Evapotranspiration (version 1.7)

ET.Abtew: Abtew Formulation

Description

Implementing the Abtew formulation for estimating actual evapotranspiration.

Usage

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

Arguments

data

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

constants

A list named "constants" consists of constants required for the calculation of Abtew 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 "data", "sunshine hours", "cloud" or "monthly precipitation". "data" indicates that solar radiation is to be used directly for calculating evapotranspiration; "sunshine hours" indicates that solar radiation is to be calculated using the rea

...

Dummy for generic function, no need to define.

Value

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

ABTEW, W. 1996. EVAPOTRANSPIRATION MEASUREMENTS AND MODELING FOR THREE WETLAND SYSTEMS IN SOUTH FLORIDA1. Wiley Online Library.

Examples

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

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

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