Evapotranspiration (version 1.7)

ET.HargreavesSamani: Hargreaves-Samani Formulation

Description

Implementing the Hargreaves-Samani formulation for estimating reference crop evapotranspiration.

Usage

## S3 method for class 'HargreavesSamani':
ET(data, constants, \dots)

Arguments

data

A list of data in class "HargreavesSamani" which contains the following items (climate variables) required by Hargreaves-Samani formulation: "Tmax", "Tmin"

constants

A list named "constants" consists of constants required for the calculation of Hargreaves-Samani formulation which must contain the following items: "Elev" - ground elevation above mean sea level in m, "lambda" - latent heat of vaporisation = 2.45 M

...

Dummy for generic function, no need to define.

Value

• This function returns a object of class HargreavesSamani. Such objects are list with components:
• ET.Daily
  A zoo object containing daily aggregated estimations of Hargreaves-Samani reference crop evapotranspiration.
• ET.Monthly
  A zoo object containing monthly aggregated estimations of Hargreaves-Samani reference crop evapotranspiration.
• ET.Annual
  A zoo object containing annually aggregated estimations of Hargreaves-Samani reference crop evapotranspiration.
• ET.MonthlyAve
  A zoo object containing monthly averaged estimations of daily Hargreaves-Samani reference crop evapotranspiration.
• ET.AnnualAve
  A zoo object containing annually averaged estimations of daily Hargreaves-Samani reference crop evapotranspiration.
• ET_formulation
  A character string containing the name of the formulation used which equals to "Hargreaves-Samani".
• ET_type
  A character string containing the type of the estimation obtained which is "Reference Crop Evapotranspiration".

Details

This formulation provides a single calculation method with no alternatives available.

References

MCMAHON, T., PEEL, M., LOWE, L., SRIKANTHAN, R. & MCVICAR, T. 2012. Estimating actual, potential, reference crop and pan evaporation using standard meteorological data: a pragmatic synthesis. Hydrology and Earth System Sciences Discussions, 9, 11829-11910. HARGREAVES, G. H. & SAMANI, Z. A. 1985. Reference crop evapotranspiration from ambient air temperature. American Society of Agricultural Engineers.

Examples

# Use processed existing data set from kent Town, Adelaide
data("processeddata")
data("constants")

# Set data class to be "HargreavesSamani" to call function
funname <- "HargreavesSamani" 
class(data) <- funname 

# Call generic function ET(data, ...) with class "HargreavesSamani"
results <- ET(data, constants)