The ECMWF OpenIFS model has become publicly available for download under the Apache 2.0 open-source licence. This page provides an overview how to work with the new git repository on GitHub.
Download the OpenIFS model
The source code for the OpenIFS model, inclusive of the OpenIFS single-column model and the latest documentation, can be downloaded free from this repository on GitHub:
https://github.com/ecmwf-ifs/openifs
Migration for existing users
Users of previous OpenIFS releases (also including OpenIFS 48r1) should note that only the release available on GitHub is distributed under the open-source Apache 2.0 licence.
Any previous releases of OpenIFS (obtained from the download site, ftp server, or the ECMWF Bitbucket git repository) does not meet the open-source criteria, as agreed between ECMWF and Meteo-France, and therefore the usage of these previously released source codes is only permitted under the conditions of the old ECMWF OpenIFS software licence.
Please note that the git merge of earlier model developments into the new open-source git repository may result in the inclusion of older git history which is not part of the open-source release. Such an inclusion into the git history will void the open-source licence of the resulting code package. Therefore we strongly recommend to carry out a "clean start" and manually implement any earlier code changes without merging in older git commits.
ECMWF will no longer offer any support for the earlier non-open source OpenIFS model releases.
In order to benefit from the latest model developments, upgrades and new model cycles, including the benefits of the open-source licence, all model users are strongly encouraged to upgrade to the new open-source release as soon as possible.
Branching and Tagging Convention
Branch Naming
openifs-<support-level>/CY<cycle-number>.<dot-release>
Example: openifs-lts/CY48R1.1
<support-level>
The first indication of support length:
- lts - Long-term support, defined by the IFS cycle support time. These cycles often relate to cycles used for ERA or, for example, the cycle that forms part of EC-Earth4 (e.g., 48R1.1).
- mts - Medium-term support (normally 2 years after release).
- deprecated - Branch no longer supported because, for example, it is out of the support period or the code has been superseded.
- unsupported - Not all IFS cycles will be formally released as OpenIFS. The code and ifs-test will be made available, but initial conditions from the datahub for that cycle are not guaranteed.
<cycle-number>
The IFS cycle number (e.g., 48R1, 49R1). These cycle numbers generally relate to operational cycles, with the exception being cycles for ERA.
<dot-release>
A number to identify a scientifically stable, bit-comparable release (e.g., 48R1.0, 48R1.1). A change in the dot-release number signifies a change in scientific answers. It is important to note that the dot-release number should relate to an IFS dot-release.
Tag Naming
openifs-<cycle-number>.<dot-release>.<version>
Example: openifs-48r1.1.0
<cycle-number> and <dot-release>
As defined for the branch naming, except the cycle name is lower-case to match previous openifs naming convention.
<version>
Represents a change to OpenIFS that is scientifically bit-comparable, e.g., bit-comparable bug fixes or changes to the scripts. If a change leads to a change in scientific output, then the dot-release number will increase.
Documentation on GitHub
The latest documentation for OpenIFS is included in the git repository, in the README.md and in the docs directory.
This documentation supersedes the existing user guides on ECMWF Confluence which will no longer be maintained. This also ensures that the documentation remains aligned with the respective model version.
