CF-NETCDF.NC

Basic Information

File-Type

cf-netcdf.nc

File-Form

UNFORMATTED

Version

May 2012

Description-Date

August 2014

Significance of the File

• BAW instance of a NetCDF file.
• NetCDF conventions, used to store BAW specific data, are documented in detail in the NetCDF-Pages of BAW-Wiki.
• CF compliance verified using the NCAS CF Compliance Checker.
• Since May 2011 NetCDF-4/HDF5 is supported (see Unidata, NetCDF).

File-Contents (in Catchwords)

1. header with metadata:
   1. list of dimensions (name and length),
   2. list of variables (name, type and dimension(s)) for which data are stored in the file,
   3. attributes related to variables (long_name, units etc.), and
   4. global attributes (title, history etc.).

   Remark: the names of attributes as well as standard variable names should be chosen according to the following given conventions:

   • NetCDF Climate and Forecast (CF) Metadata Convention.

2. data for all variables stored in the file:
   1. coordinate-variable data,
   2. data for ordinary variables, for which only one data record is stored in the file, and finally
   3. data for record-variables (which have one unlimited dimension, e.g. time), which can be stored several times.

READ performance for large CF-NetCDF data files may strongly depend on the inner structure of the data file. The size of a data block (or chunk) which is accessed by one READ is significant in this context. A file can be considered as well structured if time series access as well as spatial access can be executed with similar effort (number of READs required). This can be achieved using appropriate chunk sizes for the variables stored. More informations can be found here:

1. Chunking Data: Why it Matters, and
2. Chunking Data: Choosing Shapes].

Programs using this Type of File

ArcGIS, DATACONVERT, GRIDCONVERT, NCAGGREGATE, NCANALYSE, NCPLOT, QUICKPLOT, UNK, UNTRIM2, UNTRIM2007

Example-File

$PROGHOME/examples/lib/l_grid/lg.all_CF-NetCDF_Info.nc
$PROGHOME/examples/lib/h_grid/g05-Content.CF-NetCDF.nc
$PROGHOME/examples/lib/h_grid/UNTRIM-Content.CF-NetCDF.nc
$PROGHOME/examples/lib/h_grid/UTRSUB-Content.CF-NetCDF.nc
$PROGHOME/examples/lib/p_grid/profil05-Content.CF-NetCDF.nc $PROGHOME/examples/lib/io_insel/insel.netcdf-cf.nc

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