[MITgcm-support] cd_code and oceanic packages

[Ed Hill]

On Fri, 2006-08-18 at 18:15 -0400, Nicolas Wienders wrote:
> What are the cd_code and oceanic packages for?
> Thanks. Have a good week-end.

Hi Nicolas,

Alistair wrote the cd_code package so he is probably the best person to
ask if you want an authoritative explanation.  As it was explained to
me, the cd_code package implements a "C-D scheme" (where U,V velocities
are alternated on C-grid and D-grid staggerings) that is meant to fix a
computational mode which is sometimes excited when the Coriolis force is
exactly aligned with a relatively low-resolution lat-lon grid.  The
problem supposedly does not occur for other relatively low-res grids
that are not exactly aligned with the Coriolis acceleration (eg.
cube--sphere grids, rotated lat-lon grids, or other general curvilinear
grids).  I've heard that the "C-D scheme" works by making the system
more viscous (dissipative) which squashes the high-frequency noise.

The "oceanic" one is not a package per se -- it is a named group of
other packages as defined in the file:  MITgcm/pkg/pkg_groups

Ed

-- 
Edward H. Hill III, PhD
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