NetCDF (network Common Data Form) is a set of interfaces for array-oriented data access and a freely-distributed collection of data access libraries for C, Fortran, C++, Java, and other languages. The netCDF libraries support a machine-independent format for representing scientific data. Together, the interfaces, libraries, and format support the creation, access, and sharing of scientific data. NetCDF data is: Self-Describing. A netCDF file includes information about the data it contains. Portable. A netCDF file can be accessed by computers with different ways of storing integers, characters, and floating-point numbers. Scalable. A small subset of a large dataset may be accessed efficiently. Appendable. Data may be appended to a properly structured netCDF file without copying the dataset or redefining its structure. Sharable. One writer and multiple readers may simultaneously access the same netCDF file. Archivable. Access to all earlier forms of netCDF data will be supported by current and future versions of the software. The netCDF software was developed by Glenn Davis, Russ Rew, Ed Hartnett, John Caron, Steve Emmerson, and Harvey Davies at the Unidata Program Center in Boulder, Colorado, with contributions from many other netCDF users.