Pull NLDAS Data Rods

nldas_rods.R

httr::GET("https://ldas.gsfc.nasa.gov/sites/default/files/ldas/nldas/NLDAS_masks-veg-soil.nc4",
          httr::write_disk("NLDAS_masks-veg-soil.nc"))

f <- "NLDAS_masks-veg-soil.nc"

meta <- ncmeta::nc_meta(f)

meta$variable

mask <- stars::read_ncdf(f, var = "NLDAS_mask")

stars::st_dimensions(mask)

lon <- stars::st_get_dimension_values(mask, which = "lon")
lat <- stars::st_get_dimension_values(mask, which = "lat")

p <- c(-90, 40)

nearest <- function(x, y) {
  z <- abs(x - y)
  
  which(z == min(z))[1]
}

X <- nearest(p[1], lon)
Y <- nearest(p[2], lat)

u <- paste0("https://hydro1.gesdisc.eosdis.nasa.gov/daac-bin/access/timeseries.cgi",
            "?variable=",
            "NLDAS:NLDAS_FORA0125_H.002:TMP2m",
            "&location=",
            "NLDAS:X", stringr::str_pad(X, 3, "left", "0"), "-Y", stringr::str_pad(Y, 3, "left", "0"),
            "&startDate=", 
            "2015-01-01T00",
            "&endDate=",
            "2015-06-20T23",
            "&type=", 
            "asc2")

asc <- httr::GET(u)

parse_list <- function(x) {
  lapply(x, function(y) {
    y <- strsplit(y, "=")[[1]]
    out <- list()
    out[[y[1]]] <- y[2]
    out
  })
}

parse_asc2 <- function(asc) {
  asc <- rawToChar(asc$content)
  asc <- strsplit(asc, "\n")[[1]]
  
  headers <- list(f = parse_list(asc[3:21]), d = parse_list(asc[24:38]))
  
  d <- read.table(text = asc[40:length(asc)], sep = "\t")
  
  return(list(headers = headers, data = d))
}