[MITgcm-support] Re: single layer run

[Sergey Vinogradov]

Martin:
I do initialize the experiment with prescribed SSH (which is computed as 
inverted barometer for the initial atm.pressure). Then the atm. pressure 
forcing evolves in time and space. I don't have problems with several 
layers configuration, but in a single-layer setup the model doesn't seem 
to "feel" the atm. pressure forcing at all, instead, it just solves the 
problem of the barotropic adjustment of the initial condition. I was 
thinking if the single layer is really applicable for this type of 
experiment?
Regards
Sergey

Martin Losch wrote:

> Sergey,
>
> if you apply pressure forcing that evolves in time, then your flow 
> field should also vary in time. Even if your pressure forcing is 
> constant in time (and variable in space), you should reach a 
> non-trivial steady state (inverted barometer effect), that should have 
> something like the following balance:
> f*v + g*d(ssh)/dx + (1/rho0)*dp/dx = 0 (and something similar for the 
> v-momentum equation, with p=atmospheric pressure), note that the ssh 
> can (and probably will) be zero in this case.
> There is  a verification experiment that does this with 4 layers 
> (inverted_barometer) and constant (in time) forcing. Maybe you can 
> modify this experiment, or try to see what's different in your case?
>
> What do you mean by initial sea-surface height? Do you prescribe an 
> initial SSH?
>
> Martin
>
> On May 10, 2005, at 10:47 PM, Sergey Vinogradov wrote:
>
>> Hi Ed:
>> The pressure loading is a realistic variable forcing.
>> Actually this raises the question if a single layer is a valid 
>> configuration for such experiment...
>> Regards
>> Sergey
>>
>> Ed Hill wrote:
>>
>>> Hi Sergey,
>>>
>>> I've subscribed you to the MITgcm-support email list so that any
>>> subsequent emails you send will get through.  And I've forwarded your
>>> email below.
>>>
>>> In regards to your question, wouldn't one expect the ocean to reach a
>>> quiescent (zero-velocity) solution if it were forced with a steady
>>> atmospheric pressure?  Or are you varying the atmospheric pressure over
>>> time and space?
>>>
>>> Ed
>>>
>>> === original message ===
>>>
>>> Hello,
>>>
>>> After enough playing with a global baroclinic runs, I decided to try a
>>> barotropic run for which I set eosType to 'linear' and specify a single
>>> layer with delZ=5000. After several timesteps, the initial sea-surface
>>> height in the open ocean just dies to zero, while the initial ssh along
>>> the coasts stays the same. No other terms have been changed from the
>>> baroclinic experiment setup. Any suggestions how to make it run will be
>>> greatly appreciated. I forgot to mention that I force the model with
>>> atmosperic pressure only.
>>>
>>> Regards,
>>> Sergey Vinogradov
>>>
>>>
>>>
>>
>> _______________________________________________
>> MITgcm-support mailing list
>> MITgcm-support at mitgcm.org
>> http://mitgcm.org/mailman/listinfo/mitgcm-support
>>
> Martin Losch // Alfred-Wegener-Institut für Polar- und Meeresforschung
> Postfach 120161, 27515 Bremerhaven, Germany
> mailto:mlosch at awi-bremerhaven.de // Tel./Fax: ++49(471)4831-1872/1797
> http://www.awi-bremerhaven.de/People/show?mlosch
>
>
> _______________________________________________
> MITgcm-support mailing list
> MITgcm-support at mitgcm.org
> http://mitgcm.org/mailman/listinfo/mitgcm-support