[aspect-devel] Dynamic Topography vs Topography

[Rene Gassmoeller]

Hi Payman,

I guess the short answer is: They do different things. The topography
postprocessor measures the actual deformation of the mesh (i.e. you will
only see significant values, if you use a deforming mesh / free
surface). The dynamic topography however is calculated as: How much
topography would be here, if the pressure were to be balanced by
overlying topography (for a longer explanation including formulas take a
look at the postprocessor description in the manual or the source code).

So as long as you do not use a free surface, the values of the
'topography' postprocessor will be close to zero (there might be a tiny
value). And if you use a free surface the 'dynamic topography'
postprocessor will likely no longer calculate anything useful (because
the pressure is already compensated by building a topography).

Hope that helps,

Best,

Rene


On 11/06/2016 01:58 PM, Payman Janbakhsh wrote:
>
> Hi
>
> When running a model, postprocessor outputs min and max topography at
> the end of each time step. In my case shows  values around + - 1.5m
>  (early steps).
>
> Then when using dynamic topography postprocessor to plot dynamic
> topography vs X, with or without the option of Subtract mean of
> topography, my plot  shows values between -150m to 200m in some areas
> and zero(in the case of subtracted mean)  for the rest of the x
> dimension.
>
> Why is there a discrepancy between Topography min/max  and dynamic
> topography at the same time step? Shouldn’t the topography min/max
> reflect the min /max on my dynamic topography plot?
>
>  
>
> Thank you
>
>  
>
> Payman
>
>
>
> _______________________________________________
> Aspect-devel mailing list
> Aspect-devel at geodynamics.org
> http://lists.geodynamics.org/cgi-bin/mailman/listinfo/aspect-devel

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.geodynamics.org/pipermail/aspect-devel/attachments/20161107/32b0937a/attachment.html>