[CIG-SEISMO] time reversed computation in specfem2d

[Dimitri Komatitsch]

Dear Jörg and Carl,

This has been done already, by Carl Tape et al. from Caltech (USA).
See for instance their papers below and in PDF at 
http://www.gps.caltech.edu/~carltape/research/CV.html#Pubs

I thought the kernel capability and adjoint runs had been added to 
SPECFEM2D already (on the SVN server). Carl, did you do it?
We talked about it (merging your kernels in the SVN code) two years ago
and I thought that it had been done since then. If not, would it be easy 
to do? It would clearly be very useful. As always, working on a local 
version not under SVN control was a bad idea to begin with... because 
now it is a dead branch... could somebody (maybe Jörg) cut and paste 
your adjoint routines in the SVN code? (if you sent him a copy of your 
old 2D code)

In the future let us all use SVN all the time from the beginning of any 
new SPECFEM project.

Thanks,
Cheers,

Dimitri.

Tape, C., Liu, Q., and J. Tromp, 2007, Finite-frequency tomography using 
adjoint methods---Methodology and examples using membrane surface waves, 
  Geophysical Journal International, v. 168, 1105-1129.


Tromp, J., Tape, C., and Q. Liu, 2005, Seismic tomography, adjoint 
methods, time reversal, and banana-doughnut kernels, Geophysical Journal 
International, v. 160, p. 195-216.


pge05bqw at studserv.uni-leipzig.de wrote:
> Hello,
> i'am trying to add a time reversed computation to specfem2d. First I  
> thought it would be enough to change sign of deltat(and deltatcube...)  
> after some time iteration steps(e.g. half of NSTEP). But it doesn't  
> seem to be that easy, because it leads to a extremly big maximum norm  
> of vector field, which aborts the program.
> Does anyone have an idea how this could work?
> Thanks,
> Jörg Buchwald
> Student
> University of Leipzig
> 
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-- 
Dimitri Komatitsch - dimitri.komatitsch aT univ-pau.fr
Professor, University of Pau, Institut universitaire de France,
CNRS and INRIA Magique3D, France   http://www.univ-pau.fr/~dkomati1