##12 CRU NH #potential target 1961-1990

#http://www.cru.uea.ac.uk/cru/data/temperature/crutem3nh.txt
#http://www.metoffice.gov.uk/hadobs/crutem3/diagnostics/hemispheric/northern/

get.crutem=function(dset="cru",hemi="nh",annual=FALSE) {
  if(dset=="cru") {
	url<-paste("http://www.cru.uea.ac.uk/cru/data/temperature/crutem3",hemi,".txt",sep="")  #1850 2008 
	h<-scan(url)
	start0<-h[1]
	N<-length(h)
	h<-array(h,dim=c(27,N/27))
	h<-t(h)
	crutem3=ts(c(t(h[,2:13])),start=c(1850,1),freq=12)
	temp=(crutem3==0)&(time(crutem3)>=floor(tsp(crutem3)[2]))
	crutem3[temp]=NA
	if(annual) crutem3<-ts(h[,14],start=start0) #1850 - 
	crutem3=window(crutem3,end=max( time(crutem3)[!is.na(crutem3)]) )
	return(crutem3)
   }
  if(dset=="had") {
	alias=c(gl="global/nh+sh",nh="hemispheric/northern", sh="hemispheric/southern")
	url=paste("http://hadobs.metoffice.com/crutem3/diagnostics/",alias[hemi],"/nh+sh/monthly",sep="")
  	D=read.table(url) #dim(D) #158 12 #start 1850
    	names(D)=c("mm","anom","u_sample","l_sample","u_coverage","l_coverage","u_bias","l_bias","u_sample_cover","l_sample_cover",
    		"u_total","l_total")
	N=nrow(D)
	D$year=as.numeric(substr(D$mm,1,4))
	D$month=as.numeric(substr(D$mm,6,7))
	D$mm=100*D$year+D$month
	if (sum( !is.na(match( diff(D$month),c(1,-11))) ) ==0  ) crutem3=ts(D[,2],start=c(1850,1),freq=12) else {	
	  x=ts(NA,start=c(1850,1),end=c(D$year[N],D$month[N]),freq=12) 
	  M=length(x);month= (1:M)%%12; month[month==0]=12;year=floor(time(x))
	  timegrid= 100*year+month
	  test=match(timegrid,D$mm);temp=!is.na(test)
	  x[temp]=D$anom[test[temp]]  
	crutem3=x }
	if(annual) crutem3=annavg(crutem3)
	return(crutem3)
   }
}


#	
#	crutem=get.crutem.hemi(dset="cru",hemi="nh",annual=TRUE)
#	crutem[["had"]]=get.crutem.glb(dset="had")
#	cru=ts.union(crutem[[1]],crutem[[2]])
#	plot.ts(cru[,1]-cru[,2])