CDL Discussion

The Irregular Grids data model will be expressed in many forms, such as a UML or ontology. A popular expression is a description of the metadata and variable structures which make up a NetCDF file. These are CDL's, as described in ​http://geon.unavco.org/unavco/IDV_for_GEON_netcdf.html :

The netCDF package includes an ascii format, called CDL, to make ascii files that are equivalent to netCDF files. CDL files are complete inverses of the equivalent netCDF, and vice versa. CDL is convenient since you can create, read and edit an ascii file, and then convert it to a binary netCDF file. For the netCDF documentation about CDL, see ​Section 2.1.2 Network Common Data Form Language (CDL), ​CDL Syntax, and ​CDL data types. Other parts of the complete NetCDF documentation may be useful to you. CDL files end with extension ".cdl". NetCDF files (binary) end with extension ".nc".

We need to devise a similar set of metadata conventions and variable structures for unstructured grids

Topics to address

• Terminology
• GlobalAttributes
• MeshMetaData
• CellTypes
  • ExtrudedMesh
• StorageVsApplication
• Dimensions
• Variables

Example CDL files

• Strawman UgCellArrays
• FvCom
• ELCIRC/SELFE Bill Howe (​sample SELFE datasets)
• Mixed-grid ELCIRC: ​http://sura-vims-pe6600-1.vims.edu/~drf/SCOOP/ELCIRCmixed.cdl This uses a version of the OceanModelFiles? convention.
• ELCIRC triangular ​http://sura-vims-pe6600-1.vims.edu/~drf/NETCDF/ modified to use unstructured conventions with NCML
• addmore here!

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