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Sea-surface temperature (SST) and ice concentration

Sea-surface temperature is taken from various providers, who process the observational data in different ways.  Each provider uses data from several different observational sources.  Satellites measure sea-surface temperature (SST) in a layer a few microns thick in the uppermost mm of the ocean, drifting buoys measure SST at a depth of about 0.2-1.5m, ships sample sea water down to about 10m while the vessel is underway. Diurnal variations are not seen at deeper measurements. At ECMWF, sea-surface temperature are initialised using analyses received daily from the Met Office (OSTIA, 5 km resolution).  Sometimes sea-surface temperature is taken from a forecast made by coupling the NEMO ocean model to the ECMWF Integrated Forecasting System.  In this case, the SST is the average temperature of the uppermost metre of the ocean and does exhibit diurnal variations.

Sometimes sea-surface temperatures derived from satellites are shown over lakes or over model a land areas near the coast.  These are set to that of the Flake model mixed layer temperature.  This gives a much smoother field than Cy48r and earlier, helping to give much more realistic values around coastlines. 

Additionally  Additionally NEMO, and the LIM2 subprogram within it, forecast changes in the sea-surface temperature (SST) and sea ice evolution.  The Louvain-la-Neuve Sea Ice Model (LIM2) is a prognostic sea-ice model that deals with the dynamic and thermodynamic evolution of the sea surface so that sea-ice cover evolves dynamically.  It is incorporated into the dynamic ocean model (NEMO).    Output from these programs are used interactively by all IFS atmospheric models.  HRES  Ensemble Control Forecast (ex-HRES) uses the same initial ice extent as ENS medium range ensemble.  

Note: ECMWF uses LIM2 which is an earlier version of the Louvain-la-Neuve sea ice model currently available (Version 3.6).

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