Standards and Conventions
File formatting
- The output files are written through the NetCDF API
- The NETCDF4 _CLASSIC model will be adopted
- Recommended deflation level deflate=6
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)
- There is flexibility in specifying how many time slices (samples) are stored in a single file. A single file can contain all the time-samples for a given variable and climate experiment, or the samples can be distributed in a sequence of files.
- Recommended maximum file size of 4GB
File Naming
<institute>_<stream>_<modeling realm>_<frequency>_<level>_<production date and start date identifier>_<data year><data month><data day>[-<data year><data month><data day>]_<variable MARS name>_<ensemble member>
examples:
egrr_enfh_atmos_day_sfc_201601A_19950417-19950418_ta_r3.nc
egrr_enfh_atmos_month_plev_201601A_199504-199505_ta_r3.nc
"201601A" is a placeholder while a form for representing the model version, production year and startdate is determined:
egrr_enfh_atmos_month_plev_P2016_M1A_S19950401_199504-199505_ta_r3.nc
P=production year
M=model version
S=startdate
e.g. could the filename (alternatively) be something like:
egrr_enfh_atmos_month_plev_S19950401_199504-199505_ta_r3p20160101m411.nc
Metadata
- Much of the metadata written to the output files is defined in MIP-specific tables of information, which in this document are referred to simply as "MIP tables" in ASCII files.
- 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