The GECCO2 ocean synthesis is the German contribution of the Estimating the Circulation and Climate of the Ocean project (ECCO, www.ecco-group.org). The synthesis uses the adjoint method to adjust the initial temperature and salinity in 1948 together with the air temperature, humidity, precipitation, and zonal and meridional wind every 10 days to bring the model into consistency with the data, which derive from the EN3v2 data base AVISO along track SLA , GOCO mean dynamic topography, HadISST, AMSRE SST, and the WOA09 climatology. The global model is based on the MITgcm model, has 50 levels, and uses zonally 1 degree and meridionally varying higher resolution. The background atmospheric state is taken from the 6 hourly NCEP/NCAR Reanalysis 1.
The GECCO2 synthesis covers the period 1948-2011. For the last iterations, the synthesis was partitioned into overlapping 5 year windows. Since only the initial condition in 1948 is allowed to change in GECCO2, the atmospheric state is the only control for all windows except for the first one. The synthesis was extended twice, into the year 2013 and 2014, respectively, by taking the initial conditions of iteration 28 from the end of 2008.
Resolution: 1x1/3°, 50 z-levels, partial cells
Data assimilated: EN3_v2a T/S (XBT corrected)+ AVISO along track SLA , GOCO MDT, HadISST, AMSRE SST, WOA09 climatology
Assimilation method: 4D-VAR (adjoint) method
Forcing and relaxation used: NCEP RA1 atm. Fields, Bulk formulae, Large and Yeager, 2009