[MITgcm-support] obcs adjoint issue (I need dynamics.F help)

[Martin Losch]

Hi Matt,

I have no time to look into this right now, but I suggest, that you  
try it yourself: use exp4 and see whether keeping removing the extra  
calls to obcs_apply_uv change the result (by running ./testreport -q - 
t exp4). If removing a call does change the result, then this call is  
necessary. (I believe exp4 does not use the vector invariant moment  
equations, but you can put that in for your tests and have an extra  
personal verifcation experiment for that case, too).

Are you sure that the odd structions in adgv does not have other  
origins?

Martin
On 9 Nov 2006, at 02:41, Matthew Mazloff wrote:

> Hello,
>
> I have been using the open boundary controls.  The sensitivities  
> for the velocity normal to the boundary appear unphysical.  (I am  
> using a northern boundary so for my case V is the normal vel.)  I  
> have tracked down what is causing this.  It is that on the open  
> boundary the adjoint variable of gV has an odd structure.  And  
> because dynamics.F calls OBCS_APPLY_UV twice, this odd structure  
> gets added to the sensitivities twice.  Calling  OBCS_APPLY_UV( bi,  
> bj, k, gU, gV, myThid ) is rather benign in the forward  
> integration, U and V on the open boundary get written over anyway.   
> In the adjoint integration, however, every call matters.  Could  
> someone more expert in the dynamics.F routine please check if all  
> these calls are necessary.  And I'd really appreciate it if they  
> could also fill me in as to why they are there.
>
> Thanks,
> Matt
>
> ps> I'm using vectorInvariantMomentum and implicitViscosity
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