Hargreaves Potential Evapotranspiration

Description

Hargreaves Potential Evapotranspiration uses a simpler methodology than the Penman-Montieth model used by the American Society of Civil Engineers (ASCE) to estimate potential evapotranspiration. Where the Penman-Montieth model requires temperature, relative humidity, wind, saturation vapor pressure, and net radiation variables, the Hargreaves model requires only temperature and incident radiation. Thus, the Hargreaves model can be used to estimate potential evapotranspiration for a wider range of datasets, including the global ERA5 and ERA5 Ag datasets.

Hargreaves Potential Evapotranspiration is then used by Climate Engine to calculate several additional downstream drought and water balance variables, including the potential water deficit, standardized precipitation evapotranspiration index (SPEI), and the evaporative demand drought index (EDDI).

References

• Hargreaves, G. H., & Samani, Z. A. (1982). Estimating potential evapotranspiration. Journal of the irrigation and Drainage Division, 108(3), 225-230.