ET.Penman {Evapotranspiration} | R Documentation |

Implementing the Penman formulation for estimating open-water evaporation or potential evapotranspiration

## S3 method for class 'Penman' ET(data, constants, ts="daily", solar="sunshine hours", wind="yes", windfunction_ver=1948, alpha=0.08, z0=0.001, message="yes", AdditionalStats="yes", save.csv="no", ...)

`data` |
A list which contains the following items (climate variables) required by Penman formulation: |

`constants` |
A list named |

`ts` |
Must be either |

`solar` |
Must be either |

`wind` |
Must be either |

`windfunction_ver` |
The version of Penman wind function that will be used within the Penman formulation. Must be either |

`alpha` |
Any numeric value between 0 and 1 (dimensionless), albedo of evaporative surface representing the portion of the incident radiation that is reflected back at the surface. |

`z0` |
Any value (metres), roughness height of the evaporative surface. |

`message` |
Must be either |

`AdditionalStats` |
"yes" or "no" indicating whether monthly averaged and annual averaged ET should be calculated. |

`save.csv` |
Must be either |

`...` |
Dummy for generic function, no need to define. |

The alternative calculation options can be selected through arguments `solar`

, `wind`

and `windfunction_ver`

, please see `Arguments`

for details.

User-defined evaporative surface is allowed through arguments `alpha`

and `z0`

, please see `Arguments`

for details.

The function generates a list containing the following components:

`ET.Daily` |
Daily aggregated estimations of Penman open-water evaporation or potential evapotranspiration. |

`ET.Monthly` |
Monthly aggregated estimations of Penman open-water evaporation or potential evapotranspiration. |

`ET.Annual` |
Annually aggregated estimations of Penman open-water evaporation or potential evapotranspiration. |

`ET.MonthlyAve` |
Monthly averaged estimations of daily Penman open-water evaporation or potential evapotranspiration. |

`ET.AnnualAve` |
Annually averaged estimations of daily Penman open-water evaporation or potential evapotranspiration. |

`ET_formulation` |
Name of the formulation used which equals to |

`ET_type` |
Type of the estimation obtained which is either |

`message1` |
A message to inform the users about how solar radiation has been calculated by using which data. |

`message2` |
A message to inform the users about if actual wind data has been used in the calculations or alternative calculations has been performed without wind data, and which version of the Penman wind function has been used. |

Danlu Guo

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.

Penman, H. L. 1948. *Natural evaporation from open water, bare soil and grass*. Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences, 193, 120-145.

Valiantzas, J. D. 2006. *Simplified versions for the Penman evaporation equation using routine weather data*. Journal of Hydrology, 331, 690-702.

Penman, H. L. 1956. *Evaporation: An introductory survey*. Netherlands Journal of Agricultural Science, 4, 9-29.

`ET`

,`processeddata`

,`defaultconstants`

,`constants`

# Use processed existing data set and constants from # kent Town, Adelaide data("processeddata") data("constants") # Call ET.Penman under the generic function ET results <- ET.Penman(processeddata, constants, ts="daily", solar="sunshine hours", wind="yes", windfunction_ver = "1948", alpha = 0.08, z0 = 0.001, message="yes", AdditionalStats="yes", save.csv="no")

[Package *Evapotranspiration* version 1.15 Index]