[MITgcm-devel] stripes in adjoint along tile edges

[Martin Losch]

Hi adjoint people,

while debugging, I stumbled over interesting stripes in the adjoint fields along tile edges. See attached files for an example (based on arctic_cs36 with 24 cpus, sNx = 35, sNy = 48), log10(sqrt(adU**2)) for layers 1 and 10 after 1 adjoint timestep (after evaluating the cost function). As a cost function I evaluate theta(80,30), at the spot with the highest sensitivity. The stripes have low magnitudes (1e-8), but still large compared to the surrounding values. Does that look familiar in any way? Should I be worried about this? (I am because the model later explodes along these stripes). 

Martin

PS. I am using cdTargetResidual=1e-13 and cg2dMaxIters=1000, and these stripes appear when the seaice package is turned off totally (forwards and backwards), with advection scheme 30 and 33 for T/S.


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mitgcm.org/pipermail/mitgcm-devel/attachments/20141120/d759f1ae/attachment-0001.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: adU_k1_t1.png
Type: image/png
Size: 58023 bytes
Desc: not available
URL: <http://mitgcm.org/pipermail/mitgcm-devel/attachments/20141120/d759f1ae/attachment-0002.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: adU_k10_t1.png
Type: image/png
Size: 47444 bytes
Desc: not available
URL: <http://mitgcm.org/pipermail/mitgcm-devel/attachments/20141120/d759f1ae/attachment-0003.png>