R/convert.r

In mkoohafkan/wqptools: Outlier Detection Working Group Toolbox

#' Water Year
#'
#' Get the water year for a particular date.
#'
#' @param x A vector of DateTime values
#' @return An integer vector of water years.
#'
#' @importFrom dplyr if_else
#' @importFrom lubridate month year
#' @export
water_year = function(x) {
  as.integer(if_else(month(x) > 9, year(x) + 1, year(x)))
}

#' EC to PSU
#'
#' Convert from Electrical Conductivity (microsiemens) to to Practical
#' Salinity Units (PSU)
#'
#' @details Conversion follows the equation described in
#'   Wagner, R. J., Boulger Jr, R. W., Oblinger, C. J.,
#'   & Smith, B. A. (2006). Guidelines and standard procedures for
#'   continuous water-quality monitors: station operation, record
#'   computation, and data reporting. No. 1-D3.
#'
#' @param ec Electrical Conductivity, in microsiemens.
#' @return Salinity, in PSU.
#'
#' @export
ec_to_psu <- function(ec) {
  K1 = 0.0120
  K2 = -0.2174
  K3 = 25.3283
  K4 = 13.7714
  K5 = -6.4788
  K6 = 2.5842
  seaEC = 53.087 * 1000
  R = ec / seaEC

  S = K1 + (K2 * R ^ (1 / 2)) + (K3 * R) + (K4 * R ^ (3 / 2)) +
    (K5 * R ^ 2) + (K6 * R ^ (5 / 2))
  return(S)
}