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Title: Land surface models systematically overestimate the intensity, duration and magnitude of seasonal-scale evaporative droughts

Land surface models (LSMs) must accurately simulate observed energy and water fluxes during droughts in order to provide reliable estimates of future water resources. We evaluated 8 different LSMs (14 model versions) for simulating evapotranspiration (ET) during periods of evaporative drought (Edrought) across six flux tower sites. Using an empirically defined Edrought threshold (a decline in ET below the observed 15th percentile), we show that LSMs simulated 58 Edrought days per year, on average, across the six sites, ~3 times as many as the observed 20 d. The simulated Edrought magnitude was ~8 times greater than observed and twice as intense. Our findings point to systematic biases across LSMs when simulating water and energy fluxes under water-stressed conditions. The overestimation of key Edrought characteristics undermines our confidence in the models' capability in simulating realistic drought responses to climate change and has wider implications for phenomena sensitive to soil moisture, including heat waves.
Authors:
ORCiD logo [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [1] ;  [1]
  1. Univ. of New South Wales, Sydney, NSW (Australia). ARC Centre of Excellence for Climate System Science
  2. Macquarie Univ., NSW (Australia). Dept. of Biological Sciences
  3. Univ. of New South Wales, Sydney, NSW (Australia). ARC Centre of Excellence for Climate System Science; Univ. of New South Wales, Sydney, NSW (Australia). Climate Change Research Centre
  4. Met Office, Devon (United Kingdom)
  5. Univ. of New South Wales, Sydney, NSW (Australia). ARC Centre of Excellence for Climate System Science; Univ. of New South Wales, Sydney, NSW (Australia). Climate Change Research Centre
  6. Commonwealth Scientific and Industrial Research Organization (CSIRO), Canberra, ACT (Australia). Oceans and Atmosphere (O&A)
Publication Date:
Grant/Contract Number:
FG02-04ER63917; FG02-04ER63911
Type:
Accepted Manuscript
Journal Name:
Environmental Research Letters
Additional Journal Information:
Journal Volume: 11; Journal Issue: 10; Journal ID: ISSN 1748-9326
Publisher:
IOP Publishing
Research Org:
Oregon State Univ., Corvallis, OR (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); Australian Research Council (ARC)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; land surface models; evaporative drought; evapotranspiration; heat waves; FLUXNET
OSTI Identifier:
1361497