[MITgcm-support] Negative Passive Tracer Concentration

[Stanislav Martyanov]

Hi Bertrand,

If I'm correct, the default advection scheme in MITgcm is 2nd order
centered one. Instead, try using the DST advection scheme with flux limiter
(code 33). It prevents the occurrence of false extrema,  including
artificial negative concentrations due to advection schemes used. At least,
when I faced a similar problem with ptracer and sea ice, it helped.

Regards,
Stanislav Martyanov

чт, 4 февр. 2021 г. в 02:49, Bertrand Delorme <bdelorme at stanford.edu>:

> Hi everyone,
>
>
>
> I am running an experiment to study mixing driven by internal wave
> breaking. I have incorporated a passive tracer into the experiment as a
> Gaussian patch in the area where the wave is breaking to study the
> evolution of its vertical variance and infer an effective eddy diffusivity
> from that. I have set arbitrarily the passive tracer concentration to be
> between 0 (outside of the Gaussian patch) and 1 (in the center of the
> Gaussian patch).
>
>
>
> Very rapidly in the simulation, I get negative values of the passive
> tracer concentration outside of the Gaussian patch where it is supposed to
> be zero. Is there a way to avoid that? I am using the default advection
> scheme right now.
>
>
>
> Thank you,
>
>
>
> Bertrand
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