[R-sig-Geo] Co-Kriging with huge data

[Edzer Pebesma]

Kai Zhang wrote:
> Dear all,
>
> I have temperature measurements at 17 monitors.  I have a secondary variable across the study area, which includes 230,000 points. I tried to conduct Co-Kring with this huge dataset and it appeared to be computationally intensive. Is there any way to run it except for running the program in a cluster?
>
> I appreciate your response and best regards,
> Kai
>   
One alternative would be to use co-kriging and to limit the search
neighbourhood for the secondary variable. The question is how much.
Maybe a cross validation with your 17 temperature monitors can give you
some idea on this. If someone knows about existing literature on this,
I'd be happy to hear.

Another possibility is to use universal kriging, with your secondary
variable treated as predictor. For this, you need the values of your
secondary variable to be known ath the 17 monitor sites, and the
prediction locations should coincide with (some of) the 230000 points.
It is not equivalent to the first approach, poorer in the sense that it
ignores the secondary variable at locations beyond the prediction
location, but assumes a linear relationship between the two as well.

-- 

Edzer Pebesma
Institute for Geoinformatics (ifgi), University of Münster 
Weseler Straße 253, 48151 Münster, Germany. Phone: +49 251 
8333081, Fax: +49 251 8339763  http://ifgi.uni-muenster.de 
http://www.52north.org/geostatistics      e.pebesma at wwu.de