Calculate Temperature from relative humidity and dew point

This function calculates the temperature (°C) from relative humidity (%) and dew point temperature (°C).

Usage

calcTemp(RH, DewP, method = c("Magnus", "Buck"))

Arguments

RH: Relative Humidity (0-100%)
DewP: Td (DP), Dew Point (°Celsius)
method: Calculation method: either "Magnus" or "Buck". Defaults to "Magnus".

Value

Temp, Temperature (°Celsius)

Details

This function supports two methods for temperature calculation:

"Magnus" (default): Uses the August-Roche-Magnus approximation, valid for 0°C < Temp < 60°C and 1% < RH < 100%.
"Buck": Uses the Arden Buck equation with Bögel modification, valid for -30°C < Temp < 60°C and 1% < RH < 100%.

The methods calculate temperature based on vapor pressure and saturation vapour pressure relationships. The Magnus method is chosen as the default because it is more stable when used with the calcDP and calcRH_DP functions.

References

Alduchov, O. A., and R. E. Eskridge, 1996: Improved Magnus' form approximation of saturation vapor pressure. J. Appl. Meteor., 35, 601–609

Buck, A. L., 1981: New Equations for Computing Vapor Pressure and Enhancement Factor. J. Appl. Meteor. Climatol., 20, 1527–1532, https://doi.org/10.1175/1520-0450(1981)020<1527:NEFCVP>2.0.CO;2.

Buck (1996), Buck (1996), Buck Research CR-1A User's Manual, Appendix 1.

https://bmcnoldy.earth.miami.edu/Humidity.html

Examples

# Calculate temperature (Temp) at 50% relative humidity (RH) and dew point 15°C (DewP)
# Using Magnus method
calcTemp(50, 15)
#> [1] 26.24387

# Using Buck method
calcTemp(50, 15, method = "Buck")
#> [1] 26.29922

calcTemp(50, calcDP(20, 50))
#> [1] 20


# mydata file
filepath <- data_file_path("mydata.xlsx")
mydata <- readxl::read_excel(filepath, sheet = "mydata", n_max = 5)

mydata |>
  dplyr::mutate(
    DewPoint = calcDP(Temp, RH),
    Temp_default = calcTemp(RH, DewPoint),
    Temp_Buck = calcTemp(RH, DewPoint))
#> # A tibble: 5 × 8
#>   Site   Sensor Date                 Temp    RH DewPoint Temp_default Temp_Buck
#>   <chr>  <chr>  <dttm>              <dbl> <dbl>    <dbl>        <dbl>     <dbl>
#> 1 London Room 1 2024-01-01 00:00:00  21.8  36.8     6.38         21.8      21.8
#> 2 London Room 1 2024-01-01 00:15:00  21.8  36.7     6.34         21.8      21.8
#> 3 London Room 1 2024-01-01 00:29:59  21.8  36.6     6.30         21.8      21.8
#> 4 London Room 1 2024-01-01 00:44:59  21.7  36.6     6.22         21.7      21.7
#> 5 London Room 1 2024-01-01 00:59:59  21.7  36.5     6.18         21.7      21.7