[MITgcm-devel] seaice

[Jinlun Zhang]

Martin Losch wrote:

> The story continues:
>
> I ran my configuration with (always with exf and exf_bulkformulae)
> 1. full seaice model
> 2. without seaice model
> 3. with seaice model but unmodified stresses
> 4. with seaice model but with unmodified buoyancy fluxes (store the  
> fluxes at the beginning of seaice_model and restore them at the end  
> of seaice_model)
>    a. all unmodified
>    b. only EmPmR unmodified
>    c. only qnet and qsw unmodified (blows up!!!)
>
> Whenever EmPmR is unmodified the circulation is "bad". That is, the  
> ACC breaks into the Weddell Sea. In particular runs 2, 4a and  4b  
> look reasonable (of course the ice is terrible in a few cases but I  
> don't care about that now), but run 1 and 3 are bad. Unfortunately  
> the run 4c explodes very quickly and I don't know why.
>
> I compared the sfluxtave between run 1 and run 4b (empmr unmodified  
> by ice model). The icemodel adds a freshwater flux to the model that  
> can be 10 to 20 larger than the atmospheric freshwater flux (in the  
> yearly average!!), especially along the boundary of the Weddell Sea.  
> This makes the surface waters along the boundaries much saltier in  
> run1 (with full seaice) than in run 4b (everything but EmPmR  
> modified). As a consquence run4b shows a strong salinity gradient  
> from the coast (fresh) to the center of the Weddell Sea, and a  
> Weddell Gyre develops, whereas in run1 (with full seaice) this  
> gradient is very weak. Comparison with levitus surface salinity does  
> not help, because in the mean there the structure is a different (and  
> I don't know to what extend I can believe that).
>
> Is it reasonable to have yearly average salt fluxes (sflux) on the  
> order of -0.002 to 0.008 (mainly due to the ice model, instead of  
> atmospheric fluxes of -0.002 to 0.0006), divide by s*rhoFresh =  
> (35*1000) to get freshwater fluxes? May there be a problem in the  
> seaice?

Martin, what is the units of these numbers. If the ocean stratification 
is ok with ice in, as you mentioned earlier, then the problem is perhaps 
not freshwater flux, but advection.
Cheers, Jinlun

>
> Martin
>
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