[MITgcm-support] RE: Internal wave
Abbas Dorostkar
abbas.dorostkar at ce.queensu.ca
Wed Aug 29 15:37:01 EDT 2007
Hi Jody,
You suggested me to set ends of my box to be depth=0 if I use a close
boundary with a two layer prescribed density profile. I am not sure why
I should do that. Can you give me a clue please.
Thanks,
Abbas
Message: 2
Date: Fri, 17 Aug 2007 10:01:04 -0700
From: Jody Klymak <jklymak at uvic.ca>
Subject: Re: [MITgcm-support] Internal wave
To: mitgcm-support at mitgcm.org
Cc: vtnguyen at uwaterloo.ca
Message-ID: <7AC91C5A-87E0-4674-A6F4-607B600C849F at uvic.ca>
Content-Type: text/plain; charset="windows-1252"
Hi Abbas,
I am hardly a great expert on the MITgcm, but I've used it for
similar cases to what you seem to be after.
On Aug 17, 2007, at 9:20 AM, Abbas Dorostkar wrote:
> I am going to set up the MITgcm for Cayuga Lake, NY. I have run
> internal wave test case but I would like to clarify following
> questions for myself.
> 1) The nonhydrostatic flag is false and model is using semi-
> implicit solver (Am I right?). I am guessing in internal wave on
> slope, nonhydrostatic process could be more important especially in
> small scale (like lab scale)? Have anybody testes this model for
> smaller cases?
Non-hydrostatic should work fine. Just be aware that it will be much
slower. You could try hydrostatic first to get things looking right,
and then move to non-hydrostatic after. You may need to change
deltaT to something smaller as well depending on what mixing scheme
you decide to use.
> 2) I saw a flag "implicitIntGravWave" (default=false) in the list
> of parameters but I could not find any documentation. Can I use it
> in internal wave test case? If yes, Should I use in conjunction
> with nonhydrostatic= 'True'?
I'm not sure about this one, but I do IW simulations with this set to
default of false.
> 3) I wonder how we can define boundary condition on the slope in
> this case. Is it the same as bottom boundary condition?
The slope would be called the bottom if you are asking about
something like where "no_slip_bottom" would be applied. You want the
friction to be along in the vertical direction. BTW, I run this as
FALSE, primarily because I don't have enough resolution to resolve
the bottom boundary layer. If you want there to be bottom drag you
can also specify bottomDragQuadratic=0.003.
> 4) I am not sure which kind of OB is used in this test as it is not
> defined in data.obcs file but by seeing obcs_calc.F , I guess
> Orlanski?
I don't think that example uses Orlanski, or any other radiative
scheme. The obcs_calc.F is making there be a sinusoidal mode-1 wave
in U,V, and temperature on the western boundary. This wave is
allowed to radiate in, onto the shelf. Anything that back radiates
is allowed to bounce around.
> 5) Instead of open boundary forcing, could I use a close boundary
> with a two layer prescribed density profile?
Yes, just set the ends of your box to be depth=0.
> 6) In packages.conf of this test, there is a gfd package. What does
> it do? I could not find this package in pkg folder of MItgcm.
gfd is a short form for a whole bunch of packages. When you run
genmake2 it tells you what they are.
I hope this helps. More complicated questions may be beyond my
expertise!
Cheers, Jody
--
Jody Klymak
http://web.uvic.ca/~jklymak/
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