Zhang et al. (2026) Dynamic conversion coefficients improve alpine lake daily evaporation estimation based on multi-evaporator observations

Identification

• Journal: Journal of Hydrology
• Year: 2026
• Date: 2026-03-19
• Authors: Fang Zhang, Xiang Li, Xueqin Zhang, Du Zheng
• DOI: 10.1016/j.jhydrol.2026.135333

Research Groups

• Key Lab of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences
• University of Chinese Academy of Sciences
• Ecological Environment Monitoring and Scientific Research Center, Taihu Basin & East China Sea Ecological Environment Supervision and Administration Bureau, Ministry of Ecology and Environment

Short Summary

This study developed a refined pan conversion method with dynamic coefficients, based on multi-evaporator observations, to estimate daily lake surface evaporation (LSE) for alpine lakes, including ice-covered periods, and quantified the meteorological controls on LSE variability.

Objective

• To estimate daily lake surface evaporation (LSE) using a refined pan conversion method with dynamic conversion coefficients based on multiple-evaporator observations.
• To quantify meteorological controls on daily LSE variability using a random forest regression model.

Study Configuration

• Spatial Scale: Yamzhog Yumco, South Tibet, Tibetan Plateau.
• Temporal Scale: From 2009 to 2023.

Methodology and Data

• Models used: Random forest regression model.
• Data sources: Multiple-evaporator observations (20 cm pan evaporation: E-20cm; E601 pan evaporation: E-E601; 20 m² tank evaporation: E-20m²). Hydrometeorological observations.

Main Results

• Daily LSE can be accurately estimated by multiplying daily E-E601 (or E-20cm) with dynamic E-20m²/E-E601 (or E-20m²/E-20cm) ratios during ice-free (or ice-covered) periods, respectively.
• Daily LSE changes are primarily sensitive to thermal conditions (represented by ΔT), atmospheric evaporative demand (VPD), and radiative forcings (mainly net radiation, Rn, and solar radiation, srad).
• Decreases in radiative forcings (Rn and srad) mainly dominate the decline in LSE at the interannual scale.
• At the seasonal scale, seasonal variability in LSE is governed by distinct physical regimes, transitioning from thermal limitation in winter to atmospheric-evaporative-demand control in spring, moisture-turbulence regulation in summer, and radiative decay in autumn.

Contributions

• Establishes a dynamic conversion-coefficient framework for estimating evaporation from alpine lakes, including during ice-covered periods.
• Demonstrates the dominant roles of thermal conditions, atmospheric evaporative demand, and radiative forcings in regulating lake surface evaporation.
• Informs lake evaporation model parameterization and deepens understandings of lake-air interactions in alpine regions.

Funding

• Not specified in the provided text.

Citation

@article{Zhang2026Dynamic,
  author = {Zhang, Fang and Li, Xiang and Zhang, Xueqin and Zheng, Du},
  title = {Dynamic conversion coefficients improve alpine lake daily evaporation estimation based on multi-evaporator observations},
  journal = {Journal of Hydrology},
  year = {2026},
  doi = {10.1016/j.jhydrol.2026.135333},
  url = {https://doi.org/10.1016/j.jhydrol.2026.135333}
}