Changes between Version 10 and Version 11 of doc/app/netcdf

Timestamp:

Oct 5, 2010 11:00:44 AM (14 years ago)

Author:

heinze

Comment:

--

doc/app/netcdf

@@ -7 +7 @@
 In the following pages, steering of the different data output and how to create plots of the data is described by some examples. Not all details of steering are mentioned. If necessary, these can be found within the description of the respective parameters. For most purposes it should be sufficient to read [wiki:doc/app/ncgen Generation of a PALM netCDF file] and [wiki:doc/app/ncexample Example of a PALM netCDF data set] which explains the PALM-netCDF-output.
 
-The standard data output of PALM is netCDF (network Common Data Form) in 64-bit offset format. netCDF is an interface to a library of data access functions for storing and retrieving data in the form of arrays. netCDF is an abstraction that supports a view of data as a collection of self-describing, portable objects that can be accessed through a simple interface (protable means that netCDF data files can be read on any machine regardless of where they have been created). Array values may be accessed directly, without knowing details of how the data are stored. Auxiliary information about the data, such as what units are used, may be stored with the data. Generic utilities and application programs can access netCDF datasets (files) and transform, combine, analyze, or display specified fields of the data, e.g. the contents of a netCDF dataset can be viewed using the command '''ncdump''' (see further below). Many (public domain) graphic software has built in interfaces to read netCDF datasets (e.g. '''ferret''' or '''NCL''' ([wiki:doc/app/ncl see here])). The complete netCDF documentation is available from the netCDF homepage ([[http://www.unidata.ucar.edu/software/netcdf/]]). The netCDF tutorial for FORTRAN90 can also be found on our web server.
+The standard data output of PALM is netCDF (network Common Data Form) in 64-bit offset format. netCDF is an interface to a library of data access functions for storing and retrieving data in the form of arrays. netCDF is an abstraction that supports a view of data as a collection of self-describing, portable objects that can be accessed through a simple interface (protable means that netCDF data files can be read on any machine regardless of where they have been created). Array values may be accessed directly, without knowing details of how the data are stored. Auxiliary information about the data, such as what units are used, may be stored with the data. Generic utilities and application programs can access netCDF datasets (files) and transform, combine, analyze, or display specified fields of the data, e.g. the contents of a netCDF dataset can be viewed using the command '''ncdump''' (see further below). Many (public domain) graphic software has built in interfaces to read netCDF datasets (e.g. '''ferret''' or '''NCL''' ([wiki:doc/app/ncl see here])). The complete netCDF documentation is available from the netCDF homepage ([[http://www.unidata.ucar.edu/software/netcdf/|netCDF]]). The netCDF tutorial for FORTRAN90 can also be found at the netCDF homepage ([[http://www.unidata.ucar.edu/software/netcdf/docs/netcdf-f90/|netCDF for FORTRAN90]]).
 
 The general output format of PALM data is determined by the runtime-parameter [wiki:doc/app/d3par#data_output_format data_output_format] (data_output_format = 'netcdf', by default). For historical reasons, some alternative formats can be selected. The accuracy of the netCDF output data can be set with parameter [wiki:doc/app/d3par#netcdf_precision netcdf_precision]. By default, data have single (4 byte) precision. Runtime-parameter [wiki:doc/app/d3par#data_output_format data_output_format] can be used to choose between the different netCDF file formats (classic, 64-bit offset, netCDF4/HDF5). The 64-bit offset format allows creating large files (file size only limited by the underlying file system), but each output variable (array) is still limited to 2GB. In netCDF4 format, there is no limit for the size of variables, and it also allows parallel I/O into one output file. However, some (graphic) software still does not support netCDF4 format.