[MITgcm-support] shapiro filter on partial domain

[William Boos]

I am running a 2D (latitude-height) version of the mitgcm, atmospheric
version, with a land surface covering part of the domain.  I have found it
is necessary to shapiro filter the land surface temperature to eliminate
instability due to 2-gridpoint waves in this field.  However, when I do this
I get an instability in the 2 to 3 land grid cells adjacent to the ocean.  I
am guessing that this occurs when the shapiro filter tries to act on the
surface temperature discontinuity which arises between ocean and land
gridpoints (the ocean is held at fixed SST).

How can I run the shapiro filer on the land surface only, specifying the
appropriate horizontal boundary conditions at the coast?  Or is there some
other solution to this situation?

Regards,
Bill Boos