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Change","sub_category":"Earth and Climate Modeling","monthly_downloads":0,"total_dependent_repos":0,"total_dependent_packages":0,"readme":"==================================\n The Community Earth System Model\n==================================\n\nSee the CESM web site for documentation and information:\n\nhttp://www.cesm.ucar.edu\n\nThe CESM Quickstart Guide is available at:\n\nhttp://escomp.github.io/cesm\n\nThis repository provides tools for managing the external components that\nmake up a CESM tag - alpha, beta and release. CESM tag creation should\nbe coordinated through CSEG at NCAR.\n\nThis repository is also connected to slack at http://cesm2.slack.com\n\n.. sectnum::\n\n.. contents::\n\nSoftware requirements\n=====================\n\nSoftware requirements for installing, building and running CESM\n---------------------------------------------------------------\n\nInstalling, building and running CESM requires:\n\n* a Unix-like operating system (Linux, AIX, OS X, etc.)\n\n* git client version 1.8 or newer\n\n* python3 version 3.8 or newer\n\n* perl version 5\n\n* build tools gmake and cmake\n\n* Fortran and C compilers\n\n  * See `Details on Fortran compiler versions`_ below for more information\n\n* LAPACK and BLAS libraries\n\n* a NetCDF library version 4.3 or newer built with the same compiler you\n  will use for CESM\n\n  * a PnetCDF library is optional, but recommended\n\n* a functioning MPI environment (unless you plan to run on a single core\n  with the CIME mpi-serial library)\n\nDetails on Fortran compiler versions\n------------------------------------\nThe Fortran compiler must support Fortran 2003 features. However, even\namong mainstream Fortran compilers that claim to support Fortran 2003,\nwe have found numerous bugs. Thus, many compiler versions do *not* build\nor run CESM properly (see\nhttps://wiki.ucar.edu/display/ccsm/Fortran+Compiler+Bug+List for more\ndetails on older Fortran compiler versions).\n\nCESM2 is tested on several different systems with newer Fortran compilers:\nPlease see `CESM Compiler/Machine Tests \u003chttps://docs.google.com/spreadsheets/d/15QUqsXD1Z0K_rYNTlykBvjTRt8s0XcQw0cfAj9DZbj0/edit#gid=0\u003e`_\nfor a spreadsheet of the current results.\n\nMore details on porting CESM\n----------------------------\n\nFor more details on porting CESM to a new machine, see\nhttp://esmci.github.io/cime/versions/master/html/users_guide/porting-cime.html\n\nObtaining the full model code and associated scripting infrastructure\n=====================================================================\n\nCESM is now released via github. You will need some familiarity with git in order\nto modify the code and commit these changes. However, to simply checkout and run the\ncode, no git knowledge is required other than what is documented in the following steps.\n\nTo obtain the CESM code you need to do the following:\n\n#. Clone the repository. ::\n\n      git clone https://github.com/escomp/cesm.git my_cesm_sandbox\n\n   This will create a directory ``my_cesm_sandbox/`` in your current working directory.\n\n#. Go into the newly created CESM repository and determine what version of CESM you want.\n   To see what cesm tags are available, simply issue the **git tag** command. ::\n\n      cd my_cesm_sandbox\n      git tag\n\n#. Do a git checkout of the tag you want. If you want to checkout cesm3_0_beta02, you would issue the following. ::\n\n      git checkout cesm3_0_beta02\n\n   (It is normal and expected to get a message about being in 'detached\n   HEAD' state. For now you can ignore this, but it becomes important if\n   you want to make changes to your Externals.cfg file and commit those\n   changes to a branch.)\n\n#. Run the script **bin/git-fleximod update**. ::\n\n      ./bin/git-fleximod update\n\n   The **git fleximod** script is a git extension that will\n   populate the cesm directory with the relevant versions of each of the\n   components along with the CIME infrastructure code.\n\nAt this point you have a working version of CESM.\n\nTo see full details of how to set up a case, compile and run, see the CIME documentation at http://esmci.github.io/cime/ .\n\nMore details on git fleximod\n----------------------------------\n\nThe file **.gitmodules** in your top-level CESM directory tells\n**git fleximod** which tag/branch of each component should be\nbrought in to generate your sandbox.\n\nNOTE: git fleximod will always attempt\nto make the working copy exactly match the externals description. For\nexample, if you manually modify an external without updating .gitmodules,\n(e.g. switch to a different tag), then rerunning git fleximod\nwill warn you and can restore the original version by using the --force option\nbelow documentation `Customizing your CESM sandbox`_ for more details.\n\n**You need to rerun git-fleximod update whenever .gitmodules has\nchanged** (unless you have already manually updated the relevant\nexternal(s) to have the correct branch/tag checked out). Common times\nwhen this is needed are:\n\n* After checking out a new CESM branch/tag\n\n* After merging some other CESM branch/tag into your currently\n  checked-out branch\n\nTo see more details of **git-fleximod**, issue ::\n\n  ./bin/git-fleximod --help\n\nCustomizing your CESM sandbox\n=============================\n\nThere are several use cases to consider when you want to customize or modify your CESM sandbox.\n\nSwitching to a different CESM tag\n---------------------------------\n\nIf you have already checked out a tag and **HAVE NOT MADE ANY\nMODIFICATIONS** it is simple to change your sandbox. Say that you\nchecked out cesm3_0_beta01 but really wanted to have cesm3_0_beta02\nyou would simply do the following::\n\n  git checkout cesm3_0_beta02\n  ./bin/git-fleximod update\n\nYou should **not** use this method if you have any ongoing CESM cases that were created from\nthis sandbox. In these cases, it is often easiest to do a second **git\nclone**.\n\nPointing to a different version of a component\n----------------------------------------------\n\nEach entry in **.gitmodules** has the following form (we use CAM as an\nexample below)::\n\n  [submodule \"cam\"]\n    path = components/cam\n    url = https://www.github.com/ESCOMP/CAM\n    fxDONOTUSEurl = https://www.github.com/ESCOMP/CAM\n    fxtag = cam6_4_016\n    fxrequired = ToplevelRequired\n\nEach entry specifies either a tag or a hash. To point to a new tag:\n\n#. Modify the relevant fxtag entry/entries in **.gitmodules** (e.g., changing\n   ``cam6_4_016`` to ``cam6_4_017`` above)\n\n#. Checkout the new component(s)::\n\n     ./bin/git-fleximod update cam\n\nKeep in mind that changing individual components from a tag may result\nin an invalid model (won't compile, won't run, not scientifically\nmeaningful) and is unsupported.\n\nCommitting your change to .gitmodules\n~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n\nAfter making this change, it's a good idea to commit the change in your\nlocal CESM git repository. First create a CESM branch in your local\nrepository, then commit it.  For example::\n\n  git checkout -b my_cesm_branch\n  git add .gitmodules components/cam\n  git commit -m \"Update CAM to cam5_4_144\"\n\nModifying a component\n---------------------\n\nIf you'd like to modify a component via a branch and point to that\nbranch in your CESM sandbox, use the following procedure (again, using\nCAM as an example):\n\n#. Create a CAM branch. Let's assume you have created this branch and called it\n   **my_branch**.\n\n#. Update **.gitmodules** to point to a hash on your branch. You can replace the\n   **tag** entry with a **hash** entry, as follows, note that we have also changed the url to\n   point to a personal fork::\n\n    [submodule \"cam\"]\n      path = components/cam\n      url = https://www.github.com/mycamfork/CAM\n      fxDONOTUSEurl = https://www.github.com/ESCOMP/CAM\n      fxtag = 94eaf83\n      fxrequired = ToplevelRequired\n\n\n#. Checkout your branch::\n\n     ./bin/git-fleximod update cam\n\nIt's a good idea to commit your **.gitmodules** file changes. See the above\ndocumentation, `Committing your change to .gitmodules`_.\n\nDeveloper setup\n===============\n\nDevelopers who have not already done so should follow the recommended\n`one-time \u003chttps://github.com/esmci/cime/wiki/CIME-Git-Workflow#configure-git-one-time\u003e`_\nsetup directions for git. Developers may also want to set up\n`ssh \u003chttps://help.github.com/articles/connecting-to-github-with-ssh/\u003e`_\nkeys and switch to using the ``git@github.com:ESCOMP/cesm.git`` form of the github URLs.\n","funding_links":[],"readme_doi_urls":[],"works":{},"citation_counts":{},"total_citations":0,"keywords_from_contributors":["climate-science","e3sm","snl-applications","cesm","earth-system-model","datamodeling","land-surface-model","land","hydrology","ecosystem"],"project_url":"https://ost.ecosyste.ms/api/v1/projects/76723","html_url":"https://ost.ecosyste.ms/projects/76723"}