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This is still a work in progress... Text in black can be considered well-established, but text in orange is still under discussion |
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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
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- 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
A file containing a hash created with sha256sum should be created for each file
Code Block language bash title Create hash files sha256sum filename.nc > filename.sha256
File Naming
NEW PROPOSAL (20170419):
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<institute_id>_<model_id tag>_
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<forecast_type>_<start date identifier>_
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OLD PROPOSAL:
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<modeling realm>_<frequency>_
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<level_type>_<variable name>_<ensemble member>
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examples:
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.nc
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<model_
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id_tag> as it is defined in the description of the "source" global attribute
<institute_id>, <forecast_type>, <modeling_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
"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: e
grr_enfh_atmos_month_plev_S19950401_199504-199505_ta_r3p20160101m411.nc
NOTE: The file name should be able to be rebuilt from the contents of the file
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
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