Ray,

It is probably "Teale-Albers" (the commonly used projection used in
California) with NAD83 or NAD27 datum.

"+proj=aea +lat_1=34 +lat_2=40.5 +lat_0=0 +lon_0=-120 +x_0=0 +y_0=-4000000
+ellps=GRS80  +units=m  +datum=NAD83"

or

"+proj=aea +lat_1=34 +lat_2=40.5 +lat_0=0 +lon_0=-120 +x_0=0 +y_0=-4000000
+ellps=clrk66 +datum=NAD27 +units=m +no_defs"

(see: http://www.spatialreference.org/ref/?search=teale+)


Robert



On Tue, Dec 13, 2011 at 1:32 PM, Ray Danner <danner.ray@gmail.com> wrote:

> Dear community,
>
> I would like to calculate average values from a few hundred raster
> files and then query values for 217 specific points.  The raster files
> are of evapotranspiration data in California
> (http://goes.casil.ucdavis.edu/cimis/).  The maps have 2km resolution.
>  I'm able to download the .asc files, visualize them, average them,
> and query point values, but can't get the maps into the proper
> coordinate system so that I can query points based on decimal degrees.
>  The website states that the maps are in Albert's Equal Area
> projection (http://goes.casil.ucdavis.edu/), though doesn't provide
> any reference points (not sure if these are necessary).  Would anyone
> be willing to point me in the correct direction regarding coordinate
> systems?  Please see example below.
>
> Thanks in advance.
> Ray
>
> #download:
> http://goes.casil.ucdavis.edu/cimis/2011/01/04/mc_et0_avg.asc.gz
> library("maptools")
> library("raster")
> grid <- readAsciiGrid("/Users/rdanner/Downloads/mc_et0_avg.asc")
> table <- data.frame(grid)
> image(grid)
> ETo<-raster(grid)
> plot(ETo) #Note that the scale is not decimal degrees
>
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