Getting Started with EC-Earth 4

EC-Earth 4 is provided as a set of sources that contains other upstream projects such as OpenIFS and Nemo. To use EC-Earth 4, you will have to get access to the source code. If you also want to develop it, you will need further interaction with the development platform.

In this getting started guide, we will show you the steps needed to start using the model.

The development platform used for EC-Earth 4 is an installation of the Gitlab platform hosted at SMHI. If you are familiar with Github, Gitlab, or Bitbucket, you will feel immediately at home. If not, don’t worry, we’ll show you everything you need. If you have any questions or need assistance, you will soon learn about all the ways that you can ask for it.

But first we need to get you access to the platform.

Getting access to the development platform

Registering an account

The EC-Earth 4 source code is hosted at SMHI. To get access to it, you must first create an account on the development platform, and then join the EC-Earth group.

To create the account, please fill in this form. You will then receive an invitation email with further instructions.

A TOTP (time-based one-time-password) will be required to login to the SMHI GitLab portal every time. This is a requirement and only one device can be setup at the same time. If your device changes, you can change the TOTP for your account by sending a message to servicedesk@smhi.se and ask them to delete the old TOTP. On a new login, you will be asked to setup the new device.

Joining the EC-Earth group

With your newly created account, you can now login to the development platform using the same web page https://git.smhi.se. However, you will still not be able to access the EC-Earth source code. Because the source code is not open source software, there is another layer of protection that allows us to manage the access in line with the licensing requirements.

Note

In order to get access, you must be eligible. Currently, the conditions are that your institute must be a member of the EC-Earth consortium and must have an OpenIFS license.

To get access, go to the EC-Earth group by following the link https://git.smhi.se/ec-earth. You will reach the web page shown in Fig. 1.

Fig. 1 This is the EC-Earth group page before you have access. To request access to the group and the EC-Earth source code, click on the Request access link highlighted here.

By clicking on the Request access link, you will notify the user management team that you would like to join EC-Earth. They will have a look and enable your account within a few days.

Note

Once you are logged in to the platform, you can get help and information about the features of the platform, such as issues, merge request, and notifications, from the help menu available in the top right corner (the little question mark inside a circle). Next to it you will find your profile menu.

Getting the source code

To download the source code, you must use Git. If you are working on a High Performance Computer (HPC), chances are that you have it already available to you.

Note

Without further configuration, you will have to enter your password many times, which can become tedious. To avoid this, now may be a good time to follow the advice at Avoid repeating your password.

When you use git to download a project such as EC-Earth, it will create a new folder to contain it. Decide where you want to place the source code and open a shell there.

git clone -o upstream --recurse-submodules https://git.smhi.se/ec-earth/ecearth4.git

This will create a new directory, ecearth4, that contains the most recent source code for EC-Earth 4, including all components such as Nemo and OpenIFS.

Hint

Cloning the repository with submodules can take some time. In particular, getting the OASIS submodule takes longer than it should because there are some very large files in the Git history of the repository. There is a trick that avoids downloading very large files, namely adding the options --filter=blob:limit=500m --also-filter-submodules to the git clone command above. This will not download any files in any submodule that is bigger than 500 MB (which could be set to any other value). It is therefore recommended to use these options with caution and only when really needed.

Congratulations, you are all set up. Now head over to the next section, which describes how to compile the EC-Earth 4 source code.