Extended-range reforecasts (43R1)

15-member coupled IFS (cycle 43R1) extended-range reforecast experiment covering the period 1989-2015. The atmosphere is configured with 91 vertical levels and uses the Tco399 cubic octahedral reduced Gaussian grid. The IFS is coupled hourly to the 75 level version of the NEMO v3.4 ocean model and the LIM2 sea-ice model, both of which use the ORCA025 tripolar grid. Coupling follows the implementation used in ECMWF operational forecasts. During the first 10 days of the forecast, SSTs seen by the atmosphere are derived by adding ocean model SST tendencies to observed values at initialization time that correctly represent the position of high-resolution features such as ocean fronts. From day 10 onwards, the ocean and atmosphere are freely coupled and ocean SST biases develop without constraint. Atmospheric fields are initialized from the ERA-interim reanalysis and ocean/sea-ice fields are initialized using the ORAS5 ocean (re)analysis.

Research experiments
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