[MITgcm-support] Re: MITgcm files

[Renske Gelderloos]

Hi Martin,

Thanks for the advice.  The part about the overlap in SIZE.h  I don't 
really understand though.  Isn't that the amount of grid cells that 
overlap between different tiles? So if you would use only one tile, it 
doesn't make much sense to me to prescribe overlap. Or is it not allowed 
to use only one tile? Furthermore, on my computer the model crashes with 
nonzero overlap.. ("solution is heading out of bounds (...), 
mon_solution: stopping calculation, mon_solution: stopped due to extreme 
values of solution"). So what is the idea behind the tiles and the overlap?

Renske

Martin Losch wrote:
> Hi Renske,
>
> I am returning your files with my modficiations, but all of these are 
> related to general stability of the code. I could not reproduce the 
> problem that you described, namely that a non-zero heat flux does not 
> change the surface temperature. For testing, try a non-uniform heat 
> flux that introduces a horizontal pressure gradient and immediate 
> flow. With a uniform heat flux and uniform initial conditions (in the 
> horizontal) and a stable water column you should never get any flow. 
> (as a side remark: I did get non-zero velocities after the second 
> timestep, which should not happen, but that's not your problem. Is 
> that a problem with step topography, and vertical diffusion? very 
> worrying).
>
> a couple of problems:
> SIZE.h: you set the overlaps to 0, that will probably not work ( and 
> did not work for me, the model blows up immediately, I am surprised 
> that we don't have a catch for that, maybe it is allowed?). I changed 
> them to 4 (but 2 should be enough).
>
> data:
> - deltaT = 86400 is much too large a time step and will also lead to 
> the model blowing up immediately (once there is motion), but you 
> probably knew that
> - I put sref = 15*0.0, (although some compiler will probably take 
> sref=0.0 as well)
> - diffKzT = 20., is awfully large if implicitVerticalDiffusion is not 
> turned on (default). I set it to 1.e-5 for now.
>
> topography:
> - I usually try to set a minimum depth which should be at least the 
> thickness of the top-most grid cell, can be set in "data" by hFacMinDz
>
>
>
>
> On 23 May 2008, at 17:50, Gelderloos, Renske (KNMI) wrote:
>
>> Dear Martin,
>>
>> Here are all the files you requested. I would really appreciate it if 
>> you would want to take a look at it, I'm pretty stuck... Hope you can 
>> help me!
>>
>> Renske
>>
>> ________________________________
>>
>> From: Gelderloos, Renske (KNMI)
>> Sent: Fri 5/23/2008 2:09 PM
>> To: Gelderloos, Renske (KNMI)
>> Subject: MITgcm files
>>
>>
>>
>> <data><data.mnc><data.pkg><eedata><Qnetuniform.bin><topogOBCmatlab.bin><packages.conf><SIZE.h><LabradorOBC.m><heatuniform.m> 
>>
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