fremor

fremor CMORizes FRE output with CMOR. It is a conda package and it's documentation can be found on readthedocs.

python3.11:

python3.12:

python3.13:

python3.14:

Background and Purpose

fremor is a model output rewriter (CMORizer) for FRE/FMS based models and output. fremor (or fremor for short) is geared for standardizing NOAA-GFDL datasets for further quality control checks, assessments and data publishing pipelines in the context of CMIP7 using the CMOR library.

Relationship to fre-cli

fremor was originally the fre.cmor submodule of NOAA-GFDL/fre-cli and so stands on the shoulders of it's contributors, retaining it's general structure and lessons learned from it. Future re-integrations back into fre-cli, as a formal package dependency, are being assessed.

Contributors

AI Disclaimer

AI was heavily used in the creation of this repository, primarily github's copilot with Claude (opus4.6 sonnet4.6, and haiku), and Gemini and Chat-GPT models to a lesser extent, in agent mode. Claude and Codex agents have also contributed.

Installation / Access

Requirements

• python>=3.11
• click>=8.2
• cmor>=3.14.2
• netCDF4>=1.7
• numpy>=2
• pyyaml

For development and testing, pylint, pytest, and pytest-cov are all highly recommended as helpful additions.

via PPAN / modules (COMING SOON/TODO)

If you're trying to gain access to fremor functionality as quickly as possible:

# the current post-release in main
module load fremor/test

# a tagged version of fremor, post-releases will never be named modules
module load fremor/X.Y.Z

via conda

If you have a path to a fremor environment you can activate it like so:

conda activate some/path/to/fremor_env

If you want your own fremor environment:

# the environment will be named fremor_en
conda create -n fremor_env NOAA-GFDL::fremor

# see fremor_env in the list --> activate it by name
conda env list
conda activate fremor_env

or, if you've already activated a conda environment

conda create -n empty_env
conda activate empty_env
conda install -c NOAA-GFDL fremor

# equivalent syntax
conda install NOAA-GFDL::fremor

pip install source/checkout into a virtual environment (conda/venv)

If you're trying to develop fremor capabilities, or edit the code to your liking in either a big or small way, this is for you. This checks out the code, creates and activates an environment, installs into the environment, and runs all unit-tests and pylint checks:

# omit --recursive if you don't want tables as submodules
git clone --recursive https://github.com/NOAA-GFDL/fremor.git
cd fremor

# create an environment and install the local checkout
conda env create -f environment.yaml
conda activate fremor
pip install -e . 

# Run tests
pytest fremor/tests/

# Run linter
pylint --rcfile pylintrc fremor/

Usage

as a command line interface (CLI)

The CLI entry point is fremor, currently a suite of (currently) six routines for facilitating data preparation for CMIP7.

# The full list of subcommands
fremor init      # Initialize CMOR configuration resources: generate template user config, fetch tables
fremor find      # Find and print variables in MIP tables according to your variable lists or other input
fremor varlist   # Create a simple variable list of netCDF files in a directory
fremor config    # Generate a basic CMOR YAML configuration from a pp directory tree
fremor yaml      # Bulk routine for processing data based on a CMOR YAML config, calls fremor run many times
fremor run       # Lowest-level routine, no CMOR YAML needed, rewrites output files in a directory with CMOR

The CLI offers full logging and verbosity control independent of the command chosen:

# verbosity and logging
fremor -v  ...          # INFO level logging
fremor -vv ...          # DEBUG level logging
fremor -q  ...          # ERROR level only (quiet)
fremor -l mylog.txt ... # Log to file (appends)

If you've used the previous fre cmor command, there is a direct mapping of syntax:

# past fre-cli command
fre -vv -l logfile.txt cmor <COMMAND> [OPTIONS]

# fremor equivalent
fremor -vv -l logfile.txt <COMMAND> [OPTIONS]

as a python module

Each CLI subcommand (run, yaml, etc.) maps to an API under under fremor, so the CLI functionality is equivalently available via import in scripts as a proper python module

Getting started

For an overview of required inputs and sample commands, see the CMOR Quickstart.

CI/CD Workflows and QA

WCRP Compliance Checking (under development)

The wcrp_compliance_check workflow validates CMORized NetCDF outputs against WCRP project specifications using cc-plugin-wcrp, a plugin for the IOOS compliance-checker. This pipeline:

• Runs automatically on pull requests and via manual dispatch
• Executes unit tests to generate CMORized output files
• Gathers and categorizes outputs by CMIP version (CMIP6, CMIP7)
• Validates outputs using the wcrp_cmip6 compliance checker
• Uploads compliance reports as workflow artifacts (retained for 30 days)

To view compliance results from a workflow/CI run:

1. Navigate to the Actions tab in GitHub
2. Select the wcrp_compliance_check workflow run
3. Download the wcrp-compliance-reports artifact

License

Apache License 2.0 — see LICENSE.md

Releases and Versioning

fremor uses a post-release scheme to identify development beyond the latest tagged version and tie the current main branch to a conda package versioned as develop. To avoid confusion with fre-workflows and fre-cli, which often demand that the version tags match, fremor's version format is X.Y.Z[.post].

new published release procedure

To publish new release carefully follow the below procedure:

1. create a new branch off of main, which is already published to conda under develop/the previous tagged version + .post
2. edit the version number in fremor/_version.py from the current one, to the desired version tag, remove .post, then open a PR. edit nothing else (usually).
3. confirm the branch is functional by letting workflows finish, if you see green checks only, proceed. otherwise, stop and debug.
4. draft a new release pointing to the PR branch, click release. the publishing workflow should trigger and finish, and you should see the X.Y.Z version in the conda channel.
5. releases in this repository are immutable, so even if the release workflow fails, breathe and move on to the next step.
6. edit the version number in fremor/_version.py to X.Y.Z.post, and merge the PR to main workflow steps passed. publish_conda will trigger again and upload what is in main under the conda version develop and pip version X.Y.Z.post