[MITgcm-support] Behavior of Ptracers at Orlanski boundary

[Martin Losch]

Hi Yilang,

I think that your only way out is to change the boundary conditions for the passive tracers. You obviously read this old post. Now you know what I mean by “keep your fingers crossed”.

As a quick fix, I usually try to use some approximate v.Neumann BC, but that’s already implemented in the example given in the old post <http://mailman.mitgcm.org/pipermail/mitgcm-support/2012-October/008012.html>

If that doesn’t help you’ll probably have to try to implement Orlanski BC’s for passive tracers …

Martin

> On 11. Apr 2019, at 21:51, Yilang Xu <yxu at whoi.edu> wrote:
> 
> Hi everyone, 
>  
> As MITgcm suggests, the implementation of Orlanski OBCS and Ptracers together is not recommended by the current version of the code. Following some previous discussions
> (e.g., http://mailman.mitgcm.org/pipermail/mitgcm-support/2012-October/008012.html), I comment out the part that stops the model in obcs_calc.F and obcs_check.F. 
>  
> As a result, the model behaves well until the ptracer reaches the Orlanski boundary. I notice the occurrence of instability or aggregation of ptracer when it comes near boundary cells. 
> I wonder if there is any solution to this problem. Appreciate your help. 
>  
> Thanks,
> Yilang
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