Moro et al. (2026) Proposal for using daily thermal amplitude to estimate reference evapotranspiration without relative humidity

Identification

• Journal: Journal of Hydrology
• Year: 2026
• Date: 2026-09-27
• Authors: Iulo Pessotti Moro, Sidney Sára Zanetti, Roberto Avelino Cecílio, José Eduardo Macedo Pezzopane
• DOI: 10.1016/j.jhydrol.2026.136484

Research Groups

• Universidade Federal do Espírito Santo, Centro de Ciências Agrárias e Engenharias, Departamento de Ciências Florestais e da Madeira

Short Summary

This study proposes a new method to estimate dew point temperature (Tdew) using minimum temperature (Tmin) and daily thermal amplitude (TA), aiming to calculate actual vapor pressure (ea) and reference evapotranspiration (ETo) in data-limited scenarios.

Objective

• Estimate Tdew as a function of Tmin and TA, allowing for more accurate calculation of ea and ETo.

Study Configuration

• Spatial Scale: Brazil-wide, with 584 automatic weather stations across different climates.
• Temporal Scale: Daily meteorological data from 2000 to 2025.

Methodology and Data

• Models used: Penman-Monteith method (ETo PM) and a new method proposed in this study.
• Data sources: Daily meteorological data from automatic weather stations, including maximum and minimum air temperature, relative humidity, global solar radiation, and wind speed.

Main Results

• The new method estimates Tdew by subtracting 0.2 times the daily thermal amplitude (TA) from Tmin, resulting in more accurate calculations of ea and ETo.
• The proposed model outperforms traditional methods in most Brazilian climates, with a median MAE of 0.11 mm day−1 and a median RMSE of 0.15 mm day−1.

Contributions

• This study provides a physically consistent and easily applicable alternative for estimating ETo in regions without relative air humidity data.
• The proposed method eliminates the subjectivity of arbitrary correction factors, making it more robust and adaptable to different climates.

Funding

• Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) (ROR identifier: 00x0ma614).

Citation

@article{Moro2026Proposal,
  author = {Moro, Iulo Pessotti and Zanetti, Sidney Sára and Cecílio, Roberto Avelino and Pezzopane, José Eduardo Macedo},
  title = {Proposal for using daily thermal amplitude to estimate reference evapotranspiration without relative humidity},
  journal = {Journal of Hydrology},
  year = {2026},
  doi = {10.1016/j.jhydrol.2026.136484},
  url = {https://doi.org/10.1016/j.jhydrol.2026.136484}
}