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

[Victor Homar]

Hi,

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
coords_lamb<-mapproject(lon,lat,projection="lambert",parameters=c(60.,30.))

xs<-t(matrix(coords_lamb$x,ncol=NCC,nrow=NRC))[,1]

ys<-t(matrix(coords_lamb$y,ncol=NCC,nrow=NRC))[1,]}

## 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.

-- 
-----------------------------------------------------------------------
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.