#Mask

get_landmask=function(dset=2.5) {
 if(dset==5) {
	require(ncdf)
	loc="ftp://ftp.cdc.noaa.gov/Datasets/noaamergedtemp/lsmask.nc"	
	download.file(loc,"temp.dat",mode="wb")
	v<-open.ncdf("temp.dat")
	names(v$var) # [1] lsmask
	mask <- get.var.ncdf( v, v$var[[1]]) # 1880 2008
	dim(mask) # 72 36
	names(v$dim) #[1] "time"  "lat"   "lon"   "nbnds"
	v$dim$lat$vals # 87.5N to 87.5S
	v$dim$lon$vals # 177.5W to 177.5E
	#range(mask) #0 to 1
	return(mask)
  }

if(dset==2.5) {
	download.file("http://www.climateaudit.info/data/satellite/landmask_2.5.dat","temp")
  	  #scraped from http://mynasadata.larc.nasa.gov/las/getUI.do	
	loc="temp"
	mask=read.fwf(loc,widths=c(6,5,rep(7,144) ),skip=3 )
	row.names(mask)=as.character(mask[,1])
	mask=mask[,3:ncol(mask)] #72 144
	dimnames(mask)[[2]]=seq(-178.75,178.75,2.5)
	mask=as.matrix(mask[nrow(mask):1,]) #S to N 
	mask[mask==2]=.5 #coastal
	return(mask)
}

######################
  if(dset==2) {
	require(ncdf)
	url="http://jisao.washington.edu/data/ersst/ersstlandmask.nc"
	download.file(url,"Temp.nc",mode="wb")
	v=open.ncdf("Temp.nc")
	mask <- get.var.ncdf( v, v$var[[1]] ); #this is different than other versions
	dim(mask) # [1] 180  89	
	mask=mask[c(91:180,1:90) ,89:1] 
	image.plot (seq(-179,179,2),seq(-89,89,2),mask)
	#save(mask,file="d:/climate/data/gridcell/mask_2deg.tab")
	return(mask)
  }

##ONE DEGREE
  if(dset==1) {
	require(ncdf)
	loc="ftp://ftp.cdc.noaa.gov/Datasets/noaa.oisst.v2/lsmask.nc"
	download.file(loc,"temp.nc",mode="wb")
	v=open.ncdf("temp.nc")
	mask <- get.var.ncdf( v, v$var[[1]] ); #this is different than other versions
	dim(mask) # [1] 360 180
	mask=mask[,180:1]
	#contour(1:360,1:180,mask)
	return(mask)
   }	


##QUARTER DEGREE
 if(dset==0.25) {
	loc="http://ldas.gsfc.nasa.gov/gldas/data/0.25deg/UMD60mask0.25.asc"
	download.file(loc,"temp")
	mask=read.table(loc)
	names(mask)=c("grid","item","lat","long","mask")
	dim(mask)
	return(mask)
  }

}