[MITgcm-support] EVP subcycling

[Naughten, Kaitlin A.]

Hi Martin,


Sorry for my slow reply - I wanted to confirm that my solution was indeed stable before I responded! Thanks to your suggestions I found the right mEVP parameters (my configuration seems to be more stable with mEVP than with aEVP or LSR, at least for the parameters I tried) and the blowup I was struggling with for weeks hasn't shown itself since. I think it was just a case of not enough subcycles. Thanks again for all your help during this setup stage.


All the best,

Kaitlin

________________________________
From: MITgcm-support <mitgcm-support-bounces at mitgcm.org> on behalf of Martin Losch <Martin.Losch at awi.de>
Sent: 15 June 2018 13:43:22
To: MITgcm Support
Subject: Re: [MITgcm-support] EVP subcycling

Hi Kaitlin,

I do not recommend using EVP at all, unless you want to use the “modified” EVP, mEVP or aEVP. I think that the documentation (<https://mitgcm.readthedocs.io/en/latest/phys_pkgs/seaice.html>) should give you an idea how to use either variant. With mEVP or aEVP you may get away with as few as 50 to 100 iterations, but you need check your output fields.

If you decide against EVP altogether, I recommend using at least 10 OL iterations (SEAICEnonlinIterMax) and a higher accuracy of the linear solver (LSR_ERROR = 1e-5 or smaller).

Martin

> On 15. Jun 2018, at 12:50, Naughten, Kaitlin A. <kaight at bas.ac.uk> wrote:
>
> Hello,
>
> Is there a rule of thumb for choosing how many subcycles EVP does (i.e. SEAICE_deltaTevp versus deltaT)? Does anyone here follow a specific procedure to decide on the best ratio?
>
> Many thanks,
> Kaitlin
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