[MITgcm-support] Top boundary conditions

Sat Feb 6 12:25:39 EST 2010

Hi Georgy,
what do you need this for? In "realistic" cases, oceanic surface friction (at the air-sea interface) is realized by imposing wind stress. If you want an ocean with a solid lid on it, you could try (and "abuse") the ice-shelf package (pkg/shelfice, see verificationi/isomip for an example application) and put thin ice-shelp on top of your ocean. Then you can add friction a the ice-ocean interface (have a look at the possible parameters in shelfice_readparms.F)

Martin

On Feb 5, 2010, at 11:37 PM, Georgy Manucharyan wrote:

> Hello,
> For the ocean gcm, is there a way to impose friction at the surface (no slip b.c.)?
> Thanks for your help,
> Georgy.
> 
> 
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>> Today's Topics:
>> 
>>   1. Re: bottom pressure diagnostics (Jean-Michel Campin)
>>   2. Re: bottom pressure diagnostics (Oliver Jahn)
>>   3. Re: bottom pressure diagnostics (Oliver Jahn)
>> 
>> 
>> ----------------------------------------------------------------------
>> 
>> Message: 1
>> Date: Fri, 5 Feb 2010 05:22:12 -0500
>> From: Jean-Michel Campin <jmc at ocean.mit.edu>
>> To: mitgcm-support at mitgcm.org
>> Subject: Re: [MITgcm-support] bottom pressure diagnostics
>> Message-ID: <20100205102212.GA28909 at ocean.mit.edu>
>> Content-Type: text/plain; charset=us-ascii
>> 
>> Hi Dimitris,
>> 
>> I would assume the same thing as you.
>> I will check when I am back from vacation.
>> Cheers,
>> Jean-Michel
>> 
>> On Thu, Feb 04, 2010 at 08:33:07AM -0800, Dimitris Menemenlis wrote:
>>  
>>> Jean-Michel, I will be very interested to hear your answer too.
>>> 
>>> Martin, up to now, I have always assumed that PHIBOT is the bottom pressure,
>>> specifically that PHIBOT in m^2/s^2 is the anomaly relative to Depth * rhonil * g
>>> so that the absolute bottom pressure in Pa is:
>>> Depth * rhonil * g + PHIBOT * rhonil
>>> 
>>> 6-hourly output of ETAN and PHIBOT is available for cube78 and cub81
>>> is available online and on skylla.
>>> 
>>> Dimitris
>>> 
>>> On Feb 4, 2010, at 8:00 AM, Martin Losch wrote:
>>> 
>>>    
>>>> Hi Jean-Michel (and Dimitris),
>>>> 
>>>> we would like to cube78 or cube81 bottom pressure results. Can you confirm that for a time series of anomalies (in time) we need both PHIBOT and ETAN (for the linear free surface contribution):
>>>> 
>>>> bottom pressure = gravity*rhoConst*ETAN + PHIBOT/rhoConst (+terms that are constant in time)
>>>> 
>>>> From looking at calc_phi_hyd I gather, that the non-linear free surface contribution etaH is only included, when selectRstar=0, which is not the case in cube78/81, correct? But in diags_phi_rlow, it says in the head that phi_hyd_rlow is actually bottom pressure. I am confused.
>>>> 
>>>> Martin
>>>> 
>>>> 
>>>> _______________________________________________
>>>> MITgcm-support mailing list
>>>> MITgcm-support at mitgcm.org
>>>> http://mitgcm.org/mailman/listinfo/mitgcm-support
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>> 
>> 
>> 
>> ------------------------------
>> 
>> Message: 2
>> Date: Fri, 05 Feb 2010 09:43:23 -0500
>> From: Oliver Jahn <jahn at mit.edu>
>> To: mitgcm-support at mitgcm.org
>> Subject: Re: [MITgcm-support] bottom pressure diagnostics
>> Message-ID: <4B6C2E8B.3080000 at mit.edu>
>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>> 
>> Hi,
>> 
>> as far as I can tell, the surface contribution is added at the end of diags_phi_rlow.F.  HOWEVER, prior to cvs 2010-01-15, the vertical integral did not take the stretching of the column with nonlinFreeSurf=4 into account, i.e., the diagnostic computed
>> 
>>   PHIBOT = gravity*ETAN + Depth/(Depth+ETAN) * gravity * \int (rho/rhoConst) dr
>> 
>> rather than
>> 
>>   PHIBOT = gravity*ETAN + gravity * \int (rho/rhoConst) dr
>> 
>> You may want to correct for this.
>> 
>> Oliver
>> 
>> 
>> On 2010-02-05 05:22, Jean-Michel Campin wrote:
>>  
>>> Hi Dimitris,
>>> 
>>> I would assume the same thing as you.
>>> I will check when I am back from vacation.
>>> Cheers,
>>> Jean-Michel
>>> 
>>> On Thu, Feb 04, 2010 at 08:33:07AM -0800, Dimitris Menemenlis wrote:
>>>    
>>>> Jean-Michel, I will be very interested to hear your answer too.
>>>> 
>>>> Martin, up to now, I have always assumed that PHIBOT is the bottom pressure,
>>>> specifically that PHIBOT in m^2/s^2 is the anomaly relative to Depth * rhonil * g
>>>> so that the absolute bottom pressure in Pa is:
>>>> Depth * rhonil * g + PHIBOT * rhonil
>>>> 
>>>> 6-hourly output of ETAN and PHIBOT is available for cube78 and cub81
>>>> is available online and on skylla.
>>>> 
>>>> Dimitris
>>>> 
>>>> On Feb 4, 2010, at 8:00 AM, Martin Losch wrote:
>>>> 
>>>>      
>>>>> Hi Jean-Michel (and Dimitris),
>>>>> 
>>>>> we would like to cube78 or cube81 bottom pressure results. Can you confirm that for a time series of anomalies (in time) we need both PHIBOT and ETAN (for the linear free surface contribution):
>>>>> 
>>>>> bottom pressure = gravity*rhoConst*ETAN + PHIBOT/rhoConst (+terms that are constant in time)
>>>>> 
>>>>> From looking at calc_phi_hyd I gather, that the non-linear free surface contribution etaH is only included, when selectRstar=0, which is not the case in cube78/81, correct? But in diags_phi_rlow, it says in the head that phi_hyd_rlow is actually bottom pressure. I am confused.
>>>>> 
>>>>> Martin
>>>>> 
>>>>> 
>>>>> _______________________________________________
>>>>> 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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>>> MITgcm-support mailing list
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>>> http://mitgcm.org/mailman/listinfo/mitgcm-support
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>> 
>> 
>> 
>> ------------------------------
>> 
>> Message: 3
>> Date: Fri, 05 Feb 2010 10:03:23 -0500
>> From: Oliver Jahn <jahn at mit.edu>
>> To: mitgcm-support at mitgcm.org
>> Subject: Re: [MITgcm-support] bottom pressure diagnostics
>> Message-ID: <4B6C333B.4060409 at mit.edu>
>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>> 
>> Sorry, it is the anomaly relative to Depth*rhoConst, of course,
>> 
>> cvs prior to 2010-1-15:
>> 
>> PHIBOT = gravity*ETAN + Depth/(Depth+ETAN) * gravity * \int (rho/rhoConst - 1) dr
>> 
>> should be:
>> 
>> PHIBOT = gravity*ETAN + gravity * \int (rho/rhoConst - 1) dr
>> 
>> Oliver
>> 
>> 
>> On 2010-02-05 09:43, Oliver Jahn wrote:
>>  
>>> Hi,
>>> 
>>> as far as I can tell, the surface contribution is added at the end of
>>> diags_phi_rlow.F. HOWEVER, prior to cvs 2010-01-15, the vertical
>>> integral did not take the stretching of the column with nonlinFreeSurf=4
>>> into account, i.e., the diagnostic computed
>>> 
>>> PHIBOT = gravity*ETAN + Depth/(Depth+ETAN) * gravity * \int
>>> (rho/rhoConst) dr
>>> 
>>> rather than
>>> 
>>> PHIBOT = gravity*ETAN + gravity * \int (rho/rhoConst) dr
>>> 
>>> You may want to correct for this.
>>> 
>>> Oliver
>>> 
>>> 
>>> On 2010-02-05 05:22, Jean-Michel Campin wrote:
>>>    
>>>> Hi Dimitris,
>>>> 
>>>> I would assume the same thing as you.
>>>> I will check when I am back from vacation.
>>>> Cheers,
>>>> Jean-Michel
>>>> 
>>>> On Thu, Feb 04, 2010 at 08:33:07AM -0800, Dimitris Menemenlis wrote:
>>>>      
>>>>> Jean-Michel, I will be very interested to hear your answer too.
>>>>> 
>>>>> Martin, up to now, I have always assumed that PHIBOT is the bottom
>>>>> pressure,
>>>>> specifically that PHIBOT in m^2/s^2 is the anomaly relative to Depth
>>>>> * rhonil * g
>>>>> so that the absolute bottom pressure in Pa is:
>>>>> Depth * rhonil * g + PHIBOT * rhonil
>>>>> 
>>>>> 6-hourly output of ETAN and PHIBOT is available for cube78 and cub81
>>>>> is available online and on skylla.
>>>>> 
>>>>> Dimitris
>>>>> 
>>>>> On Feb 4, 2010, at 8:00 AM, Martin Losch wrote:
>>>>> 
>>>>>        
>>>>>> Hi Jean-Michel (and Dimitris),
>>>>>> 
>>>>>> we would like to cube78 or cube81 bottom pressure results. Can you
>>>>>> confirm that for a time series of anomalies (in time) we need both
>>>>>> PHIBOT and ETAN (for the linear free surface contribution):
>>>>>> 
>>>>>> bottom pressure = gravity*rhoConst*ETAN + PHIBOT/rhoConst (+terms
>>>>>> that are constant in time)
>>>>>> 
>>>>>> From looking at calc_phi_hyd I gather, that the non-linear free
>>>>>> surface contribution etaH is only included, when selectRstar=0,
>>>>>> which is not the case in cube78/81, correct? But in diags_phi_rlow,
>>>>>> it says in the head that phi_hyd_rlow is actually bottom pressure. I
>>>>>> am confused.
>>>>>> 
>>>>>> Martin
>>>>>> 
>>>>>> 
>>>>>> _______________________________________________
>>>>>> 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
>>>>>        
>>>> _______________________________________________
>>>> MITgcm-support mailing list
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>>>> http://mitgcm.org/mailman/listinfo/mitgcm-support
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>>> http://mitgcm.org/mailman/listinfo/mitgcm-support
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>> 
>> 
>> 
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>> End of MITgcm-support Digest, Vol 80, Issue 3
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