[MITgcm-support] Question about closing heat budget
jwenegrat at stanford.edu
Wed May 4 22:45:46 EDT 2016
First off let me thank everyone who has contributed to the MITgcm and
the mailing list. It's a great tool, and I've gotten quite a bit of help
already digging through the mailing list archive.
I am currently running a simple reentrant channel model of a front, and
finding that while the momentum budget closes nicely following previous
advice found in the archive, closing the heat budget is proving more
To date I've followed the instructions posted here for closing the heat
Specifically, considering only subsurface grid cells (and with no
TOTTTEND/86400 = ADV_Tend + KPP_Tend + DIFF_Tend
Where ADV_tend = d/dx ADVx_TH + d/dy ADVy_TH + d/dz ADVr_TH (accounting
for cell volume in calculating this).
KPP_Tend = d/dz KPPg_TH (accounting for cell vol).
DIFF_Tend = d/dx DFxE_TH + d/dy DFyE_TH + d/dz DFrE_TH+ d/dz DFrI_TH
(accounting for cell volume)
I find that this balance works well at the beginning of my simulation,
works quite poorly in the middle (when the flow goes baroclinically
unstable), and then works reasonably well again towards the end as the
front spins down, although it is not completely closed.
Specific questions are:
1) I am using tempAdvScheme: 33, which I gather from the documentation
has associated diffusion which can be difficult to diagnose. Does the
associated diffusive flux from this end up within any of the above
diagnostics? Might this be the cause of the large residuals after the
formation of sharp frontal regions?
2) The tendency term appears to be a small residual between the
across-channel (y) and vertical flux divergences. As the features
sharpen to near grid-scale, might the finite differencing (and later
interpolation back to the tracer grid points) be causing problems?
More generally any suggestions of avenues to pursue would be greatly
appreciated. I'm not sure how the mailing list deals with attachments,
so I haven't included my data file, but can easily do so if useful.
Dept. of Earth System Science
Email: jwenegrat at stanford.edu
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