I have a dataframe named seoul315 contains the 107 data of PM10 concentration at 1 march,2012,5.00 am. please, download. I have tried to plot semi-variogram for kriging bt the following code:
library(sp)
library(gstat)
library(rgdal)
seoul315<-read.csv("seoul315.csv")
seoul315<-na.omit(seoul315)
hist(seoul315$PM10) #Data are not in Gaussian form.So need to log transform
hist(log(seoul315$PM10))
coordinates(seoul315)<-~LON+LAT
proj4string(seoul315) = "+proj=longlat +datum=WGS84"
seoul315<-spTransform(seoul315, CRS("+proj=utm +north +zone=52 +datum=WGS84"))
#plot Omnidirectional Variogram
seoul315.var<-variogram(log(PM10)~1,data=seoul315,cutoff=80000, width=10000)
seoul315.var
plot(seoul315.var, col="black", pch=16,cex=1.3,
xlab="Distance",ylab="Semivariance",
main="Omnidirectional Variogram for seoul 315")
#Model fit
model.315<- fit.variogram(seoul315.var,vgm(psill=0.11,model="Gau",range=60000/sqrt(3),nugget=0.04),
fit.method = 6)
plot(seoul315.var,model=model.315, col="black", pch=16,cex=1.3,
xlab="Distance",ylab="Semivariance",
main="Omnidirectional Variogram for seoul 315")
#Directional Variogram
seoul315.var1<-variogram(log(PM10)~1,data=seoul315,width=10000,cutoff=80000,
alpha=seq(0,135,45),tol.hor=15)
plot(seoul315.var1,model=model.315, cex=1.1,pch=16,col=1,
main="Anisotropic Variogram for PM10")
I got the directional variogram like this:
But from this variogram I can see sill are not same in all direction that means its zonal anisotropy. I think in this case I can't use anis()
function which I used to remove the geometric anisotropy. How can I remove the zonal anisotropy for using the variogram in kriging? Is it possible by using gstat in R?
Actually I can't find the proper way for doing this after rigorous searching. If you need further information please let me know.