I am beginner in R. I had found in the literature that prior to performing kriging on the data, the distribution has to be investigated to check if it is Gaussian.
So, in order to check if the data follows Gaussian I plotted the quantile-quantile plot of rainfall for all days using data from 50 stations.
So, inorder to check if the data follows gaussian i plotted the quantile-quantile plot of rainfall for all days using N=50 stations data.
Shown below is the q-q plot for good rainy day.
The q-q plot of log transformed using transformation function : log(x+1)
Q-Q plot for bad(low) rainy day and its transformed plot are provided at to save space.. http://s20.postimage.org/a3kocwfgd/image.png
I have few basic questions:
- Though the fit of log-transformed data is good on good rainy days,it is not that on days where rainfall is scanty.
- How to back transform the data after interpolation?
- How to choose the block size in block kriging? any guidelines. I would like to compare the kriged value against the gridded rainfall from TRMM(25 km by 25 km)?