Lei et al. (2026) Investigating the aerodynamic and radiation components of the Penman equation for water surface evaporation estimation

Identification

• Journal: Agricultural Water Management
• Year: 2026
• Date: 2026-06-29
• Authors: Xin Lei, Ke-Wu Han, Ke-bin Shi, Xinjun Yan, Shaolei Wang
• DOI: 10.1016/j.agwat.2026.110580

Research Groups

• College of Hydraulic and Civil Engineering, Xinjiang Agricultural University
• Xinjiang Key Laboratory of Hydraulic Engineering Security and Water Disasters Prevention

Short Summary

This study improves the classical Penman model by using water surface temperature instead of air temperature to calculate saturation vapor pressure and introducing a Bowen ratio correction factor. The results indicate that the modified model performs best when heat storage flux is included, with an RMSE of 0.99 mm d⁻¹.

Objective

• Investigate the influence of using air temperature versus water temperature in saturation vapor pressure calculations on the accuracy of evaporation estimation.
• Develop an error compensation mechanism for the Penman model based on the physical response relationship of the Bowen ratio, introduce a correction coefficient (1 + β), and establish an improved evaporation model.

Study Configuration

• Spatial Scale: Local scale, with field experiments conducted at the Heigou Watershed Soil and Water Conservation Reservoir in Xinjiang.
• Temporal Scale: Monthly timescale, with data collected from March to October 2018.

Methodology and Data

• Models used: Modified Penman equation (Eq. 15) incorporating the (1 + β) correction factor.
• Data sources: Field measurements of meteorological variables, including air temperature, water temperature, relative humidity, wind speed, shortwave radiation, and evaporation.

Main Results

• The modified model using water surface temperature to calculate saturation vapor pressure and incorporating the Bowen ratio correction factor performs best when heat storage flux is included (RMSE = 0.99 mm d⁻¹).
• The inclusion of heat storage flux reduces the average error by 17.8% compared to neglecting it.
• The Bowen ratio-based correction factor enhances energy partitioning, reducing bias in latent heat flux estimates.

Contributions

• This study provides a methodological improvement for water surface evaporation estimation, enhancing accuracy and supporting refined water resources management.
• The results provide a scientific basis for understanding the influence of temperature differences at the water-air interface on energy partitioning.

Funding

• This research was funded by the National Natural Science Foundation of China (Grant No. 51879223) and the Xinjiang Uygur Autonomous Region Science and Technology Plan Project (Grant No. 2021AB01101).

Citation

@article{Lei2026Investigating,
  author = {Lei, Xin and Han, Ke-Wu and Shi, Ke-bin and Yan, Xinjun and Wang, Shaolei},
  title = {Investigating the aerodynamic and radiation components of the Penman equation for water surface evaporation estimation},
  journal = {Agricultural Water Management},
  year = {2026},
  doi = {10.1016/j.agwat.2026.110580},
  url = {https://doi.org/10.1016/j.agwat.2026.110580}
}