[MITgcm-devel] Re: overturning on cubed sphere

[Jean-Michel Campin]

Hi Martin,

On Mon, Sep 19, 2005 at 12:00:01PM +0200, Martin Losch wrote:
> Hi Jean-Michel,
> 
> this is an off-list email, because I don't want to complain publically 
> (o:
> 

I will not cc to the support list, but at least to mitgcm-devel, 
since others might be interested.

> I have been playing around with the cubed sphere configuration 
> (global_ocean.cs32x15), tried to plot a few things, etc. and ran into a 
> few problems with the scripts, that can be found in utils/cs_grid. From 
> the programming style I gather, that they are all yours.
> How reliable is the overturning calculation? I tried your script on the 
> testreport output (the 20 timesteps), and found the results really 
> strange (no real overturning cell etc., see attachment ot.eps). When I 
> tried to use w instead of v (integral south to north of zonal mean of 
> w, quick and dirty interpolation of w onto a regular lat-lon-grid), I 
> get a funny result near the equator (which I sort of expected), but 
> otherwise it looks quite good and familiar, so the fields seem to be 
> OK. I know all this broken line stuff is quite complicated and you have 
> spent a lot of time on this but I can't get it to plot a reasonable 
> overturning streamfunction. Do you?

I tried to use "use_bk_line.m" (now in utils/matlab/cs_grid/) after running 
the global_ocean.cs32x15 for 20 time-steps, with taveFreq=864000., just to 
get some output fields (hUtave & hVtave). 
And I don't get the same plot as you. Mine does not look great, because a 
10 days average is certainly not enough to filter the seasonal cycle, but 
I get an NADW cell (> 10 Sv) as far north as 60-65.N. It would be much 
better to run it for (at least) 1 year and to re-do the plot with annual-mean
fields. But anyway, something is strange in your plot.
I propose:
either that you check again that you are doing the right things.
or 
to tell exactly what you are going, so that we can check.

> 
> I have now my own version of a 2D plot of cubed sphere fields. It's a 
> little less sophisticated than your grphCS.m, but more flexible, and 
> uses only minimal input arguments. Are you interested (see attachment)?
> 
> Martin

We were in the process of gathering (cleaning ? not yet) and documenting 
the matlab scripts, and specially the CS-grid ones. We already have few
versions of merccube.m , few grph_CS.m that are arround, we can 
add an other one. But at some point, it would be nice to review what
each of them does that the others don't, and to merge them into a single
one that has all in it. Would you be interested in telling what
your script do better that the others ?

Thanks,

Jean-Michel