[MITgcm-support] GM: Skew flux vs Advective form

[Ryan Abernathey]

Lars,
Unfortunately, I can't really comment on climatological differences between
the skew flux vs adv form.
But I am curious whether using adv form fixed the problems you were having
with the layers diagnostics.
-Ryan


On Thu, Jun 6, 2013 at 2:24 AM, Lars Czeschel <lars.czeschel at zmaw.de> wrote:

> Hi all,
>
> i am running a 1deg global model with version MITgcm_63q. Using the layers
> pkg I noticed
> that my global overturning in density space is divergent (up to 5 Sv in
> ACC latitudes).
> Without bolus velocities or using  ' GM_AdvForm    = .TRUE.,' in
> data.gmredi
> the overturning becomes non-divergent.
>
> As we used the skew flux version frequently in the past (which is also the
> default) I hoped to find
> a bug in the layers pkg but without success. As a further test I ran the
> tutorial example
> 'tutorial_global_oce_latlon'  for 10 years with   GM_AdvForm    = .False.
> compared
> to GM_AdvForm    = .TRUE. in data.gmredi. I attached the quite strong
> differences in theta (z=85m)
> below.
>
> To my understanding the differences should be very small even if the small
> slope assumption
> is made using the skew flux version.
>
> Did I miss something here or do we have an undiscovered bug in the skew
> flux code and
> the advective form should be recommended ?
>
>   Thanks , Lars
>
> p.s: Several years ago Christopher Wolfe reported a related problem
> http://mitgcm.org/pipermail/mitgcm-support/2008-January/005180.html
>
>
> ----------------------------------------------
> Lars Czeschel
> Theoretical Oceanography
> Institut für Meereskunde
> KlimaCampus Universität Hamburg
> Bundesstr. 53
> 20146 Hamburg
>
>
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>
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