[aspect-devel] A bug in gplates plugin

[Siqi Zhang]

Hi All,

I found a bug in the gplates plugin.
While the gplate gpml file set longitude to 0 for all points at the pole,
the plugin assume the longitude vary from 0~360 for the grid points at two
poles. This gives the wrong cartesian velocity while reading the data and
result weird surface velocity field around the pole. I can create a bug fix
for this if Rene agrees.

And I have another question regarding the gplate plugin for Rene.
I have noticed that the interpolation method of this plugin has changed
from latitude-longitude grid interpolation using spherical velocity to
distant weight interpolation using cartesian velocity. I totally agree that
we should do interpolation using the cartesian velocity, but is there any
particular reason to use the distant weight instead of using four points
bilinear interpolation on the latitude-longitude grid?
Because while using the new interpolation in 3D model, I found some
artificial strain rate within plate, it gives me some trouble while I am
also using yielding stress in the rheology. After I reverse back to the old
grid approach and interpolate using the cartesian velocity, it seems
working better. Although it is not completely removed, the artificial
strain rate is much less than the new interpolation approach. I wonder if
anyone using this plugin experience the similar problem and if we need the
change the interpolation method again.


Regards,


-- 
Siqi Zhang

Research Associate
ARC Centre of Excellence for Core to Crust Fluid Systems (CCFS)
Department of Earth and Planetary Sciences
Macquarie University
NSW 2109

Telephone: +61 2 9850 4727
http://www.CCFS.mq.edu.au
http://www.GEMOC.mq.edu.au
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