ECMWF operational analysis system (S3)


Product description

ECMWF has implemented an operational ocean analysis system called S3 which provides initial conditions for both seasonal and monthly forecasts. The S3 analysis extends back to 1959, so it is a historical ocean re-analysis that is updated on a daily basis.

The two analysis products that S3 delivers are: a delayed product 11 days behind real time (BRT) used to initialize the seasonal forecasts and an early delivery product run in near real time (NRT) used by the monthly forecasts. The two products are very similar and differ mainly in the assimilation time period.

Many data types are assimilated into the S3 system including subsurface temperature, altimeter derived sea- level anomalies and salinity data. The different in situ temperatures assimilated include Argo, XBTs, moorings, and SuperObs, where Argo contributes the largest number of profiles.

Ocean parameters

The following parameter outputs of the S3 NRT system can be found here. For many of the outputs listed below, there are horizontal maps and equatorial longitude-time diagrams. There are zonal and meridional sections of temperature and temperature anomaly.

  • SST and SST anomaly
  • Zonal wind stress
  • Sea level
  • Depth of 20° isotherm
  • Surface salinity and anomaly
  • Temperature and salinity averaged in upper 300m
The parameters listed above are also outputs of the BRT system and can be found here. The difference is that the maps are weekly or monthly instead of daily. There is also an equatorial option and observation coverage maps are available.

Resolution

S3 resolution is 1° by 1° except around the equator where it gradually increases to 0.3° in the meridional direction. There are 29 vertical levels with a typical thickness of 10m in the upper ocean.


S3 BRT: Temperature anomaly at 140° W


S3 NRT: Averaged salinity in upper 300m

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