Parallel I/O

The model can be told to write a different output file per process. This may or may not save time, and is a bad idea on Lustre filesystems. If the model is writing individual files per process, one can combine them using the mppnccombine program from the \href{https://github.com/NOAA-GFDL/FRE-NCtools}{\texttt{ F\+R\+E-\/nctools package}}. 