Evapotranspiration (version 1.7)

ET.Makkink: Makkink Formulation

Description

Implementing the Makkink formulation for estimating potential evaporation.

Usage

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

Arguments

data

A list of data in class "Makkink" which contains the following items (climate variables) required by Makkink formulation: "Tmax", "Tmin", "Rs", "n" or "Cd"

constants

A list named "constants" consists of constants required for the calculation of Makkink formulation which must contain the following items: "Elev" - ground elevation above mean sea level in m, "lambda" - latent heat of vaporisation = 2.45 MJ.kg^-1,

solar

Must be either "sunshine hours", "data", "cloud" or "monthly precipitation". "sunshine hours" indicates that solar radiation data will be used directly for calculating evapotranspiration; "data" indicates that solar radiation is to be calculated using the

...

Dummy for generic function, no need to define.

Value

• This function returns a object of class Makkink. Such objects are list with components:
• ET.Daily
  A zoo object containing daily aggregated estimations of Makkink potential evaporation.
• ET.Monthly
  A zoo object containing monthly aggregated estimations of Makkink potential evaporation.
• ET.Annual
  A zoo object containing annually aggregated estimations of Makkink potential evaporation.
• ET.MonthlyAve
  A zoo object containing monthly averaged estimations of daily Makkink potential evaporation.
• ET.AnnualAve
  A zoo object containing annually averaged estimations of daily Makkink potential evaporation.
• ET_formulation
  A character string containing the name of the formulation used which equals to "Makkink".
• ET_type
  A character string containing the type of the estimation obtained which is "Potential Evaporation".
• message1
  A message to inform the users about how solar radiation has been calculated by using which data.

Details

The alternative calculation options can be selected through argument solar, please see "Arguments" for details.

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.

Examples

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

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

# Call generic function ET(data, ...) with class "Makkink"
results <- ET(data, constants, solar="sunshine hours")