R/gas_transfer.R

In marelac: Tools for Aquatic Sciences

## -----------------------------------------------------------------------------
## The gas transfer coefficient
## -----------------------------------------------------------------------------

gas_transfer <- function (t = 25, u10 = 1, species = c("He", "Ne", "N2",
        "O2", "Ar", "Kr", "Rn", "CH4", "CO2", "N2O", "CCl2F2", "CCL3F",
        "SF6", "CCl4"),
        method = c("Liss", "Nightingale", "Wanninkhof1", "Wanninkhof2"),
        Schmidt = gas_schmidt(t = t, species = species)) {

  method  <- match.arg(method)
  species <- match.arg(species, several.ok = TRUE)
  
  if (! checkVecLength(list(t, u10)))
    warning("Arguments 't' and 'u10' should have the same length or length 1.")    

  #Schmidt <- gas_schmidt(t = t, species = species)
  S600 <- Schmidt/600  
 
  tr  <- switch(method,
    #Liss = ifelse (u10 < 3.6, 0.17 * u10 * Schmidt ^(-2/3),
    #               ifelse (u10 <= 13, (u10 - 3.4) * 2.8 / sqrt(S600),
    #                                (u10 - 8.4) * 5.9 / sqrt(S600))),
    Liss = {
      #tmp <- matrix(0, dim(Schmidt)[1], dim(Schmidt)[2])
      #colnames(tmp) <- colnames(Schmidt)
      tmp <- Schmidt * 0 # create a matrix with same size and names
      tmp[u10 < 3.6] <-  
        (0.17 * u10 * Schmidt^(-2/3))[u10 < 3.6]
      tmp[(3.6 <= u10) & (u10 <= 13)] <-  
        ((u10 - 3.4) * 2.8 / sqrt(S600))[(3.6 <= u10) & (u10 <= 13)]
      tmp[13 < u10] <-  
        ((u10 - 8.4) * 5.9 / sqrt(S600))[13 < u10]
      tmp
    },
    Nightingale = (0.33 * u10 + 0.222 * u10 * u10) / sqrt(S600),
    Wanninkhof1 = 0.31 * u10^2 * sqrt(S600),
    Wanninkhof2 = 0.0283 * u10^3 / sqrt(S600)
  )
  tr/100/3600
}