[R] "Rotated Lat-Lon" projection in mapproj

From: Victor Homar <victor.homar_at_uib.cat>
Date: Wed, 09 Jul 2008 20:31:36 +0200


I'm trying to plot a field obtained from the atmospheric model WRF-NMM which uses a "Rotated Lat-Lon¨ map projection. The WRF documentation mentions that:
· Rotates the earth's lat/lon grid such that the intersection of the
equator and prime meridian is at the center of the model domain.

· Within the rotated framework the grid spacing is constant, but in an
earth-relative sense, the scale varies slightly.

I haven't identified a projection in library mapproj that can handle this.

Any ideas on how to plot this field on a map?

A typical R script to plot other outputs in a lambert projection would be:

##Read lat/lon data
lat<-as.numeric(system(paste(pycmd,'control',"200108150000","LATITCRS",1,0,sep=" "),intern=TRUE))

lon<-as.numeric(system(paste(pycmd,'control',"200108150000","LONGICRS",1,0,sep=" "),intern=TRUE))

## Projected coordinates



## Plot map
filled.contour(xs,ys,Tsd[,,tstep],levels=fillevs,col=cpal,plot.axes={ map('world',projection="lambert",parameter=c(60.,30.),add=TRUE,col="grey"); contour(xs,ys,Tm[,,tstep]-273.15,levels=c(-20:20)*3,add=TRUE); axis(1,labels=F,tick=F);axis(2,labels=F,tick=F)},main=title) #,asp=1.)

Appreciate your help in advance,


Víctor Homar Santaner
Grup de Meteorologia

Edif. Mateu Orfila                      Tel: +34 971 17 1376
Universitat de les Illes Balears        Fax: +34 971 17 3426
07122 Palma de Mallorca (SPAIN)         Email: Victor.Homar_at_uib.es

              Knowledge is contagious. Infect truth.

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Received on Wed 09 Jul 2008 - 19:15:30 GMT

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