Hi-res support on Perlmutter

Follow-up to #310.

`docs/source/campaigns.rst`: access to "bigmem nodes on NERSC Cori" required

https://docs.nersc.gov/systems/perlmutter/architecture/#large-memory-nodes: "These nodes are not yet available for user jobs."

So, that effectively means we can't run hi-res until Perlmutter large memory nodes become available. Also, they have "1 TB of memory" compared to the "2 TB of RAM" on Cori's large memory nodes (https://docs.nersc.gov/systems/cori-largemem/).

Read issue #310 and docs/source/campaigns.rst, then verify the linked NERSC Perlmutter architecture page for large-memory-node availability. The issue is done only when hi-res processing can be run on Perlmutter; until then, the work is blocked by the unavailable large-memory nodes.

Written by the indexing model from the issue text.