[MITgcm-support] Ricr and MLDs

[David Ullman]

Hello all,
I'm working with Galen McKinley and Stephanie Dutkiewicz to fine tune  
our 0.5X0.5 North Atlantic setup.  Initially we were getting mixed- 
layer depths that were too deep in comparison to the WOA01 data.  It  
was suggested that we reduce our Richardson number cutoff (Ricr) in  
the KPP scheme to shallow the MLDs.

 From the MITgcm website and my own searches through the code, it  
seem as though the only place to make this change is under the  
kpp_readparms.F script.  I reduced the Ricr to .27 and .24 (by  
altering the file under my /na_test/code folder so as not to change  
the original code), recompiling after each reduction to get two  
executables with reduced Ricr.

I then used a pickup file from a 66-year spin-up that used the  
original Ricr of .30.  I ran the new Ricr runs for 5 years each from  
this pickup.  At the end of these runs, I compared the MLDs.  I found  
that there was no difference in MLDs between Ricr=.3, .27, or .24.   
This seems a bit strange.

Am I missing something in my setup?  Is there perhaps some other  
place in the code where I should adjust the Ricr?

Thanks for your help,

David Ullman

Graduate Student
Atmospheric and Oceanic Sciences
University of Wisconsin Madison
ullman at wisc.edu