[CIG-SEISMO] time reversed computation in specfem2d

[pge05bqw at studserv.uni-leipzig.de]

Hello,
thanks for your answers. My aim is to simulate time reversed seismic  
wave propagation in random media. There should be absorbing and non  
absorbing bounderies. This is in preparation for my physics diploma  
thesis. I'm sorry if I ask silly questions because I'm quite new to  
(computational) geophysics.
How does the source function matter for the adjoint simulation, if I  
run a forward simulation first? (The temporal extent of the source  
function should of course be small compared to the running time)I  
thought it would be enough to change the sign of the "deltat" in the  
second loop only. (which seems to work for the only time loop in 1D)  
The routines of the 3D adjoint code appear to be much more complicated  
than that.
But if someone of you has allready implemented it, it would be nice if  
you could make it available.
Best regards,
Jörg

Zitat von Chris Morency <cmorency at Princeton.EDU>:

> Hi,
>
> Can you give me some more specificities about your experiment ? You  
> said you are running a time reversed experiment. How do you define  
> your source function ?
> Do you have absorbing boundaries ? Is a homogeneous/heterogeneous model ?
>
> For your information, we are upgrading specfem2D. The new package  
> will have acoustic/elastic/poroelastic capabilities, adjoint method  
> and Frechet derivatives calculation will also be included.
>
> Christina
>

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