Makkink forcing will use excessive memory with default ESMValTool dask.yml

[BSchilperoort]

When running the Makkink forcing generation for ERA5 for a range of a couple of years, it can use excessive memory causing the kernel to crash.

However, when defining ~/.esmvaltool/dask.yml as the following:

cluster:
  type: distributed.LocalCluster
  n_workers: 2
  threads_per_worker: 1
  memory_limit: 5 GiB

It runs fine with a memory use <2GB.

The issue probably occurs in the post-processing function where the potential evaporation is computed. However, we do run into conflicting advice:

• Dask recommends using the distributed scheduler.
• ESMValTool recommends the local sheduler as not all iris (and ESMF...) functionality works well with Dask Distributed.