[Mitgcm-support] advection schemes

[mitgcm-support at dev.mitgcm.org]

Hi again,

this time I have a question about advection schemes:
I have replaced the default advection (2nd order, centered) by the DST-3 
with flux limiter (temp/salt/tracerAdvScheme=33, by the way, not very 
well documented which idenifying number belongs to which scheme). In my 
channel, I start from a zonally homogeneous (symmetric) state, with a 
strong vertical stratification (similar to Wardle and Marshall, 2000, JPO).

I expect (and this is true for the 2nd centered scheme) that, starting 
from rest, I spinup my channel ad infinitum, until the CFL criterium is 
violated the model explodes.

With the DST-3 with flux limiter, this is NOT what happens, instead the 
whole system becomes unstable almost immediately (even if I have some 
explicity bi-harmonic friction), I get deep mixing until the channel is 
basically homogenized and then slowly the flow restratifies according to 
my buoyancy forcing, but the zonal symmetry is broken forever. Is that 
supposed to happen?

Martin

-- 
Martin Losch
Alfred Wegener Institute for Polar and Marine Research
Postfach 120161, 27515 Bremerhaven, Germany;
Tel./Fax: ++49(0471)4831-1872/1797