NetCDF I/O Library and Related Softwares at NERSC

• NetCDF
• NetCDF Operators (NCO)
• NCVIEW
• NCCMP
• Climate Data Operators (CDO)

The NetCDF (network Common Data Form) library provides a set of programming interfaces that can be used for storing and retrieving scientific data. It also defines a machine-independent format for representing scientific data. The netCDF software was developed at the Unidata Program Center in Boulder, Colorado.

Files written with previous versions can be read or written with the current version.

How to use NetCDF Library

• On Cray XT4 (Franklin)

       % module load netcdf 
       % ftn  ... $NETCDF 
       % cc  ... $NETCDF 
       % CC  ... $NETCDF 
  

  Notice that on Franklin, all objective files need to present before the netcdf libraries while linking.
• On Bassi
  • 32-bit library

    % module load netcdf_32 
    

         % xlf  $NETCDF ... 
         % xlc  $NETCDF ... 
         % xlC  $NETCDF ... 
    

  • 64-bit library

    % module load netcdf 
    

         % xlf -q64  $NETCDF ... 
         % xlc -q64  $NETCDF ... 
         % xlC -q64  $NETCDF ... 
    

• On opteron Linux cluster (Jacquard)

       % module load netcdf 
       % pathf90  $NETCDF ... 
       % pathcc  $NETCDF ... 
       % pathCC  $NETCDF ... 
  

• On SGI Altix (Davinci)

       % module load netcdf 
       % g77  $NETCDF ... 
       % gcc  $NETCDF ... 
       % g++  $NETCDF ... 
  

Example

• First, one must issue the module load command to set up paths and environment: module load netcdf.
• Example 1 s_ex1.f.
• The makefile that illustrates the use of environment variables set up by the module load command.
• To run this example do : make run_prog
• The file created in example 1 (using 4 processors) in CDL notation created by the command ncdump.

netCDF Operators (NCO)

The netCDF Operators (NCO) are a suite of file operators which facilitate manipulation and analysis of self-describing data stored in the netCDF or HDF4 formats.

To access netCDF operators, first load the module nco with module load nco. The nco module automatically loads the module netcdf.

NCVIEW

NCVIEW is a visual browser for NetCDF format files.

To use NCVIEW, first set up the necessary x-term environment, then load the module ncview with module load ncview. The ncview module automatically loads the module netcdf.

NCCMP

The NCCMP compares two NetCDF files bitwise or with a user defined tolerance (absolute or relative percentage).

To use NCCMP, first load the module nccmp with module load nccmp. The nccmp module automatically loads the module netcdf.

Climate Data Operators (CDO)

The Climate Data Operators (CDO) are a collection of command line Operators to manipulate and analyse Climate model Data. Supported data formats are GRIB, netCDF, SERVICE, EXTRA and IEG. There are more than 350 operators available.

To use CDO, first load the module cdo with module load cdo. The cdo module automatically loads the module netcdf.

Further information

• UNIDATA netCDF FAQ
• NetCDF User's Guide for C
• NetCDF User's Guide for Fortran