[MITgcm-support] Re: MITgcm-support Digest, Vol 74, Issue 10

[Marcello Gatimu Magaldi]

Hello to everybody.

I am an MITgcm newbie but I have some experience with other ocean models
(ROMS, HYCOM, POM). I have some specific questions about the (in)famous
OBCS package.

I went through the code. Please correct me if I am wrong (very likely) 
but it
seems to me that:
1) obcs for the ssh are only defined if NONLIN_FRSURF is defined
2) even if NONLIN_FRSURF is defined OBEeta and similars are:
    a) put to zero if neither orlanski nor obcs_prescribe are defined
    b) not even assigned to a value if orlanski or obcs_prescribe are 
defined

Now I was wondering if this is done on purpose. Don't we always need 
boundary
conditions for eta? I am confused since the MITgcm remains different from
the models cited above because it always solves an elliptic equation for
ssh. The other models employ the time-splitting technique and they always
are in need of obcs for ssh and for BAROTROPIC vertically-averaged 
velocities.
In these cases, ob conditions reflecting the hyperbolicity of the equations
solved such as characteristic method or flather conditions can be employed.
Cannot we do the same for MITgcm?
Thanks,
m.

-- 
Marcello Gatimu Magaldi, Ph.D.
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The Johns Hopkins University
Department of Earth and Planetary Sciences
328 Olin Hall
34th and North Charles Streets
Baltimore, Maryland 21218, USA
e-mail: < Marcello.Magaldi at jhu.edu >
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