Evapotranspiration ET0 Calculator

Calculate reference evapotranspiration (ET0) using FAO Penman-Monteith equation.

  • Inputs:
    • r_n (float): Net radiation at the crop surface (MJ/m²/day)
    • t (float): Mean air temperature (°C)
    • u2 (float): Wind speed at 2 meters height (m/s)
    • es (float): Saturation vapor pressure (kPa)
    • ea (float): Actual vapor pressure (kPa)
    • delta (float): Slope of the saturation vapor pressure curve (kPa/°C)
    • gamma (float): Psychrometric constant (kPa/°C)
    • g (float, optional): Soil heat flux density (MJ/m²/day), default is 0
  • Outputs:
    • Reference evapotranspiration (ET0) in mm/day




Results:

  • Introduction to the Function and Application of this Calculator

The Evapotranspiration ET0 Calculator is an essential tool designed to compute reference evapotranspiration (ET0) using the widely accepted FAO Penman-Monteith equation. This value is a critical metric in hydrology, agriculture, and environmental management, as it estimates the rate at which water is transferred from the land surface to the atmosphere through evaporation and plant transpiration. By leveraging this calculator, users can make informed decisions regarding irrigation scheduling, water resource planning, and crop yield optimization. For a deeper understanding of evapotranspiration and its importance, you can explore resources such as FAO.org, which provides comprehensive information on water management practices.

Whether you’re a researcher, farmer, or environmental engineer, this calculator simplifies the complex process of ET0 calculation by automating mathematical computations. It saves time, enhances accuracy, and ensures users can focus on practical applications instead of manual calculations. To further expand your knowledge on the FAO Penman-Monteith equation, consider visiting this detailed overview on Wikipedia.

  • Explanation of Input Parameters

To ensure precise ET0 calculations, the Evapotranspiration ET0 Calculator requires the following input parameters:

  • r_n: The net radiation at the crop surface, measured in MJ/m²/day. It accounts for the energy available for evapotranspiration.
  • t: The mean air temperature in degrees Celsius (°C), which influences the rate of evaporation.
  • u2: The wind speed at a height of 2 meters, measured in m/s. Wind plays a significant role in determining the rate of water vapor movement.
  • es: The saturation vapor pressure in kPa, representing the atmospheric capacity to hold water vapor at a given temperature.
  • ea: The actual vapor pressure in kPa, which reflects the current amount of water vapor in the air.
  • delta: The slope of the saturation vapor pressure curve in kPa/°C. This parameter helps account for the change in vapor pressure with temperature.
  • gamma: The psychrometric constant in kPa/°C, which incorporates atmospheric pressure and thermal properties of moist air.
  • g (optional): The soil heat flux density in MJ/m²/day. By default, this value is set to zero for simplicity, but it can be modified based on specific scenarios.

For more information on these parameters and their significance, you can visit ScienceDirect's resource on evapotranspiration.

  • Explanation of Output Parameters

The primary output of the Evapotranspiration ET0 Calculator is the reference evapotranspiration (ET0), expressed in millimeters per day (mm/day). This value represents the amount of water that would evaporate and transpire from a hypothetical reference crop under standard conditions. ET0 serves as a benchmark for estimating the water needs of various crops, enabling users to optimize irrigation schedules and conserve water resources effectively.

ET0 is indispensable for understanding crop water requirements and assessing the impact of climate variables on evapotranspiration rates. By using this output, users can determine how much water is needed to maintain healthy crop growth without over-irrigating, which is vital for sustainable agriculture and environmental stewardship.

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