%# fields  is a package for analysis of spatial data written for
%# the R software environment .
%# Copyright (C) 2018
%# University Corporation for Atmospheric Research (UCAR)
%# Contact: Douglas Nychka, nychka@ucar.edu,
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%# GNU General Public License for more details.
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\name{RCMexample}
\alias{RCMexample}
\docType{data}
\title{3-hour precipitation fields from a regional climate model}
\description{
These are few model output fields from the North American Regional Climate
 Change and Assessment Program (NARCCAP). 
 The imagea are transformed surface precipitation fields simulated by the WRFP
regional climate model (RCM) over North Amreica forced by observation
data. The fields are 3 hour precipitation for 8 time periods in January
1, 1979. The grid is unequally spaced in longitude and latitude  appropriate projection centered on the model
domain.The grid points are nearly equally spaced in great circle distance due to this projection. Precipitation is in a log 10 scale where values smaller than
4.39e-5 ( the .87 quantile) have been been set to this value. Longitudes have
 been shifted from the original coordinates (0-360) to the range (-180-180) that
is assumed by the R \code{map} function.
}
\usage{data(RCMexample)}
\format{
  The format is a list of three arrays:
\itemize{

\item  x: 123X101 matrix of the longitude locations 
\item  y: 123X101 matrix of the latitude locations 
\item  z: 123X101X8 transformed matrix of precipitation
}

Spatial units are degrees with longitude being -180,180  with the prime meridian at 0.
Precipitation is log 10 of cm / 3 hour period.
}
\details{
 This is primarily an example of a regular grid that is not equally
spaced and is due to transforming an equally spaced grid from one map
projection into longitude latitude coordinates. This model is one small
part of an extension series of numerical experiments the North American
Regional Climate Change and Assessment Program (NARCCAP). NARCCAP has
used 4 global climate models and observational data to supply the
atmospheric boundery conditions for 6 different regional climate
models. In the current data the forcing is the observations derived
from the NCEP reanalysis data and is for Janurary 1, 1979. The full
simulation runs for 20 years from this starting date. See
\url{www.image.ucar.edu/Data} for more information about these data.

To facilatate an animation of these fields the raw precipitation values 
have been transformed to the log scale with all values below 4.39E-5 cm/3 hours
set to this lower bound.  

}
\examples{
data(RCMexample)
# second time period

image.plot( RCMexample$x, RCMexample$y, RCMexample$z[,,2])
world( add=TRUE,  lwd=2, col="grey")

}
\keyword{datasets}