# R/getSchmidt.R In LakeMetabolizer: Tools for the Analysis of Ecosystem Metabolism

#### Documented in getSchmidt

#'@title Returns Schmidt number for a specific gas at a given temperature
#'@description
#'Schmidt number is temperature dependant, and is the ratio of the kinematic viscosity of water
#'to a diffusion coefficient. Coefficients are included for He, O2, CO2, CH4, SF6, N2O, Ar, and N2.\cr
#'
#'@usage
#'getSchmidt(temperature, gas)
#'
#'@param temperature Numeric vector of water temperatures in deg. Celsius
#'@param gas String for gas code. Valid inputs include: He, O2, CO2, CH4, SF6, N2O, Ar, and N2
#'@return Schmidt number (unitless)
#'@note Temperature range is only valid from 4-35 deg Celsius
#'@keywords methods math
#'@references
#'Raymond, Peter A., Christopher J. Zappa, David Butman, Thomas L. Bott, Jody Potter, Patrick Mulholland,
#'Andrew E. Laursen, William H. McDowell, and Denis Newbold. \emph{Scaling the gas transfer velocity and hydraulic
#'geometry in streams and small rivers}. Limnology & Oceanography: Fluids & Environments 2 (2012): 41-53.
#'@author
#'@examples
#'getSchmidt(temperature=12, gas="O2")
#'@export
getSchmidt	<-	function(temperature, gas){

range.t	<-	c(4,35) # supported temperature range

Schmidt	<-	data.frame(
"He"=c(368,-16.75,0.374,-0.0036),
"O2"=c(1568,-86.04,2.142,-0.0216),
"CO2"=c(1742,-91.24,2.208,-0.0219),
"CH4"=c(1824,-98.12,2.413,-0.0241),
"SF6"=c(3255,-217.13,6.837,-0.0861),
"N2O"=c(2105,-130.08,3.486,-0.0365),
"Ar"=c(1799,-106.96,2.797,-0.0289),
"N2"=c(1615,-92.15,2.349,-0.0240)
)

obsT <- is.finite(temperature) # logical for observed (not NA or NaN [or Inf or -Inf]) -RDB

if (!is.character(gas)){stop(paste('gas must be a character. was given as',gas))}
if (length(gas)>1){stop("only one gas can be specified for this version")}
if (any(temperature[obsT] < range.t[1] | temperature[obsT] > range.t[2])){ # This logical threw an error if any temperature were NA (or NaN, etc.) -RDB
warning("temperature out of range")
}
A	<-	unlist(Schmidt[gas])[1]
B	<-	unlist(Schmidt[gas])[2]
C	<-	unlist(Schmidt[gas])[3]
D	<-	unlist(Schmidt[gas])[4]

Sc = as.numeric(A+B*temperature+C*temperature^2+D*temperature^3)

return(Sc)
}


## Try the LakeMetabolizer package in your browser

Any scripts or data that you put into this service are public.

LakeMetabolizer documentation built on Nov. 16, 2022, 1:09 a.m.