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This repository includes the public release of the GFDL AM4 modelcode. The AM4 model is described in thetwoarticles published in theJournal of Advances in Modeling Earth Systems(JAMES).More information on the model and access to the output is available ontheAM4 data and codesite at theGeophysical Fluid Dynamics Laboratory(GFDL).

The layout of this package includes the following directories:

• src - The source code for the AM4 model
• exec - The build directory with Makefiles for building the AM4 model executable
• idealized_exec - The build directory with Makefiles for building the aquaplanetand doubly periodic executable
• run - Sample run script and updated files needed for running
• analysis - Sample analysis scripts

This repository usesgitsubmodules topoint to other repositories. Thus, care should be taken when cloning,and updating the source to ensure all source. To obtain all source,use the following git command

git clone --recursive https://github.com/NOAA-GFDL/AM4.git

The--recursive option togit clone instructs git to recursivelyclone all submodules. In the event the repository was not clonedusing the--recursive option, the following step must be taken toobtain all sources:

# From within the AM4 parent directorygit submodule update --init --recursive

All model source is contained in thesrc directory. GFDLtracks code using the git version control system. This packageincludes a single version of the following GFDL model components. Thegit hash listed corresponds to the commit hash in the internal GFDLgit repository.

The following components are available in theNOAA-GFDL github organization:

• MOM6
• coupler
• FMS (asshared)
• GFDL_atmos_cubed_sphere (tag AM4.0) (asatmos_cubed_sphere)

###ContainersThecontainer folder provides example Dockerfiles and Signularitydefinition files to use to build AM4 containers using either GCC/GFORTAN orIntel oneAPI. There is a script that can be used to build the intelsingularity containers, and the first step of this script can be used with theother GFDL climate models.

Theexec directory contains Makefiles that can be used tobuild the AM4 executable. These Makefiles were generated using theMake Makefile (mkmf) program.Included in the exec direcgtory is a sample make template file for theIntel compilers (intel.mk). This maketemplate can be used on any system with a relatively recent version ofthe Intel compilers, the netCDF 4 library and the MPICH2 MPI library.Included in theintel.mk file areadditional settings that can be modified during the build.

To run the default build (-O3 -msse2), go to the exec directory andenter the command

make

If you would like to change some of the compiler options, there are several differentoptions to add to the make command. For example

make ISA=-xhost BLD_TYPE=REPRO

will replace -msse with -xhost and -O3 with -O2. The three options forBLD_TYPE are
PROD (-O3)
REPRO (-O2)
DEBUG (-O0 and other traps)
All of the make line options can befound in theintel.mk file.

The input data required for running the AM4 model can be found onGFDL's dataportal .

The fileAM4.tar.gz contains a configured run directory to run asample experiment of the AM4 model. Included in the tar file is aREADME.AM4_run with more instructions on how to configure the AM4 rundirectory.

On Linux systems, thewget command is usually sufficient to download the datafile:

wget ftp://nomads.gfdl.noaa.gov/users/Ming.Zhao/AM4Documentation/GFDL-AM4.0/inputData/AM4_run.tar.gz

To ensure the file downloaded is complete and not corrupted, download one of the two files:

wget ftp://nomads.gfdl.noaa.gov/users/Ming.Zhao/AM4Documentation/GFDL-AM4.0/inputData/AM4_run.tar.gz.sha256wget ftp://nomads.gfdl.noaa.gov/users/Ming.Zhao/AM4Documentation/GFDL-AM4.0/inputData/AM4_run.tar.gz.sig

and run the following command that corresponds to the signature file downloaded:

sha256sum -c AM4_run.tar.gz.sha256

gpg --verify AM4_run.tar.gz.sig

Included in the run directory is a sample run script for reference.To run the AM4 sample experiment, first download the data filementioned inObtaining the Input datasection. Replace diag_table and input.nml in the top level of theuntar'd directory with the corresponding files in the run directoryof this repository. Modify the variables in the configuration sectionin the sample run script, and then run the script.

The sample data and run script are configured to run on 216processors. To run on a different number of processors, or modify theexperiment, refer to theREADME.AM4_run file included in the AM4data tarball.

Note: Theinput.nml file (found in the AM4 data tarball) containsFortran namelists and namelist variables that modify, at run time, themodel. To learn more about the settings in theinput.nml file,please refer to source code where the namelist/variable are defined.

Some of the climate analysis scripts run at NOAA GFDL and used in theAM4 documentation papers are located in the analysis directory.Within each analysis suite, is ajupyternotebook, bothreadable and runnable from your local jupyter environment, providedall dependencies are installed.

E.g.

• Radiation processor
• Long-term DJF seasonal mean
• Zonal_mean_zonal_wind_stress
• PCMDI Metrics Portrait Plot

Please refer to theAM4 data and codesite for detailsabout where to find model and OBS data used in the papers.

For all analysis figures and pertaining data, please use the AM4documentation papers as the original reference.

Please direct your questions and feedback togfdl.climate.model.info@noaa.gov

The United States Department of Commerce (DOC) GitHub project code isprovided on an 'as is' basis and the user assumes responsibility forits use. DOC has relinquished control of the information and nolonger has responsibility to protect the integrity, confidentiality,or availability of the information. Any claims against the Departmentof Commerce stemming from the use of its GitHub project will begoverned by all applicable Federal law. Any reference to specificcommercial products, processes, or services by service mark,trademark, manufacturer, or otherwise, does not constitute or implytheir endorsement, recommendation or favoring by the Department ofCommerce. The Department of Commerce seal and logo, or the seal andlogo of a DOC bureau, shall not be used in any manner to implyendorsement of any commercial product or activity by DOC or the UnitedStates Government.

This project code is made available through GitHub but is managed byNOAA-GFDL athttps://gitlab.gfdl.noaa.gov.