[MITgcm-support] diagnosing problems with the adjoint
hdail at MIT.EDU
Wed Aug 12 13:17:08 EDT 2009
I don't know how to check the testreport, but I did run the tutorial.
I had to make two changes -- I switched to synchronous time stepping
(1800 sec) based on Patrick's advice, and I set the tutorial to run
for a year.
The adjoint doesn't blow up, but I am still struggling with some
- if I use a March 2009 version of the GCM, optim.x ends with iter0 at
a cost of 14.66 and iter1 at a cost of 12.04; optim.x stops based on
maximal number of iterations reached which seems to be in line with
what you got when you developed this tutorial.
- if I use a current version of the GCM, optim.x ends with iter0 again
at a cost of 14.66, but iter1 fails to reduce cost with a message 'the
search direction is not a descent one'
I did recompile and retest the March version this week to make sure
this was the case even with fresh compiles of both, and indeed it is.
Not sure what could have changed in the GCM; I couldn't find anything
significant in the tutorial code or config, lsopt, optim, or any of
the packages I thought to check.
On Aug 12, 2009, at Aug 12 , 12:49 PM, David Ferreira wrote:
> Just to be sure: does the testreport of tutorial_global_oce_optim
> run fine for you ?
> Holly Dail wrote:
>> 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):
>> I used your advection scheme based on your earlier advice, but
>> haven't tried
>> Will try that too.
>> My time step is 3600 - again same as ECCO.
>> Thanks -
>> 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
>>> 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
>>> 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 -
>>>> MITgcm-support mailing list
>>>> MITgcm-support at mitgcm.org
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