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ENSEMBLES RT4 Coordinated Experiments


Experimental Design

Boundary conditions

Requested Diagnostics

Data Format




  Experimental Design for the Core AGCM Experiments

Boundary conditions:

  • Supplied by UREADMM (CGAM)
  • No interannual variability in boundary conditions to aid analysis of extreme events (better statistics)
  • For control experiments:
    • Climatological monthly mean SST & sea-ice concentrations derived from HadISST observations for 1961-1990
    • CO2 at average concentration for 1961-1990
  • For perturbed experiments (2xCO2):
    • Monthly mean SST & sea-ice concentration anomalies will be added to climatological fields used for control experiments
    • SST and sea ice anomalies will be derived from 1% pa CO2 CMIP-type integration with HadCM3 model. We will use the difference between two 30 year means: a) mean for period with CO2 values near present day b) mean for period with values near 2 x present day CO2.
    • CO2 at 2 x present day
  • Individual groups responsible for interpolating SST and sea-ice concentrations onto their model grid.

Duration of experiments:

  • For each of control and perturbed experiments, 2 x 25 year integrations with different initial conditions. 2 integrations to sample any drifts e.g. associated with memory in land surface. Ignore first 5 year of each integration giving 40 years of data to analyse for each experiment.
  • Use of a 360 day calendar if possible.

Diagnostics and data:

  • Requested ENSEMBLES RT4 Diagnostics list.
  • Common data archive at CGAM. Rules:
    • All data must be in CF compliant netCDF format . It is the responsibility of each group to provide the data in the correct format.
    • Data should be placed in a suitable location (e.g. www or anon ftp site) from where it can be retrieved by CGAM.
    • CGAM will manage a password protected www site giving access to the archive.


  • land/sea warming contrast just one aspect of interest
  • Please volunteer for diagnostic subprojects (email:




Maintained by Maria Noguer Walker Institute , Department of Meteorology , University of Reading , Early gate, PO Box 243, Reading RG6 6BB