Dear all Gstat users,
I need some help about zonal anisotropy with Gstat.
- I could't exactly understand what s stands for in variogram model c
Mod(a,p,s) while defining zonal anisotropy. I mean: in Gstat manual it
is said to use a large anis ratio (s) while defining zonal anisotropy
but the subsequent example shows a very little ratio: which of the two?
Can s be interpreted as sill ratio instead of range ratio in this case?
- Is it possible to model both zonal and geometric anisotropy in Gstat,
having both of them in my data set, sometimes in the same direction,
some others in different ones? Which is the way to accomplish it?
- Is it correct to fit the variogram model once I found out which type
of anisotropy I have and established model parameters (a,p,s known)? If
the case, should I fit in total direction or along p direction (I think
total direction, because the model already contain an angular definition
of main continuity -p)? If not the case, should I use it as it is to
kriging?
- In the last case, if I don't have to fit the model and I've a
geometric anisotropy, how can I choose the correct sill, given that
they're not the same in both main range direction and minor direction?
Should I use the sill of major direction?
Thank you so much for help.
---
Giovanni De Ferrari
