R/sounding_wyoming.R

In climate: Interface to Download Meteorological (and Hydrological) Datasets

#' Sounding data
#'
#' Downloading the measurements of the vertical profile of atmosphere (also known as sounding data). Data can be retrieved using TEMP and BUFR sounding formatting.
#'
#' @param wmo_id international WMO station code (World Meteorological Organization ID); For Polish stations: Łeba - 12120, Legionowo - 12374, Wrocław- 12425
#' @param yy year - single number
#' @param mm month - single number denoting month
#' @param dd day - single number denoting day
#' @param hh hour - single number denoting initial hour of sounding; for most stations this measurement is done twice a day (i.e. at 12 and 00 UTC), sporadically 4 times a day
#' @param min minute - single number denoting initial minute of sounding; applies only to BUFR soundings. 
#' @param bufr - BUFR or TEMP sounding to be decoded. By default TEMP is used. For BUFR soundings use `bufr = TRUE`
#' @importFrom utils read.fwf
#' @return Returns two lists with values described at: weather.uwyo.edu ; The first list contains:
#' \enumerate{
#'  \item PRES - Pressure (hPa)
#'  \item HGHT - Height (metres)
#'  \item TEMP - Temperature (C)
#'  \item DWPT - Dew point (C)
#'  \item RELH - Relative humidity (%)
#'  \item MIXR - Mixing ratio (g/kg)
#'  \item DRCT - Wind direction (deg)
#'  \item SKNT - Wind speed (knots)
#'  \item THTA = (K)
#'  \item THTE = (K)
#'  \item THTV = (K)
#'  }
#'  The second list contains metadata and calculated thermodynamic / atmospheric instability indices (for TEMP soundings only)
#'
#' @return A list of 2 data.frames where first data frame represents parameters of upper parts o with columns describing the meteorogical parameters (e.g. temperature, air pressure) where each row represent a measurement,
#' depending on the height. Second data.frame presents a description of the conditions under which the sounding was carried out. 
#'
#' @source http://weather.uwyo.edu/upperair/sounding.html
#' @export
#'
#' @examples 
#' \donttest{
#' ##############################################################################
#' # download data for Station 45004 starting 1120Z 11 Jul 2021; Kowloon, HONG KONG, CHINA
#' # using TEMP and BUFR sounding formats
#' ##############################################################################
#' TEMP = sounding_wyoming(wmo_id = 45004, yy = 2021, mm = 07, dd = 17, hh = 12, min = 00)
#' head(TEMP[[1]])
#' BUFR = sounding_wyoming(wmo_id = 45004, yy = 2021, mm = 07, dd = 17, hh = 12, min = 00, bufr = TRUE)
#' head(BUFR[[1]])
#' 
#' 
#' ##############################################################################
#' ### example with a random date to download sounding from LEBA, PL station: ###
#' ##############################################################################
#' 
#'   profile = sounding_wyoming(wmo_id = 12120, 
#'                              yy = sample(2000:2019,1),
#'                              mm = sample(1:12,1), 
#'                              dd = sample(1:20,1), 
#'                              hh = 0)
#'   head(profile)
#'   plot(profile[[1]]$HGHT, profile[[1]]$PRES, type = 'l')
#' }
#'

sounding_wyoming = function(wmo_id, 
                            yy, mm, dd, hh, min = 00, 
                            bufr = FALSE) {

  if (length(yy)!=1 || length(mm)!=1 || length(dd)!=1 || length(hh)!=1) {
    stop("The function supports downloading data for a given day. Please change arguments yy, mm, dd, hh to single values")
  }
  
  if (length(wmo_id)!=1) {
    stop("The function supports downloading data for one station at the time. Please change the `wmo_id` argument to a single value")
  }
  
  mm = formatC(mm, width = 2, format = "d", flag = "0")
  dd = formatC(dd, width = 2, format = "d", flag = "0")
  hh = formatC(hh, width = 2, format = "d", flag = "0")
  min = formatC(min, width = 2, format = "d", flag = "0")
 
  if (bufr) {
    url = paste0("http://weather.uwyo.edu/cgi-bin/bufrraob.py?datetime=", 
                 yy, "-", mm, "-", dd, "+", hh, ":", min, ":00&id=", wmo_id, "&type=TEXT:LIST")
  } else {
    url = paste0("http://weather.uwyo.edu/cgi-bin/sounding?TYPE=TEXT%3ALIST&YEAR=",
                 yy, "&MONTH=", mm, "&FROM=", dd, hh, "&TO=", dd, hh, "&STNM=", wmo_id)
  }
  
  temp = tempfile()
  test_url(url, temp)
  
  # run only if downloaded file is valid
  df = NULL
  if (!is.na(file.size(temp)) & (file.size(temp) > 800)) { 

    txt = read.fwf(file = temp, widths = 1000)
    sects = grep(pattern = "PRE>", x = txt$V1)
    if (length(sects) == 0) {
      stop("HTTP status was '503 Service Unavailable'. Have you provided a correct station id?
      Please check wmo_id numbers at:
      http://weather.uwyo.edu/upperair/sounding.html")
    }
    
    df = read.fwf(file = temp, skip = sects[1] + 4, widths = rep(7, 11),
                     n = (sects[2] - (sects[1] + 5)))
    
    colnames(df) = c("PRES", "HGHT", "TEMP", "DWPT", "RELH",
                      "MIXR", "DRCT", "SKNT", "THTA", "THTE", "THTV")
    
    if (bufr == FALSE) {
      # the section below is not valid for BUFR decoded data:
      txt = read.fwf(file = temp, skip = sects[2] + 1, widths = 1000,
                     n = (sects[3] - (sects[2] + 2)), stringsAsFactors = FALSE)$V1
      df2 = as.data.frame(matrix(data = unlist(strsplit(txt, split = ": ")), ncol = 2, byrow = TRUE))
      colnames(df2) = c("parameter"," value")
    } else {
      # for bufr data try to read only the most essential metadata
      ind = grep(pattern = "Observations", txt$V1)
      df2 = data.frame(bufr_metadata = gsub("<.*?>", "", txt$V1[ind:(ind+1)]), 
                       stringsAsFactors = FALSE)
      # and convert m/s to knots to stay in alignment with the default format used:
      df$SKNT = round(df$SKNT * 1.9438, 1)
    }
  
    df = list(df, df2)
  
    
  } else { # end of checking file size / problems with internet connection
     cat(paste0("Service not working or wmo_id or date not correct. Check url:\n", url)) 
  }
      
  unlink(temp)

  return(df)
}