[MITgcm-support] changing rSphere

[Jonathan Mitchell]

Hi Ed-

I am still getting my mind around the architecture having picked up the 
model just a week or two ago, and I'm still unsure what I should be 
asking when problems arise.  So even though the cubesphere grid is 
mentioned in the introduction of the documentation, I hadn't run across 
it yet.  Thanks for your patience.
I'm using normal spherical polar coordinates; in my "data" namelist, 
"usingSphericalPolarGrid" is set to "true".  I'm trying to set up the 
Held-Suarez benchmark example to run Titan-like conditions; I've 
started with the setup found in "verification/hs94.1x64x5" and changed 
planetary parameters as well as the relaxation temperature profile.  As 
I said previously, I'm able to change the rotation rate, surface 
gravity, surface pressure, etc to mimic Titan, but I wasn't able to set 
the planetary radius below 3500 km (Titan is 2575 km) without the model 
blowing up.
I guess I originally wanted to know if reducing the planetary radius by 
1/2 or more causes problems in general.  I gather this is not the case, 
so I'll have to look more carefully at stability criteria, initial 
conditions, etc. as you suggested.

Best,
Jonathan

On Apr 15, 2005, at 10:24 AM, Ed Hill wrote:

> On Thu, 2005-04-14 at 21:17 -0500, Jonathan Mitchell wrote:
>> Hmm, this is something I haven't learned about yet.  Is there
>> documentation on these "tile*.mitgrid" files?
>
> Hi Jonathan,
>
> In all sincerity, the amount of useful help folks get on this list is
> roughly proportional to the useful info they provide *us*.
>
> So, again, are you using a cubesphere grid?  If so, I'll point you
> towards tools that you can use to scale the grid quantities (that is,
> the pre-computed lengths and areas) with the planetary radius.
>
> And if you're not using a cubesphere grid, then you should look for
> other reasons why the model blows up.  Perhaps one or more of the
> stability criteria scale with the planetary radius?  Or perhaps your
> initial conditions become increasingly unreasonable (violate the CFL
> limit) as you change the radius?
>
> Ed
>
> -- 
> Edward H. Hill III, PhD
> office:  MIT Dept. of EAPS;  Rm 54-1424;  77 Massachusetts Ave.
>              Cambridge, MA 02139-4307
> emails:  eh3 at mit.edu                ed at eh3.com
> URLs:    http://web.mit.edu/eh3/    http://eh3.com/
> phone:   617-253-0098
> fax:     617-253-4464
>
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>
----------------------------------------------
Jonathan Mitchell
Dept. of Astronomy & Astrophysics
University of Chicago
773.834.2160 (w)
773.702.8212 (fax)
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