Extended-range reforecasts (43R1) with bias-corrected North Atlantic sea surface temperatures

15-member coupled IFS (cycle 43R1) extended-range reforecast experiment covering the period 1989-2015 with bias-corrected sea-surface temperatures (SSTs) in the North Atlantic region. This experiment can be compared with gkzp, which is the relevant control without bias-correction. 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. The ocean receives atmospheric fluxes as normal, but the SSTs seen by the atmosphere are adjusted using the model SST bias derived from gkzp, which varies as a function of location, calendar start date, and forecast lead time. This bias-correction term is applied only in the North Atlantic region (80°W-0°E, 25°N-90°N) and is smoothly reduced to zero at the edge of the domain. Coupling is otherwise as in operational configurations of IFS cycle 43R1. Atmospheric fields are initialized from the ERA-interim reanalysis and ocean/sea-ice fields are initialized using the ORAS5 ocean (re)analysis.

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