Unidata

NetCDF 4.0.1 Release Notes

We are pleased to announce the release of a new version of netCDF: version 4.0.1.

The source distribution for netCDF 4.0.1 is now available in compressed tar or gzipped tar form. Instructions for installation are available in the INSTALL file that accompanies the software or online.

Version 4.0.1 provides full compatibility with existing netCDF programs and data. This release adds performance enhancements, an upgraded Fortran 90 API, ncdump handling of netCDF-4 features, bug-fixes, and portability improvements.

This release also includes an experimental release of ncgen4 and the opendap client. These features are being prepared for full release in netCDF-4.1, but are optionally available for intrepid users who want to gain early access to these new features.

For more information about netCDF-4, see

• an overview in NetCDF-4: Software Implementing an Enhanced Data Model for the Geosciences
• recent guidance in Experience with an Enhanced NetCDF Data Model and Interface for Scientific Data Access
• The NetCDF Tutorial.

To use the extended netCDF-4 data model and features, this release requires that the --enable-netcdf-4 argument be provided to configure. Without this, the netCDF classic library will be built, without the capability to read or write netCDF-4/HDF5 files. If --enable-netcdf-4 is used, the HDF5 1.8.2 release, and the zlib 1.2.3 (or later) release are required.

Build and install zlib and HDF5 (if needed), and netCDF, as described in the netCDF-4 installation instructions.

This release has been tested on a wide variety of platforms; see the netcdf-4.0.1 test page. (Unidata site registration required).

Changes Since netcdf-4.0 Release

• Added optional arguments to F90 API to nf90_open/create, nf90_create_var, and nf90_inquire_variable so that all netCDF-4 settings may be accomplished with optional arguments, instead of separate function calls.
• Added control of HDF5 chunk cache to allow for user performance tuning.
• Changed default chunking to better handle very large variables; made contiguous the default for fixed size data sets with no filters.
• Added "-s" option to ncdump to display performance characteristics of netCDF-4 files as special virtual attributes, such as _Chunking, _DeflateLevel, _Format, and _Endianness.
• Added "-t" option to ncdump to display times in human readable form as strings. Added code to interpret "calendar" attribute according to CF conventions, if present, in displaying human-readable times.
• Performance refactoring of core netCDF-4/HDF5 read/write code.
• Additional parallel I/O tests and benchmarks.
• Added experimental OPeNDAP support based on a new C-only implementation. This is enabled using --enable-dap option and requires libcurl. The configure script will attempt to locate libcurl, but if it fails, then its location must be specified by the --with-curl option.
• Improved portability, especially on high performance platforms.
• Included latest netCDF classic core library code.

CAUTION:

The netCDF ncgen utility does not yet handle enhanced model netCDF-4 features, like groups and compound types. (Ncgen does handle netCDF-4/HDF5 files which don't make use of the new expansion of the data model). Ncgen will be able to handle such advanced features in the netCDF-4.1 release. An experimental ncgen, called ncgen4, is available in this release. Use the --enable-ncgen4 option to configure to build the ncgen4 tool.

Providing Feedback

Questions or suggestions about this release may be sent to <support-netcdf@unidata.ucar.edu>, mentioning the platform and version of the software.