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For Beginners

[Information and Communication][Structure of the community][First steps][User support ]

Welcome to the CLM-community!

This page contains specific information which (hopefully) helps you having a good start with the COSMO-CLM model and in the CLM-community.

Note that, besides this web page, there is a second web area with more technical content (e.g. source codes, bug tracking system and the community forum). This is the RedC (Redmine for model development and dissemination in the CLM-Community) web site:
Login and passwort are the same as for the CLM-community web site.

Below, you will find some detailed information about:

1)    Information and Communication
2)    Structure of the community
3)    First steps with the COSMO-CLM model
4)    User support  

Information and Communication

The official language of the CLM-Community is English.

The main source of information is the CLM-Community homepage Please, make use of the homepage and help to keep this homepage up-to-date. An additional source of information is the COSMO homepage

The information given in the application form, the presentations at and the results of meetings are made available for CLM-Community members only. If you login as member, you find a lot of information about the work and the plans of other members of the community. This gives you the opportunity to use the experience, software and the results of other colleagues as stated in the community agreement.

Part of the communication in the CLM-Community is done through mailing lists. The main list contains all members of the community. In addition, special mailing lists exist for each working and project group and for the different community bodies. All members of the clm_user mailing list and some members of cosmo are allowed to send emails to all mailing lists.
If you want to obtain more information on the mailing list system, please send an email to with the following text
   info refcard
You will receive an email containing the main instructions.

After publication of results obtained with the COSMO-CLM model, the references and a copy of all relevant publications (peer-reviewed articles as well as theses, etc.) should be send to the coordination office. The references and, if possible, the publications themselves will be made available on the CLM-Community homepage " -> Publications“.

Structure of the community

Working groups

The common tasks and interests around the usage and further development of the model system are coordinated and conducted in different working groups (WG). Additionally, some project groups (PG) exist where specific tasks are handled for a limited time range. The existing groups and projects are listed here. All community members are encouraged to join one or several of these groups: please indicate your interest to the coordination office or directly to the WG/PG coordinators.  Each WG and PG has an own mailing list. Only members of the WGs are members of the mailing list and get respective mails.

Research Overview / Topic browser

An overview of all research subjects conducted in the community can be found in the topic browser: “ -> Community -> Science”. According to the community regulations, all members should provide information about their current work with COSMO-CLM. As a new member, please check if the current entry on your topic in the browser is correct. In addition, please, use regularly (about once a year) the opportunity to update the research topic description. You can do this by selecting the update button right of the description of your topic. Note, that the form for advanced users does contain more information helpful for searching collaborators.


As a member of the community, we ask you to stick to a few rules in order to achieve the common goal of improving the model system and to facilitate the exchange between community members.
In particular, please

•    attend the CLM-Community Assembly and other CLM-Community meetings and workshops. Have a look at the articles under menue Events for the upcoming meetings,
•    use CLM-Community released (positively evaluated) model versions and configurations for production runs (and publications) only,
•    save all information necessary to reproduce your simulations and results: the external data produced by webPEP including the settings for EXTPAR, the scripts and configuration files used to run the INT2LM and COSMO-CLM, the compiled versions of INT2LM and COSMO-CLM, in case you used own model modifications cource codes, the COSMO-CLM input, if it is not part of an official database, and the COSMO-CLM output.

Rules of collaboration within the community are coded in the documents made available on the webpage " -> Community -> Terms & Conditions”. Please, read the CLM-Community agreement carefully. It is the main document describing the collaboration within the community.

More information about bodies and members of the community can be found under the “community” menue of the web page.

First steps with the COSMO-CLM model

Starter package

To get familiar with the model system, a starter package contains everything to run a CCLM simulation (model source code, sample scripts, sample data, short documentation). It is available via the RedC (Redmine for model development and dissemination in the CLM-Community) web site in the project 'CCLM Starter Package' (

Training / Tutorial

It is recommended to attend the COSMO/CLM/ART Training Course, which takes place once a year in February/March in Langen near Frankfurt/M., Germany. Within the COSMO/CLM/ART Training materials, a tutorial is available. This tutorial might also be helpful to those who are not able to attend the Training Course.

Source code availability

The positively evaluated versions of the COSMO-CLM model are made available on the RedC page (e.g.  for the CCLM, and in the respective “Projects” area for the other parts of the model system). These versions are the "released" model versions and configurations. Other model versions are for the developers and testers only.

Initial and boundary conditions

The COSMO-CLM model needs initial and boundary data from a global model (or reanalysis) and external parameters on the simulation grid as input.
Three steps are necessary to prepare the data:
1.    Conversion of the driving model data to INT2LM input conform netCDF format (“prepreprocessor”; for some models, such converter programs are available )
For some input data, this step has already been made and the INT2LM-ready data are provided at the DKRZ computers. A list of available data can be found here
2.    Processing of the external parameters for interpolation of the physical properties of the region and the vegetation to the grid of the COSMO-CLM. This program is called “EXTPAR” (External Parameter for Numerical Weather Prediction and Climate Application). A web-based version (called WebPEP) is available using the standard input data.

3.    Finally the interpolation program INT2LM calculates the initial and boundary conditions using the EXTPAR results and interpolating the coarse grid model fields to the COSMO-CLM grid.

Run and Compile environment

If you don’t have your own run and compile environment available at your institute, you can use the run and compile environment “subchain” which is available for the model version used at the COSMO-CLM training. "subchain" is part of the starter package and information on the training web page.

Model configuration

The settings of model parameters defining the model grid, physics, dynamics and numerics used in the simulation are defined in Fortran namelists. For an overview of the meaning of the parameters included in the namelists and for some standard settings, please use the Namelist-Tool-Portal and read the COSMO User’s Guide.


The main scientific documentations of the COSMO model are available from the COSMO web page:
Additional information can be found on the CLM-Community webpage " -> Model -> Documentation”.

User support

The user support is provided by the CLM-Community working group SUPTECH.

The RedC page ( contains all source code information and the CLM-Community forum.

In case of problems, please post your questions in the CLM-Community forum. Please include all information necessary to understand your problem (you can also upload files such as the error report, the YUSPECIF file showing your model configuration or plots of the output).

To report bugs in the model code, a "developer" has to fill out the “New issue” form for the respective Project (i.e. part of the model system) on the RedC page. It has to be sure, that a bug is found and not only a problem occured. Before a bug is reported the issue should be discussed in the forum. Developers are listed on the RedC page -> Projects.

Several utilities are available which can be used by all community members, such as a Namelist Tool, a starter package or some postprocessing software (list of these utilities).

In case of questions related to the community membership, please contact the coordination office.