How to build a new ACCESS-ESM executable

How to build a new ACCESS-ESM executable#

Situation#

A student has come to me because they need executables for the ACCESS-ESM model with changed orbital parameters. They call the experiment ‘8.2ka_event’

Here’s the list of orbital parameters they need:

Parameter	Value
eccentricity	0.019199
obliquity	24.222° x pi/180
perihelion-180°	319.495° x pi/180
Date of vernal equinox	Mar 21st noon
Time of perihelion passage in days	218.05

Step 1: Check out the build environment#

In a suitable directory, preferably on /scratch on gadi, run the commands:

# Clone the repository for the build environment
git clone https://github.com/coecms/access-esm-build-gadi.git
cd access-esm-build-gadi
# Create a new branch to ensure that changes don't go back up
git checkout -b '8.2ka_event'

Step 2: Make a copy of the UM sources since we need to modify them#

You can check the location of the UM repositories in the Makefile, but we need to now make a copy of it:

svn cp \
file:///g/data/access/access-svn/cmip5/branches/dev/jxs599/trunk_ESM1.5 \
file:///g/data/access/access-svn/cmip5/branches/dev/hxw599/8.2ka_event \
-m 'create branch for 8.2ka event experiment'

Here, the target branch contains my username (hxw599) and a proper name (8.2ka_event). You will have to use your own values for that.

We also need to change these values in the Makefile.

vim Makefile

Edit line 6 from

SUBMODELS_REPO=file:///g/data/access/access-svn/cmip5/branches/dev/jxs599/trunk_ESM1.5/submodels

to

SUBMODELS_REPO=file:///g/data/access/access-svn/cmip5/branches/dev/hxw599/8.2ka_event/submodels

Then we need to check out the sources:

make src/UM

(If we want to modify other submodels, we would need to check them out, but the orbital parameters only affect the UM.)

Step 3: Make the modification to the source code#

In this case the code modifications are quite minimal. There are just a few constants to change in a singe file.

cd src/UM
vim umbase_hg3/src/include/constant/astron.h

Then check in the changes:

svn ci -m 'change orbital parameters for 8.2ka experiment'
cd ../..

Step 4: Make the executables#

In the directory that was created in the Step 1, run the command

make

This will check out all the sources that haven’t yet been checked out and compile the three executables. It will take a while.

Step 5: Move the executables to where they can be used.#

To keep some indications on which version of the UM source code the binary is based, I like to add the revision number to the file name.

cd src/UM
svn up
Updating '.'
At revision 795
cd ../../bin
mv um_hg3.exe-20230808 um_hg3.exe-r795-20230808

Ensure that the binaries are copied to where they are safe from /scratch’s auto-removal. I’m copying them to a subdirectory on /g/data/access:

cp * /g/data/access/payu/access-esm/bin/coe/8.2ka/
chown -R $USER:access /g/data/access/payu/access-esm/bin/coe/8.2ka

And now the new executables are available for general use.