NCEPLIBS

Introduction

NCEPLIBS is a collection of libraries used by a range of NCEP R&D and operational applications, including UFS (Weather Model, SRW, etc.), GSI/Global Workflow, UFS_UTILS, and UPP. General information about NCEPLIBS, including code best practices, contributor expectations, and continuous integration methods, can be found in the NCEPLIBS wiki.

For using NCEPLIBS on NOAA HPC systems, see the spack-stack project’s Getting Started documentation and wiki. The spack-stack framework is used to install a range of libraries, including all currently supported NCEPLIBS codes, on RDHPCS systems in locations available to all users. The documentation also provides instructions for using spack-stack to build software stacks from scratch, as well as to build stacks that are chained to existing environments in order to re-use dependencies already provided by official spack-stack deployments.

[!WARNING]
This repository contains long disused scripts for compiling NCEPLIBS. These are not in any way maintained or supported. Use as at your own risk. See instructions below for obtaining NCEPLIBS.

NCEPLIBS is comprised of the following libraries. Italicization indicates a repository that as of Summer 2025 is no longer actively developed, therefore NOAA developers are suggested to avoid using them, or to confer with the NCEPLIBS team before beginning any development work with them.

NCEP library	Spack package name	Description
NCEPLIBS-bacio	bacio	Binary I/O for the NCEP models
NCEPLIBS-bufr	bufr	Working with the BUFR format
NCEPLIBS-g2	g2	Coding/decoding GRIB2 messages
NCEPLIBS-g2c	g2c	C decoder/encoder routines for GRIB edition 2
NCEPLIBS-g2tmpl	g2tmpl	Utilities for GRIB2 templates
NCEPLIBS-gfsio	gfsio	Convert GFS Gaussian output into grib output
NCEPLIBS-grib_util	grib-util	Utilities for working with GRIB2 files
NCEPLIBS-ip	ip	General interpolation library
NCEPLIBS-landsfcutil	landsfcutil	Initializing land-surface states
NCEPLIBS-ncio	ncio	Read the GFS forecast files
NCEPLIBS-nemsio	nemsio	I/O for the NCEP models using NEMS
NCEPLIBS-nemsiogfs	nemsiogfs	I/O for the NEMS-GFS model
NCEPLIBS-prod_util	prod-util	EMC copy of NCO’s utilities for misc. date & file manipulation
NCEPLIBS-sfcio	sfcio	Surface files I/O
NCEPLIBS-sigio	sigio	I/O on the sigma restart file of the global spectral model
NCEPLIBS-w3emc	w3emc	Decoder/encoder routines for GRIB edition 1
NCEPLIBS-wrf_io	wrf-io	Lightweight WRF-IO API library for Unified Post Processor (UPP)
wgrib2	wgrib2	Utility for working with GRIB2 files

For information on maintainers, documentation, and bug and feature requests, refer to each package repository listed above.

The NCEPLIBS-w3nco, NCEPLIBS-ip2, and NCEPLIBS-sp libraries (‘w3nco’, ‘ip2’, and ‘sp’ in Spack, respectively) are deprecated. NCEPLIBS-w3emc replaces NCEPLIBS-w3nco, and NCEPLIBS-ip replaces NCEPLIBS-ip2 and NCEPLIBS-sp.

Supported compilers and required software

NCEPLIBS codes are tested with and intended to support GCC, Intel Classic, and Intel oneAPI compilers. Older versions of each of these may not be compatible. Refer to individual code repositories (including GitHub Issues) for more specific information on compiler conflicts, and please submit issues if previously unknown conflicts emerge. Contributions of modified code and CMake configurations to allow for the use of other compilers are welcome, but compilers other than those listed above are not officially supported.

All NCEPLIBS codes use the CMake build system, therefore CMake and at least one of GMake and Ninja are necessary to build them.

Obtaining, building, and using NCEPLIBS

[!NOTE]
Users are recommended to use existing spack-stack installations as much as possible when using NOAA R&D systems, and to use spack-stack as much as possible when developing the applications that spack-stack is intended to support, namely, UFS applications, Global Workflow, and JEDI applications (for instance, users developing the UFS Weather Model on a personal machine are recommended to build a local copy of spack-stack). Outside of these platforms and applications, users are recommended to install NCEPLIBS either through CMake or through regular Spack (not spack-stack); see instructions below.

With Spack

All of the NCEPLIBS codes can be installed through the Spack package manager. One significant benefit of using Spack is that it will automatically install any dependencies needed, including CMake, and even compilers. See the Spack documentation for details of configuring and executing Spack installations. Spack also has extensive capabilities including source and build caching, parallel installation, dynamically generating Tcl and Lmod environment modules, and creating Docker and Singularity container images.

In the simplest case, with the spack command loaded into the current environment, run, for example, spack install ip to install the latest release of the NCEPLIBS-ip library; Spack will take care of installing all necessary dependencies. See the above table for each package’s name in Spack. The develop branch for each library can be installed by specifying the ‘develop’ version, i.e., spack install w3emc@develop.

Here is a typical set of steps for installing and using NCEPLIBS using Spack, assuming that Spack’s own prerequisites are already installed:

git clone https://github.com/spack/spack
. spack/share/spack/setup-env.sh # assuming bash, zsh, or dash shell
spack external find cmake gmake openblas # optionally find external packages to save time
spack install ip@develop precision=4,d,8
spack load ip

The spack load command configures the $CMAKE_PREFIX_PATH variable, in this example making the ip library available to downstream CMake projects (e.g., UFS Weather Model).

For any bugs or other issues with Spack-based installations, such as incorrect dependencies in a package’s recipe, please file an issue under the main Spack repository.

With CMake

For CMake build instructions, including software prerequisities and build options, refer to each NCEPLIBS repository’s README and ReadTheDocs page. The GitHub Actions workflows under .github/workflows/ in each NCEPLIBS repository may be useful references for possible approaches to obtaining software prerequisites.

Usage

NCEPLIBS can be used in any application that uses cmake to configure and build by adding -DCMAKE_PREFIX_PATH=<nceplibs-prefix> to the CMake command line during configuration. Note that if NCEPLIBS codes are installed through Spack, loading the packages, either through Spack-built environment modules or using the spack load command, will by default populate the $CMAKE_PREFIX_PATH environment variable with the appropriate paths.

Disclaimer

The United States Department of Commerce (DOC) GitHub project code is provided on an “as is” basis and the user assumes responsibility for its use. DOC has relinquished control of the information and no longer has responsibility to protect the integrity, confidentiality, or availability of the information. Any claims against the Department of Commerce stemming from the use of its GitHub project will be governed by all applicable Federal law. Any reference to specific commercial products, processes, or services by service mark, trademark, manufacturer, or otherwise, does not constitute or imply their endorsement, recommendation or favoring by the Department of Commerce. The Department of Commerce seal and logo, or the seal and logo of a DOC bureau, shall not be used in any manner to imply endorsement of any commercial product or activity by DOC or the United States Government.