[ecco-support] [EXTERNAL] Request for a specific configuration of ECCOv4

[Matthew Mazloff]

I see - this makes sense.

Though I agree with Dimitris. The adjoint only gives sensitivities in a perturbation sense. I do see the value of removing the strong nonlinearities in the bulk formulae, but the entire system is nonlinear (e.g. the transmission of those fluxes through the mixed layer) so you are never decoupling the flux components beyond that perturbation scale.

Matt



> On Apr 6, 2020, at 8:10 AM, Dimitris Menemenlis <menemenlis at jpl.nasa.gov> wrote:
> 
> I agree but maybe call it “linear dependence” instead of “double counting”.  Although this linear dependence may be stronger between atmospheric variables that are used as input for bulk formulae, there is also non-zero linear dependence between surface fluxes.
> 
>> On Apr 3, 2020, at 6:53 AM, Dan Jones <dcjones.work at gmail.com <mailto:dcjones.work at gmail.com>> wrote:
>> 
>> Hi Dimitris,
>> 
>> Although I could be wrong, I do not think that the potential double counting issue matters much for the adjoint optimization process. As long as the control adjustments reduce the cost function, then I suppose that the optimization process will still work. Do you agree?
>> 
>> However, if we are attempting to reconstruct an objective function using adjoint sensitivities and anomalies (e.g. Helen Pillar's work on RAPID time series reconstructions, see her 2016 J. Climate paper), then the potential double-counting could be an issue. I'm hoping that by avoiding the bulk formulae I can more cleanly separate the effects of wind stress anomalies from those of heat flux anomalies. 
>> 
>> Best,
>> Dan
>> 
>> --------------------------------------------------------------
>> Dr Dan Jones / British Antarctic Survey
>> danjonesocean.com <http://www.danjonesocean.com/> / @DanJonesOcean
>> --------------------------------------------------------------
>> _______________________________________________
>> ecco-support mailing list
>> ecco-support at mit.edu <mailto:ecco-support at mit.edu>
>> http://mailman.mit.edu/mailman/listinfo/ecco-support
> 
> _______________________________________________
> ecco-support mailing list
> ecco-support at mit.edu
> http://mailman.mit.edu/mailman/listinfo/ecco-support

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.mit.edu/pipermail/ecco-support/attachments/20200406/93cbc6c4/attachment.html