Simulate Evapotranspiration

Simulates reference evapotranspiration (ET0) using temperature, relative humidity, solar radiation, and wind speed.

simulate_evapotranspiration(
  temperature,
  rh,
  solar_radiation,
  wind_speed,
  method = "FAO56",
  crop_factor = 1,
  humidity_sensitivity = 0.35,
  wind_sensitivity = 0.08,
  radiation_sensitivity = 0.12,
  noise_sd = 0.25,
  min_et = 0,
  max_et = 15,
  seed = NULL
)

Arguments

temperature

Output from simulate_temperature().

rh

Output from simulate_rh().

solar_radiation

Output from simulate_solar_radiation().

wind_speed

Output from simulate_wind_speed().

method

Method used for evapotranspiration estimation. Currently supports:

FAO56

Simplified FAO-56 Penman-Monteith inspired approach

Default is "FAO56".

crop_factor

Numeric scaling factor for evapotranspiration. Default is 1.

humidity_sensitivity

Numeric humidity reduction factor. Default is 0.35.

wind_sensitivity

Numeric aerodynamic enhancement factor. Default is 0.08.

radiation_sensitivity

Numeric solar radiation enhancement factor. Default is 0.12.

noise_sd

Standard deviation for stochastic variability. Default is 0.25.

min_et

Minimum ET0 value. Default is 0.

max_et

Maximum ET0 value. Default is 15.

seed

Optional random seed.

Value

A data frame containing:

Station

Station identifier

LON

Longitude

LAT

Latitude

ELEV

Elevation (m)

DATE

Date

Year

Year

Month

Month

Season

Season category

Avg.Temp

Average temperature (°C)

RH

Relative humidity (%)

Solar_Radiation

Solar radiation (MJ/m²/day)

WindSpeed

Wind speed (m/s)

Atmospheric_Pressure

Estimated atmospheric pressure (kPa)

VPD

Vapour pressure deficit (kPa)

ET0

Reference evapotranspiration (mm/day)

Dryness_Index

Normalized dryness indicator

Dryness_Class

Categorical atmospheric moisture condition derived from the dryness index.Classes include: Humid, Moderate, Dry, and Very Dry

ET_Anomaly

Evapotranspiration anomaly

Details

The function incorporates:

• temperature-driven evaporation

• humidity suppression

• solar radiation forcing

• aerodynamic wind enhancement

• elevation-based pressure adjustment

• stochastic environmental variability

Examples

if (FALSE) { # \dontrun{
temp <- simulate_temperature(stations, tindex_month)
rh   <- simulate_rh(stations, tindex_month)
sr   <- simulate_solar_radiation(stations, tindex_month)
ws   <- simulate_wind_speed(stations, tindex_month)

et <- simulate_evapotranspiration(
  temperature = temp,
  rh = rh,
  solar_radiation = sr,
  wind_speed = ws
)
} # }