R/calculate_altitude.R

In KiranLDA/PAMLr: Suite Of Functions For Manipulating Pressure, Activity, Magnetism, Temperature And Light Data In R

#' Calculate altitude from pressure
#'
#' @description  This function calculates altitude from atmospheric pressure
#'
#' @param P on-bird pressure in hectopascals
#' @param P0 pressure at sea level in hectopascals
#' @param T0 temperature at sea level in kelvin (i.e. celcius + 273.15 OR (Farenheit - 32) * 5/9 + 273.15)
#'
#' @return altitude in metres calculated according to International Standard Atmosphere model (International Organization for Standardization 1975: ISO 2533:1975)
#' @references Atmosphere, S., 1975. International organization for standardization. ISO, 2533, p.1975.
#'
#' @examples
#' altitude = calculate_altitude(P = hoopoe$pressure$obs)
#' plot(hoopoe$pressure$date,
#'      altitude,
#'      type="o",
#'      pch=16,
#'      xlab="Date",
#'      ylab="Altitude (m)")
#'
#' @export
calculate_altitude <- function( P,
                          T0 = 288.15,
                          P0 = 1013.25) {
  L = -0.0065
  altitude = -(T0 / L)*(1-((P/P0)^(1/5.2561)))
  return(altitude)
}