[MITgcm-support] C-D scheme etc.

[Martin Losch]

Hi D.W.,

1) although I am not a C-D-scheme specialist, here's my experience: The 
overall effect of this scheme that the horizontal velocity field is 
smoother than without it. As long as you can resolve the deformation 
radius, you probably should avoid the C-D-scheme. You may want to avoid 
it altogether and increase horizontal viscosity instead, although 
that's not the same (see Adcroft etal 1999 MWR, pp1928).

2) and 3) It is my personal loss that I have not yet looked at the 
diagnostics package, but I believe it provides the infrastructure for 
what you want to do.

As far as PP81 goes, the package is not documented (as you may have 
seen), the reason being that I haven't yet fully  tested the 
implementation (the same goes for MY82, GGL90). I would be very happy 
about feedback about this package.

Martin

On Oct 26, 2005, at 7:03 AM, David Wang wrote:

> Hello folks,
>
> I have a couple of issues to make sure in the case you may help to 
> clarify.
> ****
> 1). It is said in the manual, to run the model at a sufficiently 
> coarse/*//*/ resolution, one will need the C-D scheme for the 
> computation of the Coriolis terms. And the parameter tauCD (C-D scheme 
> coupling timescale in second) needs to be set. my question is: how 
> coarse is "sufficiently coarse? what about 1-by-1 degree? 1-by-0.3 
> degree? Does it have any side-effect? is it sensitive to tauCD?
>
> 2). I’m wondering if there is any simple way, without writing out the 
> entire three-dimensional variable fields, to monitor the evolution of 
> such time series as the NINO3 index, the EUC transport at a particular 
> longitude etc.
>
> 3). I checked out available_diagnostics.log and didn’t find 
> diagnostics for PP81 vertical viscosity/diffusivity (KPP does have 
> though). I know they can be computed externally using uvel, vvel, 
> \theta, \alpha \nu0 etc., but is there any alternative means to make 
> them available?
>
> Thanks a lot,
> - D.W.**
>
> -- 
> Daiwei (David) Wang    Graduate Student
> Lamont-Doherty Earth Observatory of Columbia University
> 103B Oceanography
> 61 Route 9W, Palisades, NY 10964-8000
> Voice: (845) 365-8694
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