[MITgcm-support] Choosing Leith biharmonic co-efficient?

[Malte Jansen]

Just to add on to this: the Leith viscosity is supposed to be "scale 
aware" (at least within a QG turbulence regime), such that the 
non-dimensional coefficient should be independent of the grid-scale.

-Malte


On 4/16/18 3:16 AM, Martin Losch wrote:
> Hi Jody,
>
> my reference is pkg/mom_common/mom_calc_visc.F where you can find this:
>
> C     RECOMMENDED VALUES
> C     viscC2Leith=1-3
> C     viscC2LeithD=1-3
> C     viscC4Leith=1-3
> C     viscC4LeithD=1.5-3
> C     viscC2smag=2.2-4 (Griffies and Hallberg,2000)
> C               0.2-0.9 (Smagorinsky,1993)
> C     viscC4smag=2.2-4 (Griffies and Hallberg,2000)
>
> And I think this is where it is described:
> B. Fox-Kemper and D. Menemenlis. Can large eddy simulation techniques improve mesoscale-rich ocean models? In M. Hecht and H. Hasumi, editors, Ocean Modeling in an Eddying Regime, volume 177, pages 319-338. AGU Geophysical Monograph Series, 2008.
> http://www.geo.brown.edu/research/Fox-Kemper/pubs/pdfs/FoxKemperMenemenlis08.pdf
>
> Martin
>
>> On 14. Apr 2018, at 22:42, Jody Klymak <jklymak at uvic.ca> wrote:
>>
>>
>> Hi all,
>>
>> Is there a good reference and/or ruls of thumb for choosing the Leith biharmonic co-efficient? i.e. `viscC4Leith` and `viscC4Leithd`, with particular interest in how the size of the grid affects the choice?  I’m using someone else’s setup, using Leith works great for making the flow look reasonable, but it would be nice if it was turned down as much as possible, particularly when I downscale to a smaller grid size…
>>
>> Thanks a lot,   Jody
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-- 
Malte F Jansen
Assistant Professor
Department of the Geophysical Sciences
The University of Chicago
5734 South Ellis Avenue
Chicago, IL 60637 USA