the medium-range ensemble(ENS) will increase from 18 to 9 km. This will bring the ENS to the same horizontal resolution as the high resolution forecast (HRES). The vertical resolution for both ENS and HRES will remain at 137 model levels and the ENS will continue to have 50 perturbed forecasts.
Cycle 48r1 will also bring a major upgrade to the configuration of the extended-range ensemble (ENS extended): Rather than being an extension of the medium-range forecasts starting twice a week at day 15 it will be a completely separate system, running daily from 00 UTC out to day 46 with 100 members. The resolution will remain unchanged at 36 km horizontally and 137 model levels.
As a result of these configuration changes Cycle 48r1 will offer two sets of re-forecasts, one for the medium range and one for the extended range.
Overview
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