[MITgcm-support] diagnosing problems with the adjoint

[Holly Dail]

Thanks for the advice Matt.

I'm not using the divided adjoint, but I'll try the  
autodiff_inadmode_set.F approach.

Here are the viscosities / diffusivities (chosen to be almost exactly  
that used in ECCO):
  viscAz=1.E-3,
  viscAh=1.E4,
  diffKhT=100.,
  diffKzT=2.E-5,
  diffKhS=100.,
  diffKzS=1.E-5,

I used your advection scheme based on your earlier advice, but haven't  
tried
> multiDimAdvection=.FALSE.,
Will try that too.

My time step is 3600 - again same as ECCO.

Thanks -
Holly


On Aug 12, 2009, at Aug 12 , 11:42 AM, Matthew Mazloff wrote:

> Hi Holly,
>
> Your adjoint is definitely blowing up (how many timesteps is your  
> grad check....its blowing up fast).   Try turning off packages when  
> you run the adjoint and see if that helps.  Are you using the  
> divided adjoint?  If so you can just change some things to false in  
> data.pkg when its about to start.  Turn off KPP and GMREDI and  
> packages of that nature.  If you are not using the divided adjoint  
> then you have to use autodiff_inadmode_set.F to turn these things  
> off.  In this file just set
>      usePtracers  = .FALSE.
>      useKPP = .FALSE.
>      useGMREDI = .FALSE.
>      useSEAICE = .FALSE.
>
> Then try again
>
> -Matt
>
> ps> out of curiosity, what viscosity and diffusivity are you trying  
> to run the adjoint with?
>
> Oh, and also some of the advection schemes may not be stable.  I am  
> using
> multiDimAdvection=.FALSE.,
> tempAdvScheme=30,
> saltAdvScheme=30,
>
>
>  pps> of course the real expert is just upstairs from you -- bug  
> him :o)
>
>
>
>
> On Aug 12, 2009, at 8:14 AM, Holly Dail wrote:
>
>> Hello all -
>>
>> I'd like to use optimization with a regional North Atlantic setup.   
>> As a first case, I started with the approach laid out in  
>> tutorial_global_oce_optim --
>> - cost based on (1) divergence of annual mean surface temperatures  
>> in the model from climatology and (2) reasonable magnitude of  
>> control vector
>> - control is a time-mean heat flux correction (2-d field)
>>
>> My sensitivities are astronomical (i.e. adxx = 10^16), the gradient  
>> check seems to fail (as shown below, finite difference gradients  
>> seem okay, adjoint gradients not so much), and optim.x fails with  
>> message 'the linesearch failed'.
>>
>> (PID.TID 0000.0001) grdchk output:            procId                
>> I        ITIL  EPOS        JTILEPOS           LAYER             
>> X(I)      X(I)+/-EPS
>> (PID.TID 0000.0001) grdchk output:            FC              
>> FC1             FC2 FC1-FC2/(2*EPS)    ADJ GRAD(FC)   1-FDGRD/ADGRD
>> (PID.TID 0000.0001) grdchk output:                 0                
>> 1             56              35               1 0.000000000D+00 -. 
>> 100000000D+00
>> (PID.TID 0000.0001) grdchk output:                   0.261232434D 
>> +02 0.261232444     D+02 0.261232340D+02 0.523051129D-04 -. 
>> 115313924+108 0.100000000D+01
>>
>> I suppose this may mean the adjoint is blowing up?  I've tried  
>> reducing my time step and increasing viscosity and I checked that  
>> my climatology & error fields are defined at all wet points; are  
>> there other fixes folks have had success with?  Also if you have  
>> scripts that you use to diagnose your optimization runs that would  
>> be really appreciated.
>>
>> Thanks -
>> Holly
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>> MITgcm-support at mitgcm.org
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