[MITgcm-support] cell size variation

[Martin Losch]

the rule of thumb is:
abs(delz(k+1)/delz(k)) < 1.4
In your case: 0.03/0.005 = 6

Martin

On 9 Apr 2008, at 10:34, Patrick Rosendahl wrote:
> Hello all,
>
> I get unstable results with the following configuration in free- 
> surface and non-hydrostatic mode:
>
> delZ=1*0.03,100*0.005,
>
> The depth is 0.5m, divided into a 3cm upper layer (that will  
> contain the free surface), and the rest is divided into 5mm layers.
>
>
> In the mail "Re: [MITgcm-support] z coordinate" from Baylor Fox- 
> Kemper:
> >Hi Rima,
> >  The MITgcm is not accurate when you change the delZ so rapidly.   
> You
> >are much better off using the 20 levels, if you can afford to run it
> >that way.  If not, you can make a few levels of delz=30m, then
> >gradually increase until you reach bottom.  The grid size shouldn't
> >increase too rapidly from level to level, approximately 20% at most.
> >This will be even more important in nonhydrostatic mode.
> >   -Baylor
>
>
> Is there a guide for the cell thickness? Is 20% really necessary?
>
> Best,
> Patrick
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