NetCDF Format Versions

12.0 NetCDF Format Versions

There are several ways to represent netCDF data.

The first version of the netCDF file format, designed in 1988, is still supported. Other netCDF format variants have been created as needed.

NetCDF representations:

classic — the only format for netCDF data created between 1989 and 2004 by various versions of the reference software from Unidata. Supports the classic data model.
64-bit offset — introduced in late 2004 with version 3.6 for creation of and access to much larger files. Supports only the classic data model. Works fine on 32-bit platforms. Very similar to the classic format except for use of 64-bit file offsets for start of variables. Still has size restrictions, for example 4 GiB per record for variables.
netCDF-4 — implementation of enhanced netCDF API using enhanced HDF5 as a storage layer. Requires HDF5 1.8.5 or later. Supports both classic and enhanced data model. Adds performance features as well as support for enhanced netCDF model.
netCDF-4 classic model — variant of HDF5-based netCDF-4 format that supports only classic data model. Supports performance benefits while preserving API compatibility with netCDF-3 software.