This github-based fork of MONC is rapidly changing, with automated testing, docs, etc being set up

MONC is a highly scalable Large Eddy Simulation (LES) model that has been developed to simulate clouds and turbulent flows at high resolution (~ 10s of metres) on large domains. The MONC project was initially funded through a Joint Weather and Climate Research Program (JWCRP) enabling post via NERC research grant NE/L01338X/1, which facilitated a collaboration between Met Office scientists and computational scientists at EPCC to undertake the development of MONC.

The main aim of the MONC project was to develop a high resolution atmospheric process research model for the community that is user friendly and scalable on modern high performance computing (HPC) systems. The scientific basis for MONC is the Met Office Large Eddy Model (LEM) and the development involved the complete re-write of the Met Office LEM using modern software design with a flexible plug 'n play component based architecture with a focus on high performance computing (HPC) scaling and efficiency. '

Compiling and Running on Leeds ARC machines

To make compilation more simple on the ARC systems, a script called monc_compile_arc.sh has been written which loads the necessary modules and compiles MONC using fcm. A second script, submonc.sge, can be used to submit a MONC task using the command qsub submonc.sge and similarly loads the required modules before submitting the job.

MPI libraries and compilers on ARC

Testing has shown MONC to be incompatible with intel compilers at present (at the very least with intel 19.04), and so the compilation script uses the gnu compiler (version 4.8.5 by default on arc4, but tested and working with gcc 8.3.0 and gcc 6.3.0).

MONC has been known to sometimes have issues with openmpi, and so mvapich2 is recommended. Mvapich2 is incapable of running with multiple threads however, and testing has shown successful runs using all three MPI variants available on arc4 (openmpi, intelmpi and mvapich2) so while mvapich2 is the recommended variant, its use remains only a recommendation rather than a necessity.

Contributing

Note: Github have written their own guides on what git is and forking projects. A quick-start guide for working specifically with MONC follows below, see those for more detail.

To work on the MONC source code you'll first need your own copy:

1. Create your own fork on github.com of the main Leeds-MONC repository at https://github.com/Leeds-MONC/monc/fork

2. Clone your fork locally

   $> git clone https://github.com/{your-github-username}/monc

Then you can start work on your new feature/bug fix 🚀 and contribute it back to the main MONC repository:

3. Create your own branch or commit to master locally (remember you can do as many commits as you want, they are free and fast)

   $> git checkout -b cool-new-feature-for-monc
   (change files...)
   $> git add .
   $> git commit -m 'Add cool feature to MONC'

   ... (repeat git add and git commit as necessary)

4. Once your happy with your feature push it to github, check out and resolve any issues caught by the automated tests

   $> git push origin cool-new-feature-for-monc

5. Create a pull request on github.com to request that your change is included into master on the main fork at https://github.com/Leeds-MONC/monc

6. Resolve any issues/ask for review by the rest of the Leeds-MONC community on your pull request. Once ready, merge!

7. Celebrate 😃 🎉 🎊, and thank you for your hard work! ⭐

To make sure your fork is up-to-date with master (and master on your laptop) you'll need to add the main MONC repository as a "remote" that git knows about (the convention is to call this upstream) and "pull" down any changes:

8. Add the main repository as an upstream (if you don't already have it):

   $> git remote add upstream https://github.com/Leeds-MONC/monc

9. Pull in the changes to your local master branch (or any other branch where you want recent changes into)

   $> git pull upstream master

10. To update master on your fork on github you can now push the changes to there

    $> git push origin master

Keeping in sync with the Met Office Science Repository (MOSRS)

MOSRS uses SVN which can be used from git using git svn. The way this is done is to set up a svn-remote (pointing to a specific SVN path, for example trunk) and then fetching this content. Each commit on the MOSRS SVN will then have an corresponding git commit. Adding and accessing trunk from MOSRS can be done with the following commands:

export LOCAL_NAME="mosrs-trunk"
git config --add svn-remote.${LOCAL_NAME}.url https://code.metoffice.gov.uk/svn/monc/main/trunk
git config --add svn-remote.${LOCAL_NAME}.fetch :refs/remotes/mosrs/trunk
git svn fetch ${LOCAL_NAME}
git checkout remotes/mosrs/trunk -b ${LOCAL_NAME}
unset LOCAL_NAME

You will need a user account for MOSRS to be able to run this command. Once done the entire history of trunk on MOSRS will then be available on the git branch called mosrs-trunk, which can then be merged into the current branch.