#This directory contains the monthly averaged time series and their anomaly time series for 
#TMT (MSU channel 2 and AMSU-A channel 5), TTS (MSU channel 3 and AMSU-A channel 7), and TLS 
#(MSU channel 4 and AMSU-A channel 9) derived from NOAA TIROS-N through NOAA-18 and MetOp-A and 
#NASA EOS Aqua. The grid resolution for these datasets is 2.5 degree latitude x 2.5 degree longitud

#1) Merged_Deep-Layer_Temperature: Merged monthly deep-layer temperature time series for TMT, TTS, and TLS. 
#   Christy bias correction was applied to further remove intersatellite biases after the SNO calibration. 
#   TMT and TLS: November 1978 - present.
#   TTS: January 1981 - present. 

#2) Anomaly_Time_Series: Monthly anomaly time series for TMT, TTS, and TLS. 
#   The temperature anomaly for each layer was generated using mean annual cycle for the period of 2000-2010.

#Merged Deep Layer
 #3 dsets of ~13 MB
 #2x3 dsets of 49 MB

#GLObal mean Anom
 # 3 dsets of 49 KB 

##DEC 2016
 #versions 3.0 and 4.0 
#ftp://ftp.star.nesdis.noaa.gov/pub/smcd/emb/mscat/data/MSU_AMSU_v3.0/
  #Merged Deep Layer/
#ftp://ftp.star.nesdis.noaa.gov/pub/smcd/emb/mscat/data/MSU_AMSU_v4.0/

#ftp://ftp.star.nesdis.noaa.gov/pub/smcd/emb/mscat/data/MSU_AMSU_v3.0/Monthly_Atmospheric_Layer_Mean_Temperature/
#two subdirectories:
  #Global_Mean_Anomaly_Time_Series/
  #Merged_Deep-Layer_Temperature/
#Merged_Deep-Layer are 45MB TLS, TMT, TUT 

#function retrieves AMSU5 from Monthly_Atmospheric_layer
#GLB MSU2,3, 4

get_noaa= function(tropo="TMT",zone="glb",mm="201611") {
require(ncdf4)
alias=c(TLT="MSU2",TMT="MSU3")
D=format(Sys.Date(),"%Y")

if(zone=="glb") {
# zone="glb"; tropo="TMT"
prefix="ftp://ftp.star.nesdis.noaa.gov/pub/smcd/emb/mscat/data/MSU_AMSU_v3.0/Monthly_Atmospheric_Layer_Mean_Temperature"
directory="Global_Mean_Anomaly_Time_Series" 
fred=download_html(file.path(prefix,directory))
y=fred[grep(alias[paste(tropo)],fred)]
z=strsplit(y,">")[[1]][2]
n=nchar(z)
suffix=substr(z,1,n-3)
loc=file.path(prefix,directory,suffix)
  download.file(loc,dest)
 #readLines(dest,n=10)
 work=read.table(dest,header=T)
 names(work)
	#[1] "Year"                 "Month"                "Ftime"                "Global_Mean_Anomaly"  "NH_Anomaly"          
	#[6] "SH_Anomaly"           "Global_Land_Anomaly"  "Global_Ocean_Anomaly"
  names(work)=c("yy","month","year","glb","nh","sh","land","ocean")
  work=ts(work,start=c(1978,11),freq=12)
  return(work)
}

if(zone=="trp") {
#this works for TMT; retrieving nc version
#there are dat versions for MSU2, MSU3, 
## loc="ftp://ftp.star.nesdis.noaa.gov/pub/smcd/emb/mscat/data/MSU_AMSU_v3.0/Monthly_Atmospheric_Layer_Mean_Temperature/
# tropo="TMT";zone="trp"
prefix="ftp://ftp.star.nesdis.noaa.gov/pub/smcd/emb/mscat/data/MSU_AMSU_v3.0/Monthly_Atmospheric_Layer_Mean_Temperature"
directory="Merged_Deep-Layer_Temperature"
fred=download_html(file.path(prefix,directory))
y=fred[grep(tropo,fred)]
y=y[grep("nc",y)]
z=strsplit(y,">")[[1]]
n=nchar(z[2])
suffix=substr(z[2],1,n-3)
 download.file(file.path(prefix,directory,suffix),dest,mode="wb")
 v=nc_open(dest)
 work=ncvar_get(v)
 dim(work)
  #[1] 144  72 449
  #v$dim$lat$vals # S to N
  #v$dim$lon$vals # -180- 180
 temp= abs(v$dim$lat$vals)<=20;sum(temp) #16
 nc_close(v)

 out=apply(work[,temp,],3,mean)
 out=ts(out,start=c(1978,11),freq=12) #absolute temperature
 return(out)
 } #trp
}

#noaa_trp=out