[MITgcm-support] Abnormal high and low temperature in model

[Jean-Michel Campin]

Hi Yinghui,

It's most likely due to over-shoot / under-shoot of the 
default (Centered 2nd order) advection scheme.
you can try instead a (quasi) monotonous advection scheme
(tempAdvScheme=77, or tempAdvScheme=33 ) and see if it fixes
or at least improves things.
(When you run this test, probably better to use the same advection 
scheme for temp & salt, and to turn on staggerTimeStep=.TRUE.,)

And if you want to keep the same advection scheme (Centered 2nd order),
would need to increase the explicit horizontal (and may be also vertical ?)
diffusion.

Cheers,
Jean-Michel

On Fri, Jul 09, 2010 at 01:11:05AM +0800, 何映晖 wrote:
> Hi,
> 
> 
> I’m running a global ocean model with variable grid-space. Yearly mean *
> Trenberth* wind stress is used to drive the ocean circulation. And surface
> temperature and salinity restoring boundary conditions are set.
> 
> Though the model does not blow up after several years’ runs, some points
> with abnormal high or low temperature are found from the model, whereas
> there are no points of abnormal velocity near those abnormal temperature
> points. And I find those abnormal temperature points mainly emerge at the
> bottom layer. So I wonder why this problem occurred. Does the problem stem
> from bottom friction? Or because of the wrong value of mixing parameter set?
> How can I deal with these problems?
> 
> The "data" file is in attachment. And some figures of these abnormal points
> at Japan Sea are also attached. Figure 1
> 
> Fig. 1 illuminates temperatures at 22th layers, middle depth of 2840 meters.
> max temperature is up to 49.08℃, and minimum of -13.37℃. Fig. 2 shows the
> abnormal maximum salinity of 57.67 ppt corresponding to the abnormal point
> of max temperature. Fig. 3 shows the velocity at the same layer.
> 
> Any suggestion to me will be deeply appreciated.
> 
> 
> 
> Best regards,
> 
> Yinghui He
> 
> 
> -- 
> Yinghui He
> South China Sea Institute of Oceanology
> Chinese Academy of Sciences





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