1802[ai-geostats] variogram analysis
- Dec 8, 2004Rajive
I haven't read the other responses yet, so this may be
(1) anisotropy: if this is shallow marine data there
should be a difference between longshore drift and
off-shore deepening of sea-bed. You have an
omni-directional semi-variogram. It is possible that
the sampling grid is irregular enough to be
highlighting directional differences??
(2) mega-ripples: I have seen similar behaviour in
off-shore marine diamonds which tend to hug the bottom
of trenches or ripples. Major ocean beds have
mega-ripples on the kilometre scale, which is what you
are seeing here.
More worrying, I would say, is the fact that your
graph is dropping with distance. This suggests that
you also have some underlying trend (non-stationarity)
which is causing closely spaced samples to be 'more
different' than those further apart.
I notice you are using a log transform. What does your
probability plot look like?
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