Modeled Global Climate Data from the CCCma First Generation Coupled General Circulation Model (CGCM1)

The Canadian Center for Climate Modelling and Analysis (CCCma) First Generation Coupled General Circulation Model (CGCMI) was used to run simulations of 20th century climate and projections of climate into the 21st century. The atmospheric component of the model is essentially the CCCma Second Generation Atmospheric General Circulation Model (GCMII). It is a spectral model with triangular truncation at wave number 32 (yielding a surface grid resolution of roughly 3.7 degree latitude-longitude) and 10 vertical levels. The ocean component is based on the Geophysical Fluid Dynamics Laboratory (GFDL) Modular Ocean Model (MOM) 1.1 code and has a resolution of approximately 1.8 degree latitude-longitude and 29 vertical levels. The model uses heat and water flux adjustments obtained from uncoupled ocean and atmosphere model runs (of 20 years and 4000 years duration respectively), followed by an `adaption' procedure in which the flux adjustment fields are modified by a 14 year integration of the coupled model. The climate sensitivity of CGCM1 is about 3.5 deg-C. References to publications with more specifics on the model structure and simulations can be found at the IPCC DDC web site mentioned below.

Four climate change simulations have been performed with the CCCma CGCMI. Three of these simulations use an effective greenhouse gas forcing change corresponding to that observed from 1850 to the present, and a forcing change corresponding to an increase of CO2 at a rate of 1% per year (compounded) thereafter until year 2100. The direct forcing effect of sulphate aerosols is also included by increasing the surface albedo based on loadings from a sulphur cycle model. The fourth simulation considers the effect of greenhouse gas forcing only. There was also a 200-year control simulation with constant CO2.

Mean monthly time-step data from the CCCma CGCMI simulations are archived and distributed by the Intergovernmental Panel on Climate Change (IPCC) Data Distribution Center (DDC) at [http://ipcc-ddc.cru.uea.ac.uk/index.html]. Data are available for each of the three ensemble members in the greenhouse gas plus sulphate simulation as well as a mean for the entire ensemble. Data are also available for the greenhouse gas simulation. Mean monthly values are available for the 1961-1990 time slice. Mean monthly change fields with respect to 1961-1900 are available for each of the following time slices: 2010-2039, 2040-2069, 2070-2099. The variables represented in these data are: diurnal surface air temperature range (C), total precipitation rate (mm/day), total incident solar radiation at the surface (W-m**2), minimum and maximum surface air temperature (C), surface vapor pressure (hPa), and 10m wind speed (m/s). The IPCC DDC also provides the land-sea mask and topography data sets used with the model simulations. The data are available for download as zipped ASCII files, once the user has registered through the IPCC DDC web site. Registration is free and indicates that the user has read and agreed to abide by the IPCC DDC data policy at [http://ipcc-ddc.cru.uea.ac.uk/ddc_policy.html]. Documentation and discussion relating to these simulations, the model, and data are available on the IPCC DDC web site. These data are also available on CD-ROM along with similar results from other global climate models.

The full set of monthly results from the CCCma CGCMI simulations can be obtained from the DDC Global Climate Model (GCM) Archive hosted at the German Climate Computing Centre (DKRZ), Hamburg. Monthly time series for the years 1900-2099 for the control run, the greenhouse integration, and the greenhouse gas plus sulphate integrations are available for the following variables: total surface radiation (W/m**2), mean sea level pressure (Pa), total precipitation rate (mm/day), air surface temperature (K), maximum and minimum surface air temperature (K), surface specific humidity (kg/kg), and 10m wind speed (m/s). The web site allows users to download data files from the DDC in two formats, GRIB (machine independent, self-descriptive binary format, WMO standard) and GZIP (compressed ASCII format). Documentation on data format and information on extracting and reading the data are also available. Additional variables and resolutions are available from the Canadian Center for Climate Modelling and Analysis at [http://www.cccma.bc.ec.gc.ca/data/cgcm1/cgcm1.shtml].