[MITgcm-support] Lock exchange problem with the MITgcm

[Jody Klymak]

Hi Flavien,

I'll let the folks who know such things respond to the numerical  
scheme issues, except I'll say I was chastised for using the simpler  
schemes. FWIW I would be surprised to learn that the scheme choice  
greatly changed the grosser scale features of your lock exchange.

On Oct 29, 2009, at  12:03 PM, Flavien Gouillon wrote:

> * *- *The other question is: when running with the 3^rd order upwind  
> advection scheme, my density profile has, in some places, a  
> persistent non-monotic (lighter to denser) feature (unstable  
> conditions, denser water above a lighter one). I thought that  
> running with a hydrostatic model would prevent such thing and will  
> not allow any ‘overturning’ (by quickly mixing any unstable profile)  
> or will blow-up. Is the MITgcm capable of handling such thing even  
> running with the hydrostatic option and without any mixing?*

Absolutely.  The hydrostatic equations are capable of producing an  
overturning bore.  The hydrostatic assumption will mean that you don't  
resolve the details in the bore correctly, but its size and phase  
speed should be approximately correct.

The only counter case I've seen to this is if you are trying to  
resolve solitary waves - they need the non-hydrostatic terms to evolve  
correctly.  Other folks possibly have other cases.

Sonya Legg and I have a paper submitted to Ocean Modelling with a  
(parameter-less!) scheme for estimating the mixing in overturn  
regions; those regions become very important in non-linear generation  
and scattering problems.  It got reasonable first-round of reviews, so  
there shouldn't be any harm in sharing it:

http://web.seos.uvic.ca/~jklymak/pdfs/MixingScheme.pdf

Cheers,  Jody

--
Jody Klymak
http://web.uvic.ca/~jklymak/