[MITgcm-support] is Orlanski radiation condition working in the rotating rank of MITgcm?

[Yi-Chih Huang]

Martin,

    Thanks much for the reply.  I conduct idealized simulations around the
Arctic regions.  Thus, I need to work on curvilinear coordinates to resolve
the singularity problem.  I started with the grids on arctic40km and
cs_4km.  Generally, I got the numerical disturbances around the lateral
boundary as the .png file.  I tried to update thelateral boundary condition
with Orlanski b.c. by adding obcs in packages.conf and useOBCS=.TRUE.,
in data.pkg, along with the data.obcs file.  Hopefully the attached file in
code, data.pkg, data.obcs, and data are clear enough.  The input
files include rhoRefFile, bathyFile, and hydrogThetaFile.  The
hydrogThetaFile is three dimensional so I don't want to attach it.
Probably my update in b.c. was not successful because the temperature
patterns are the same as the original one.  Thus, I did not attach another
.png file.  I wonder how to update with the Orlanski b.c. in MITgcm?

    I will study a planet other than the Earth.  Hence, the grids of arctic40km
and cs_4km will not be suitable for this work.  I wonder the relations
between radius and grids information on the curvilinear coordinates and
what to start with?


    Hopefully, my descriptions are clear enough and thanks much for your
help,


               Yi-Chih


Date: Mon, 17 Dec 2018 10:49:50 +0100
From: Martin Losch <Martin.Losch at awi.de>
To: MITgcm Support <mitgcm-support at mitgcm.org>
Subject: Re: [MITgcm-support] is Orlanski radiation condition working
        in the rotating rank of MITgcm?
Message-ID: <30F990A0-C8E6-45D5-8C24-13EDF0112321 at awi.de>
Content-Type: text/plain; charset="utf-8"

Yi-Chih,

I am sorry. I don?t understand what you are doing (and why, but that?s
maybe not so important).

Does you config have anything to do with verification/rotating_tank?
This experiment mimics a small tank on a turntable in a lab. It?s not clear
to me how to upscale that to the Arctic without fundamentally changing the
parameters of the model.
Thus, I cannot follow your conclusions that you can fix anything with open
boundaries. You need to make sure that your flow parameters are set
correctly (eg. horizonal and vertical viscosity, Coriolis parameter, etc ?.)

Using the grid data from arctic40km or cs_4km confuses me even more in this
context. If you do things like this, the coriolis parameter should be
automatically set according to the latitudes in the domain. You cannot
change the radius of the earth without adjusting the grid information
(because grid spacing ~ radius of the earth).

I don?t think anyone can help you with this unless you are clearer about
you configuration. Maybe it would be a good idea to
(1) post your configuration somewhere, namelist files, ?code? directory,
?input files" (please no large files on this list)
(2) post a plot of the ?disturbances? that you observe, with and without
orlanski obcs

Martin

>
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