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Scenarios and time periods

Model simulations are available for recent-past (historical scenario) and future periods (RCP2.6, RCP4.5 and RCP8.5 scenarios for CMIP5 and CORDEX, and SSP1-2.6, SSP 2-4.5, SSP 3-7.0 and SSP 5-8.5 for CMIP6) with monthly temporal frequency. The historical scenario provides includes data for a pre-industrial period (1850-1900 for CMIP5 and CMIP6) and a modern period (1970-2005 / 1950-2005 / 1950-2014 for CORDEX / CMIP5 / CMIP6, according to data availability). Users should be aware that no data are available for the period 1901 – 1949 or in some cases 1901 - 1969 even though the CDS widget and the corresponding file name would suggest a continuous period. The future scenarios provide data for 2006-2100 / 2015-2100 for CORDEX and CMIP5 / CMIP6, respectively.

File format and archiving

Files have been generated using netcdf-c verion 4.4.1.1 and hdf5 version 1.8.18 libraries using NETCDF4 data model. The resulting files are NetCFD format and metadata is CF1.9¹² compliant allowing for string type NetCDF variables (used to define some attributes in the files, such as members). The attribute convention for data discovery is ACDD-1.3¹³ compliant (including reference, geospatial, etc.).
Data is stored in different files for different experiments, scenarios and variables/indices (using the naming convention experiment scenario_index.nc{_}), including all members (see Table A1.1) in the same file using the member attribute and the full time periods described in Section 2.3; this was done to facilitate long-term data archival in the IPCC-DDC and the resulting dataset contains 806 files with a total volume of 400 GB (high compression rate is used), with file sizes ranging from 5GB to 600 KB. The archiving convention can be adapted to facilitate CDS archiving, adopting other convention and/or splitting the files for different members and/or years.Data transfer can be done though either push or pull approaches at the CDS convenience. This will be agreed in the next coordination meeting with CDS representatives, scheduled for 12 September, during the C3S General Assembly.

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