[MITgcm-devel] stripes in adjoint along tile edges

[Dimitris Menemenlis]

could that be caused by insufficient overlap regions?

> On Nov 20, 2014, at 7:28 AM, Martin Losch <Martin.Losch at awi.de> wrote:
> 
> 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.