File formatting
- The output files are written through the NetCDF API
- The NETCDF4 _CLASSIC model will be adopted
- Recommended compression level deflate=6
- Shuffling=True
- Fletcher32=True is strongly recommended
File Structure
- Each netCDF4 file contains a single output variable (along with coordinate/grid variables, attributes and other metadata) from a single model and a single simulation (i.e., from a single ensemble member and a single start date)
- Recommended maximum file size of 4GB
A file containing a hash created with sha256sum should be created for each file
Create hash filessha256sum filename.nc > filename.sha256
File Naming
<institute>_<model_id tag>_<forecast_type>_<start date identifier>_<modelling realm>_<frequency>_<level_type>_<variable name>_<ensemble member>.nc
<model_id_tag> as it is defined in the description of the "source" global attribute
<institution_id>, <forecast_type>, <modelling_realm>, <frequency> and <level_type> coming from the global attributes of the same name
<start_date_identifier> being an string "SYYYYMMDDHH"
<variable_name> from the netCDF name of the variable (short name)
<ensemble_member> from the 'realization' coordinate value
Metadata
- The metadata is constrained by the CF convention (NetCDF Climate and Forecast (CF) Metadata Convention)
- This is also based on information from the SPECS_standard_output.pdf document, the CMIP5 tables and the Attribute Convention for Data Discovery.
- Attributes currently are a significantly reduced subset of the SPECS/CMIP5 requirements with minor adaptations