[MITgcm-support] OBCS for sea ice!

liqun_hu818 at yahoo.com.cn liqun_hu818 at yahoo.com.cn
Thu Jun 13 20:22:42 EDT 2013 

Hi, Martin:
      I have tested different solver for the sea ice dynamics, and one questions is that what is  the boundary conditions for the sea ice internal stress calculation under default? I think unrealistic BCs for the calculation of ice stress could be one potential problem for the instability characteristics, which happened in the interior region, but not started from the boundary. When I use the freedrift configuration, it seems that the boundary condition of sea ice has been correctly used, the modeled variables were not perfect, but more resonable.
Best wishes,
Liqun

 



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发送日期： 2013年6月11日, 星期二, 10:08 上午
主题: MITgcm-support Digest, Vol 120, Issue 10
 

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Today's Topics:

   1. OBCS for sea ice! (liqun_hu818 at yahoo.com.cn)


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Message: 1
Date: Tue, 11 Jun 2013 10:08:19 +0800 (CST)
From: liqun_hu818 at yahoo.com.cn
To: "mitgcm-support at mitgcm.org" <mitgcm-support at mitgcm.org>
Subject: [MITgcm-support] OBCS for sea ice!
Message-ID:
    <1370916499.67704.YahooMailNeo at web15906.mail.cnb.yahoo.com>
Content-Type: text/plain; charset="utf-8"

Hi, Martin:
????? Thank you for your reply! I agree with you that the choice of the domain is not a good idea and the setup of the OBCS is really a boring task. 

Best wishes,
liqun

?



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????? 2013?6?11?, ???, 12:00 ??
??: MITgcm-support Digest, Vol 120, Issue 9


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Today's Topics:

?  1. Re: Orlanski boundary conditions (Martin Losch)
?  2. Re: OBCS for sea ice! (Martin Losch)
?  3. Re: Orlanski boundary conditions (Sonya Legg)


----------------------------------------------------------------------

Message: 1
Date: Mon, 10 Jun 2013 09:33:51 +0200
From: Martin Losch <Martin.Losch at awi.de>
To: <mitgcm-support at mitgcm.org>
Subject: Re: [MITgcm-support] Orlanski boundary conditions
Message-ID: <7BD5C675-E2A8-4B74-8F57-2A1713E41306 at awi.de>
Content-Type: text/plain; charset="us-ascii"

Hi Sonya,

I never really had a look at the Orlanski BC, but I don't think that they have changed over time. Here is what I got from grepping the verification directory:
csysm15::verification> grep -i useOrlanski */input*/data.obcs | grep -v "#"
dome/input/data.obcs: useOrlanskiWest=.TRUE.,
dome/input/data.obcs: useOrlanskiNorth=.FALSE.,
obcs_ctrl/input_ad/data.obcs: useOrlanskiNorth=.FALSE.,
tutorial_plume_on_slope/input/data.obcs: useOrlanskiEast=.TRUE.,

So only the forward experiments "dome" (you should be familiar with (o:) and "tutorial_plume_on_slope" both use the Orlanski BC.

Martin

On May 28, 2013, at 5:49 PM, Sonya Legg <sonya.legg at noaa.gov> wrote:

> Dear mitgcm folks,
> 
> I have been using MITgcm_c62q for a long time, running process study simulations of internal waves, forcing the wave at the west boundary with specified boundary conditions, and allowing the wave to propagate out of the domain at the east boundary with orlanski boundary conditions.
> 
> I have a new student starting research with me, and he has been attempting to set the code using the latest version of the code, downloaded last week through CVS. He successfully ran the internal wave test case, but when he added orlanski boundary conditions at the eastern boundary (along with appropriate changes to the data file, i.e. no nonlinear free surface etc), the code blows up. With version c62q he can successfully convert the internal wave test case to run with orlanski boundary conditions at the eastern boundary.
> 
> So my question is: have the orlanski boundary conditions been verified for newer versions of the code? Can you point me to an orlanski boundary condition test case?
> 
> Thanks
> 
> Sonya
> 
> _______________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org
> http://mitgcm.org/mailman/listinfo/mitgcm-support




------------------------------

Message: 2
Date: Mon, 10 Jun 2013 14:53:20 +0200
From: Martin Losch <Martin.Losch at awi.de>
To: <mitgcm-support at mitgcm.org>
Subject: Re: [MITgcm-support] OBCS for sea ice!
Message-ID: <9BA360F9-FE7F-4485-AF16-BC38A7074A7C at awi.de>
Content-Type: text/plain; charset="iso-8859-1"

Hallo Liqun,

to begin with, make sure that SEAICE_maskRHS=.FALSE. (this is the default). I introduced this option mainly for testing purposes, and it should not be used otherwise (and it probably does not work with the open boundary conditions anyway).

In the default case of SEAICE_maskRHS = .FALSE., the corresponding code in seaice_dynsolver.F is not used and seaiceMaskU/V are basically the same as the velocity masks maskW/S(:,:,1,:,:) for the surface ocean velocities. The masks are 2D and apply to the entire domain, and not only to individual boundaries. (and they are only used in the ice dynamics). I assume that your "problem" stems from a different source. 

Also the wrap-around for AREA (and all other variables) is intentional. The boundary conditions are cyclic/periodic by default and only putting a strip of "land" or an open boundary overrides this behavious. 

Judging from your figure (it was difficult to open, to be honest, something like a jpg or png would have been much better), you put your boundaries in the middle of the Arctic, which I would call an unfortunate choice. First of all, open boundary conditions are always problematic, because they are a discontinuity for the dynamics. In particular, you cannot expect too much from the open boundary implementation for seacie, because they were introduced to have a way to remove ice from the domain, e.g. think of a typical pan-Arctic domain, with an open boudary outside the usual ice cover, and the occasionally the ice might reach the boundaries and this case, you want the ice to be able to move out of the domain rather than getting stuck there. Honestly, I am surprised that the solution (at least the plot that you sent) does not appear to have serious issues, except near the boundary, where I would expect them. The noise near the coasts at approximate 125W is
probably a consequence of your setting seaiceMaskU/V=1 everywhere (I would revert to the original code).

For more help on your specific problem you need to give us more information: version/checkpoint of the code, details of the configuration (what do you use in SEAICE_OPTIONS.h, OBCS_OPTIONS.h, data.obcs, data.seaice, etc). The problem description is also a little unclear.

Martin


On Jun 8, 2013, at 8:06 AM, <liqun_hu818 at yahoo.com.cn> wrote:

> Hi, all:
>? ?  I am now trying setup a regional ice-ocean coupled application with MITgcm checkpoint64h, OBCs are prescribed from global model products. 
>? ?  However, there is some problem with the Vvel at the southern boundary and the Uvel at the western boundary. These two boundary value are masked by the northern and eastern sea ice velocity mask. I checked the obcs_apply_uvice.F, and commented the seaiceMaskU/V, the problem still exist. And so I changed the value of seaiceMaskU/V to 1 in the seaice_init_varia.F, this kind problem could be solved.
>? ?  After checking the code, I found that seaiceMaskU(i,Jsouth)=AREA(i,Jsouth)+AREA(i,Jsouth-1), and if Jsouth=1, it seems that the AREA(i,0) is set to be AREA(I,end), simila with the western boundary with Iwest=1. 
>? ?  Though the seaiceMaskU/V are mainly used in the dynamic solver, could there be other problems?
> Best wishes,
> liqun
>? 
> 
> 
> _______________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org
> http://mitgcm.org/mailman/listinfo/mitgcm-support




------------------------------

Message: 3
Date: Mon, 10 Jun 2013 09:14:50 -0400
From: Sonya Legg <sonya.legg at noaa.gov>
To: mitgcm-support at mitgcm.org
Subject: Re: [MITgcm-support] Orlanski boundary conditions
Message-ID: <51B5D14A.40208 at noaa.gov>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Hi martin,

Thanks, I'll try the dome test case. But the internal waves one 
definitely breaks when we turn on the orlanski bcs, although with c62 it 
works fine.

Sonya

On 6/10/2013 3:33 AM, Martin Losch wrote:
> Hi Sonya,
>
> I never really had a look at the Orlanski BC, but I don't think that they have changed over time. Here is what I got from grepping the verification directory:
> csysm15::verification> grep -i useOrlanski */input*/data.obcs | grep -v "#"
> dome/input/data.obcs: useOrlanskiWest=.TRUE.,
> dome/input/data.obcs: useOrlanskiNorth=.FALSE.,
> obcs_ctrl/input_ad/data.obcs: useOrlanskiNorth=.FALSE.,
> tutorial_plume_on_slope/input/data.obcs: useOrlanskiEast=.TRUE.,
>
> So only the forward experiments "dome" (you should be familiar with (o:) and "tutorial_plume_on_slope" both use the Orlanski BC.
>
> Martin
>
> On May 28, 2013, at 5:49 PM, Sonya Legg <sonya.legg at noaa.gov> wrote:
>
>> Dear mitgcm folks,
>>
>> I have been using MITgcm_c62q for a long time, running process study simulations of internal waves, forcing the wave at the west boundary with specified boundary conditions, and allowing the wave to propagate out of the domain at the east boundary with orlanski boundary conditions.
>>
>> I have a new student starting research with me, and he has been attempting to set the code using the latest version of the code, downloaded last week through CVS. He successfully ran the internal wave test case, but when he added orlanski boundary conditions at the eastern boundary (along with appropriate changes to the data file, i.e. no nonlinear free surface etc), the code blows up. With version c62q he can successfully convert the internal wave test case to run with orlanski boundary conditions at the eastern boundary.
>>
>> So my question is: have the orlanski boundary conditions been verified for newer versions of the code? Can you point me to an orlanski boundary condition test case?
>>
>> Thanks
>>
>> Sonya
>>
>> _______________________________________________
>> MITgcm-support mailing list
>> MITgcm-support at mitgcm.org
>> http://mitgcm.org/mailman/listinfo/mitgcm-support
>
> _______________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org
> http://mitgcm.org/mailman/listinfo/mitgcm-support




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