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photo of Zheng Duan on Lund webpage

Zheng Duan

Senior lecturer

photo of Zheng Duan on Lund webpage

Land Surface Energy Partitioning Dominates Dry-Season Water Availability Uncertainties in Earth System Models

Author

  • Jianzhi Dong
  • Man Gao
  • Jianhong Zhou
  • Lingna Wei
  • Haoran Zhou
  • Yongqiang Zhang
  • Hongkai Gao
  • Zheng Duan
  • Wade T. Crow

Summary, in English

Accurately characterizing dry-season water availability (Wd) is critical for projecting terrestrial carbon exchange and global water security. Wd is commonly calculated as the minimum value of precipitation minus evapotranspiration within each calendar year. However, Earth System Model (ESM) projected Wd contains substantial uncertainties and can disagree on even the sign. Based on a newly proposed framework, we disentangle the uncertainty sources in ESM-based Wd projections. Results demonstrate that ESM-based Wd uncertainties are dominated by land surface energy partitioning (summarized by evaporation fraction, denoted as EF) instead of precipitation or available energy. As such, EF alone can explain more than 83% of inter-ESM variability in historical and future Wd projections. Compared against data-driven benchmarks, ESMs tend to overestimate dry-season EF—suggesting that Wd is likely to be underestimated in ESMs. Our analysis indicates that the ET resistance parameterization is the central error source in ESM-based EF, which should be constrained to enhance the reliability of EF, and by extension, Wd projections.

Department/s

  • Dept of Physical Geography and Ecosystem Science
  • BECC: Biodiversity and Ecosystem services in a Changing Climate
  • MERGE: ModElling the Regional and Global Earth system

Publishing year

2025-05

Language

English

Publication/Series

Water Resources Research

Volume

61

Issue

5

Document type

Journal article

Publisher

Wiley-Blackwell

Topic

  • Oceanography, Hydrology and Water Resources
  • Water Engineering
  • Climate Science

Keywords

  • earth system modeling
  • evaporation fraction
  • evapotranspiration
  • uncertainty
  • water availability

Status

Published

ISBN/ISSN/Other

  • ISSN: 0043-1397