Add build notes

Author: zmoon

01-setup.md

@@ -2,3 +2,90 @@
 title: Build
 subtitle: Building MPAS on NSF NCAR Derecho
 ---
+
+It's good practice to compile the model in an interactive job,
+to avoid stressing the login nodes,
+_and_ to ensure that nodes detected at build time are the same as those used at run time[^derecho-nodes].
+
+[^derecho-nodes]:
+    On Derecho, the login nodes have the
+    [same processors](https://ncar-hpc-docs.readthedocs.io/en/latest/compute-systems/derecho/#derecho-hardware)
+    as the compute nodes, but this is not always the case on other systems.
+
+```bash
+qsub -I -l walltime=3600 -l select=1:ncpus=4:mem=80gb -A UTAM0025 -q develop
+```
+
+After our session starts, we need to load some modules.
+
+::::{tab-set}
+
+:::{tab-item} Intel 2023
+
+```{code} bash
+:filename: modules-intel-2023.sh
+:caption: These are the modules we've used for the referenced papers.
+
+# NCAR Derecho modules for MPAS-A
+# `source` or `.` this file to use
+
+module --force purge
+module load ncarenv/23.06
+module load intel/2023.0.0
+module load cray-mpich/8.1.25
+module load parallel-netcdf/1.12.3
+
+# Hack to get pnetcdf working again
+export LD_LIBRARY_PATH="/glade/u/apps/derecho/23.06/spack/opt/spack/parallel-netcdf/1.12.3/cray-mpich/8.1.25/oneapi/2023.0.0/blyr/lib:$LD_LIBRARY_PATH"
+```
+
+:::
+
+:::{tab-item} Intel 2025
+
+```{code} bash
+:filename: modules-intel-2025.sh
+:caption: Updated modules, using `ifx` instead of `ifort`.
+
+# NCAR Derecho modules for MPAS-A
+# `source` or `.` this file to use
+
+module --force purge
+module load ncarenv/24.12
+module load intel/2025.1.0
+module load cray-mpich/8.1.29
+module load parallel-netcdf/1.14.0
+
+# Tell mpifort to use ifx
+export MPICH_FC=ifx
+```
+
+:::
+
+::::
+
+```{tip}
+NCAR also [provides](https://ncar-hpc-docs.readthedocs.io/en/latest/pbs/)
+`qcmd` and `qinteractive` shortcut commands that you can use,
+but the above `qsub` should work on other PBS-based systems as well.
+
+The [`develop` queue](https://ncar-hpc-docs.readthedocs.io/en/latest/pbs/charging/#derecho-queues)
+has a 6-hour walltime limit and is intended for testing and development.
+Above we have requested 3600 seconds (1 hour).
+```
+
+First we build the model initialization program.
+This is what we use to generate initial conditions and such.
+
+```bash
+make -j4 intel CORE=init_atmosphere
+```
+
+Now, assuming the `init_atmosphere_model` executable was built successfully,
+we can build the main program.
+
+```bash
+make -j4 intel CORE=atmosphere
+```
+
+If this completes successfully, we should have an `atmosphere_model` executable.