• PENMAN will calculate potential evapotranspiration by the Penman method (Ponce, V. M., 1989. Engineering Hydrology, Principles and Practices, Prentice Hall). The Dunne formula is used to calculate the mass-transfer evaporation rate.

  • The input data is [mean monthly] temperature (degrees Celsius), the given month, and [mean monthly] net radiation (cal/cm2/day). Relative humidity (%), and wind velocity at 2-m depth (km/day), required by the Dunne formula, are also required as input.

  • The output data is daily PET (cm) and monthly PET (cm).

  • Allowable input data ranges:   Temperature is restricted in the range 0-40 degree Celsius; [mean monthly] net radiation in the range 0-1200 cal/cm2/day; humidity in the range 0-100%; wind velocity at 2-m depth in the range 0-800 km/day. Input values outside of these ranges will cause the respective value to reset to the closest limit [Example: entering 1000 for wind velocity will cause its value to reset to 800].

Click  -here- to view a sample data set.

RUN!

DISCLAIMER: The developer makes no warranties, expressed or implied, concerning the accuracy, completeness, reliability, or suitability of this program for any one particular purpose. It is understood that the user proceeds at his/her own risk.