[MITgcm-support] restart from pickup files (cube-sphere)

[Dimitris Menemenlis]

Yuan, any time order of operations change, you can expect some differences at 
the numerical precision level, which can grow over time depending on resolution.

Changing SIZE.h should be sufficient when going from 12 to 6 CPUs.  You just 
need to make sure that the product nSx * nPx remains unchanged, for example, if 
you 12-CPU job has:
      &           nSx =   1,
      &           nPx =  12,
you can convert it to a 6-CPU job with
      &           nSx =   2,
      &           nPx =   6,