[MITgcm-support] seaice_salinity

Dimitris Menemenlis dmenemenlis at gmail.com
Tue Nov 18 12:45:08 EST 2008

Matt, are you sure that it is the sea ice model that is unstable and  
blows up?
Admittedly the CS510 resolution is a little coarser than 1/6 degree  
around Antarctica but we have not had problems with sea ice model  
stability for quite some time.

Also looking back at 1/8 and 1/16 degree integrations, the sea ice was  
stable, although the code has changed since.

I wonder if possibly the aspect ratio of your grid is what causes the  
problem?  For all the integrations mentioned above the grid aspect  
ratio is approximately square.

Do you have any additional information on the specific way in which  
your model blows up?  Do NaNs start creeping in the surface flux  
fields produced by the sea ice model.

What might help would be to diagnose the following:

  249 |SIfu    |  1 |UU      U1      |N/m^2           |SEAICE zonal  
surface wind stress, >0 increases uVel
  250 |SIfv    |  1 |VV      U1      |N/m^2           |SEAICE merid.  
surface wind stress, >0 increases vVel
  251 |SIempmr |  1 |SM      U1      |kg/m^2/s        |SEAICE upward  
freshwater flux, > 0 increases salt
  252 |SIqnet  |  1 |SM      U1      |W/m^2           |SEAICE upward  
heatflux, turb+rad, >0 decreases theta
  253 |SIqsw   |  1 |SM      U1      |W/m^2           |SEAICE upward  
shortwave radiat., >0 decreases theta

in the time step right before and right after the crash.


Dimitris Menemenlis <menemenlis at jpl.nasa.gov>
Jet Propulsion Lab, California Institute of Technology
MS 300-323, 4800 Oak Grove Dr, Pasadena CA 91109-8099, USA
tel: 818-354-1656;  cell: 818-625-6498;  fax: 818-393-6720

On Nov 18, 2008, at 9:23 AM, Matthew Mazloff wrote:

> My biggest concern is how unstable the seaice model is!  Do you know  
> any tricks?  Perhaps turning down max vel. or shortening the time  
> step?

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