ET_penman function

Calculation of daily potential evapotranspiration by Penman (1948) method

This function calculates the potential evapotranspiration (ETref) using daily weather data and the Penman (1948) method

ET_penman(climdata, lat, elev)

Arguments

• climdata: a dataframe with daily weather data. Must contain the columns Year, Month, Day, Tmax, Tmin, RHmax, RHmin, Rad, u2med.
• lat: the latitude of the site, in decimal degrees.
• elev: the elevation of the site, in meters above sea level.

Returns

dataframe where Date, DOY and ET columns have been added to the ones in climadata data frame.

Details

This version of the function requires the user to supply in weather data daily values for temperature (Tmax and Tmin), relative humidity (RHmax and RHmin), solar radiation (Rad in MJ m-2 day-1) and mean wind speed at 2m height (u2med in m s-1).

Examples

# Calculate ET by Penman method in the Tudela_DW example dataset
data(Tudela_DW)
library(magrittr)
library(dplyr)
elevation <- 314
latitude <- 42.13132
ET_Penman <- ET_penman(Tudela_DW, elevation, latitude)

References

Penman HL 1948.Natural evaporation from open water, bare soil and grass. Proc. R. Soc. Lond. 193:120–145.

Author(s)

Carlos Miranda, carlos.miranda@unavarra.es