[MITgcm-support] High diffusion offline runs blow up

[Emma Boland]

Hi all,

I'm running 2D offline runs of MITgcm 62m at 1/20 degree, using 
advection scheme 2 (2nd order central) to advect a domain filling tracer 
field (360 by 40 degrees domain). Running for on the order of a year, 
with a time step of 360 secs.

I need to do some very high diffusion runs, and Kh = 2000m2/s works 
fine, but Kh=4000m2/s and anything higher blows up - after one week 
there is a large patch of NaN/inf values and the whole tracer field 
becomes NaN by week 4.

Colleagues have carried out similar calculations at Kh = 1e4m2/s on 
previous MITgcm versions - any hints as to what might be going wrong? 
The runs that don't blow up behave as expected.

Thanks,
Emma
-- 
*Emma Boland*
Physical Oceanographer

The British Antarctic Survey
High Cross, Madingley Road
Cambridge
CB3 0ET
/01223221276/


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