Obtaining a GCHP Run Directory

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  1. Hardware and Software Requirements
  2. Downloading Source Code and Data Directories
  3. Obtaining a Run Directory
  4. Setting Up the GCHP Environment
  5. Compiling
  6. Running GCHP: Basics
  7. Running GCHP: Configuration
  8. Output Data
  9. Developing GCHP
  10. Run Configuration Files

Step 1: Create Run Directory

Navigate to the run/ subdirectory of the source code and create a run directory using shell script createRunDir.sh.

$ cd ~/GCHPctm/run
$ ./createRunDir.sh

During the course of script execution you will be asked a series of questions:

ExtData directory path

The first time you create a GCHP run directory on your system you will be prompted for a path to GEOS-Chem shared data directories. The path should include the name of your ExtData directory and should not contain symbolic links. The path you enter will be stored in file .geoschem/config in your home directory as environment variable GC_DATA_ROOT. If that file does not already exist it will be created for you. Once entered, you will not be prompted to enter it again. If the path changes in the future you must provide the new path in .geoschem/config. The run directory creation script will prompt you to do so only if the file is missing or if the paths within it are not valid.

Simulation type

You will next be prompted for what simulation you wish to create a run directory for.

Choose simulation type:
 1. TransportTracers
 2. Standard
 3. Benchmark

Enter the integer number next to the simulation type you want to use that is displayed on the screen.

Meteorology source

Next, choose which meteorology source you would like to use.

Choose meteorology source:
 1. MERRA2 (recommended)

Currently GCHP supports GEOS-FP and MERRA2 data only. Input data resolution is 0.25x0.325 for GEOS-FP and 0.5x0.625 for MERRA2 by default. Unlike GEOS-Chem Classic, GCHP input meteorology data does not need to be the same grid type or grid resolution as the grid and resolution you run at.

Storage location

Next, enter the target path where you want your run directory to be stored.

Enter path where the run directory will be created:

Do not include symbolic links in the path. Choose your path wisely to keep your runs organized.

Run directory name

You will then be prompted to enter a run directory name if you did not pass one as an optional argument when calling the script. You are given the option to simply press return and use the default run directory name of format gchp_{simulation_type}. Here is an example of what you will see if using the default name for the standard full chemistry simulation:

Enter run directory name, or press return to use default:

Using default directory name gchp_standard

Run directory version control

Finally, you will be asked if you want to track run directory changes with git version control. This feature is useful if you plan on making feature updates to GEOS-Chem that involve changes to the run directory, such as adding emissions or turning components on or off. With version control you can keep track of exactly what you changed relative to the original settings.

This is what you will see if you use to put your run directory under version control with git:

Do you want to track run directory changes with git? (y/n)
Initialized empty Git repository in /n/home/user003/gchp_standard/.git/

We strongly recommend using this feature if you plan on submitting an update for inclusion in the standard model since you can copy changes directly from your version history to GCHP/Run, and then commit those changes with your source code updates. If you forked the repository you can then push to your fork and do a pull request to send us your updates.

Step 2: Set Environment

Set the gchp.env symbolic link to your GCHP environment file using shell script setEnvironment.

cd /home/gchp_fullchem
./setEnvironment /home/envs/gchp_ifort19_openmpi4.env


  • You can keep your environment file anywhere on your system for reuse across multiple run directories.
  • Always source gchp.env prior to building and running GCHP.
  • Include source gchp.env at the top of your run scripts.

Additional information

A new run directory should be created for each different version of GEOS-Chem you use. Version information per run directory is located in file rundir.version.

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