[MITgcm-devel] changes to very sensitive evp code

[Jean-Michel Campin]

Hi Martin,

In my opinion, you can make these changes and update the output
(with some doc to explain what did change when you check-in the 
new output).
And I can update the adjoint output once the forward one is checked-in.

Cheers,
Jean-Michel

On Fri, Jan 04, 2013 at 10:36:02AM +0100, Martin Losch wrote:
> Hi Jean-Michel and others,
> 
> for completeness, I'd like to implement the modified EVP* of Lemieux et al (2012). In order to be able to use the present (then old) EVP implementation, I have to introduce a few factors, etc. As you know, EVP is very sensitive to everything, so changing
> SEAICEmassU/SEAICE_deltaTevp
> to 
> recip_deltaT = 1. _d 0 / SEAICE_deltaTevp
> SEAICEmassU*recip_deltaT
> already breaks the forward testreport for lab_sea.hb87 (only 2 digits of agreement left for the cg2d solver). Anything else that I do, does the same, eg. replacing
> denom1 = 1./(1.+0.5*dt/tau)
> with 
> alph = 2*tau/dt
> denom1 = alph/(alph+1)
> has the same effect (in fact the difference between the two expressions is not zero but 1.110223e-16 on my linux computer)
> 
> Should I go ahead anyway and update the reference output? Can I ask you to update the adjoint, once I am done? EVP is not tested anywhere else.
> 
> Martin
> 
> 
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