Project: IPCC Data Distribution Centre : Fourth Assessment Report data sets - The Intergovernmental Panel on Climate Change (IPCC) has been established by WMO and UNEP to assess scientific, technical and socio-economic information, relevant for the understanding of climate change, its potential impacts and option for adaption and migration. Projection of future trends for a number of key variables are provided through this section of the DDC (http://ipcc-data.org/sim/gcm_clim/SRES_AR4 ). The SRES scenarios have been constructed to explore future developments in the global enviromental with special reference to the production of greenhouse gases and aerosol precursor emission. A set of four scenario families (A1, A2, B1, B2) have been developed that each of this storylines describes one possible demographic, polito-economic, societal and technological future. Model experiments, also using different forcing scenarios, were calculated at other modeling centres. The data represent a subset of data sets from the IPCC Model Output Archive at PCMDI (https://pcmdi.llnl.gov/mips/cmip3/). _ These datasets are available in netCDF and GRIB format. The dataset names are composed of - centre/model acronym (e.g. MPEH5: Max-Planck-Institute/Echam5) - scenario acronym (e.g. SRB1: SRES B1) - run number (e.g. 1: run 1) - format identifier (e.g. N: netCDF, G: GRIB) - variable acronym [with level value] (e.g. hur850: relative humidity, 850 hPa) --> example: MPEH5_SRB1_1_G_hur850 Summary: These data represent monthly averaged values of selected variables for the Data Distribution Centre (DDC) of the Intergovernmental Panel on Climate Change (IPCC). (see also http://www.ipcc-data.org/) The model output prepared for IPCC Fourth Assessment SRES A1B experiment. For this experiment there are 7 ensemble runs available. This simulation was initiated from year 2000 of, CCSM3 model run b30.030a and executed on, hardware cheetah.ccs.ornl.gov. The input external forcings are, "ozone forcing : A1B.ozone.128x64_L18_1991-2100_c040528.nc, "aerosol optics : AerosolOptics_c040105.nc, "aerosol MMR : AerosolMass_V_128x256_clim_c031022.nc, "carbon scaling : carbonscaling_A1B_1990-2100_c040609.nc, "solar forcing : Fixed at 1366.5 W m-2, "GHGs : ghg_ipcc_A1B_1870-2100_c040521.nc, "GHG loss rates : noaamisc.r8.nc, "volcanic forcing : none, "DMS emissions : DMS_emissions_128x256_clim_c040122.nc, "oxidants : oxid_128x256_L26_clim_c040112.nc, "SOx emissions : SOx_emissions_A1B_128x256_L2_1990-2100_c040608.nc, " Physical constants used for derived data:, " Lv (latent heat of evaporation): 2.501e6 J kg-1, " Lf (latent heat of fusion ): 3.337e5 J kg-1, " r[h2o] (density of water ): 1000 kg m-3, " g2kg (grams to kilograms ): 1000 g kg-1, Integrations were performed by NCAR and CRIEPI with support, and facilities provided by NSF, DOE, MEXT and ESC/JAMSTEC. For model output data in higher temporal resulution and more variables visit the web page https://esg.llnl.gov:8443/home/publicHomePage.do.