NetCDF Status

Russ Rew, Ed Hartnett, and Dennis Heimbigner
April 3, 2008

This report updates the last status report of Unidata's netCDF development efforts since the User Committee meeting in October 2007.

NetCDF and Unidata

Work in maintaining, supporting, and developing the netCDF data model and software is associated with Endeavor 6: Improved scientific data access infrastructure from the Unidata 2008 proposal. NetCDF continues to serve as a key infrastructure element for data providers and users of climate, atmosphere, and ocean data.

Recent netCDF development aims at generalizing the netCDF data model, improving client access to remote data services, improving interoperability with other representations for scientific data, making the netCDF interface more suitable for use on high-end parallel platforms with high-resolution models, and providing netCDF software on a wide range of platforms.

NetCDF-4/HDF5 Development

NetCDF-4, the next major upgrade to netCDF, uses the HDF5 format to read and write data files through the netCDF API. This allows the introduction of many new features, including compression, parallel I/O, multiple unlimited dimensions, user-defined data types, and more. NetCDF-4.0 depends on new features available in HDF5 version 1.8.0, which was finally released in February, 2008.

A full netCDF-4 release that uses the new HDF5 1.8 version is scheduled for release in June 2008. In the meantime, a snapshot that works with the most recent HDF5 library is available for testing, as the final wrinkles are worked out. Recent development work has improved performance by using new benchmarking tests, improved the way parallel I/O works, refined the Fortran interfaces, improved the build system, and made the ncdump utility available as the first C application that can handle all the new features of the netCDF-4 data model. User documentation has also been extensively revised.


In January Dennis Heimbigner joined Unidata to work on a new NSF-funded cyberinfrastructure project for improving OPeNDAP and netCDF Integration by

The work is proceeding on schedule with the initial milestone already substantially accomplished: moving the existing OPeNDAP C++ client library into Unidata's code base, integrating it into Unidata's development framework, and testing the integrated system on multiple platforms.

GOES-R Products to be Provided in NetCDF-4

The NOAA GOES-R project, in a Ground Segment Specification requires making available all L2 and L2+ products in netCDF-4 format. As a result, we expect GOES-R participation in our next netCDF training workshop, and a need to support the GOES-R Algorithm Working Group to help develop netCDF-4 representations for products.

The NetCDF-Java Library

Version 2.2.22 of the netCDF-Java library was released in February 2008. Recent versions have added netCDF-4, HDF4, CADIS, and GEMPAK I/O Service Provider classes, useful new aggregation types expressible in NcML, ability to handle additional GRIB files such as thin grids and Gaussian grids, bzip2 compression, and bug fixes. Meanwhile, work continues on NetCDF-Java 4.0, with release expected in June 2008.

Presentations at AGU and AMS

At the annual AGU meeting in December, Russ presented a talk on The CF Conventions: Governance and Community Issues in Establishing Standards for Representing Climate, Forecast, and Observational Data.

Ed and Russ developed some benchmarks for netCDF-4 and Ed presented a talk at the annual AMS meeting in January on Experience with an Enhanced NetCDF Data Model and Interface for Scientific Data Access.

by Russ Rew