Partitioning global land evapotranspiration using CMIP5 models constrained by observations

Xu Lian; Shilong Piao; Chris Huntingford; Yue Li; Zhenzhong Zeng; Xuhui Wang; Philippe Ciais; Tim Mcvicar; Shushi Peng; Catherine Ottle; Hui Yang; Yuting Yang; Yongqiang Zhang; Tao Wang

Partitioning global land evapotranspiration using CMIP5 models constrained by observations

Xu Lian ¹ Shilong Piao ^{1, 2} Chris Huntingford ³ Yue Li ¹ Zhenzhong Zeng ¹ Xuhui Wang ² Philippe Ciais ⁴ Tim Mcvicar ⁵ Shushi Peng ¹ Catherine Ottle ⁴ Hui Yang ¹ Yuting Yang ⁶ Yongqiang Zhang ⁵ Tao Wang ⁷

1 Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences

2 Key Laboratory of Alpine Ecology and Biodiversity

3 CEH - Centre for Ecology and Hydrology [Wallingford]

4 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]

5 CSIRO - Commonwealth Scientific and Industrial Research Organisation [Canberra]

6 State Key Laboratory of Hydroscience and Engineering & Department of Hydraulic Engineering

7 CAS Center for Excellence in Tibetan Plateau Earth Sciences

Abstract : The ratio of plant transpiration to total terrestrial evapotranspiration (T/ET) captures the role of vegetation in surface–atmosphere interactions. However, its magnitude remains highly uncertain at the global scale. Here we apply an emergent constraint approach that integrates CMIP5 Earth system models (ESMs) with 33 field T/ET measurements to re-estimate the global T/ET value. Our observational constraint strongly increases the original ESM estimates (0.41 ± 0.11) and greatly alleviates intermodel discrepancy, which leads to a new global T/ET estimate of 0.62 ± 0.06. For all the ESMs, the leaf area index is identified as the primary driver of spatial variations of T/ET, but to correct its bias generates a larger T/ET underestimation than the original ESM output. We present evidence that the ESM underestimation of T/ET is, instead, attributable to inaccurate representation of canopy light use, interception loss and root water uptake processes in the ESMs. These processes should be prioritized to reduce model uncertainties in the global hydrological cycle.

Document type :

Journal articles

Domain :

Environmental Sciences

Complete list of metadatas

https://hal-cea.archives-ouvertes.fr/cea-01874286
Contributor : Bruno Savelli <>
Submitted on : Friday, September 14, 2018 - 11:22:41 AM
Last modification on : Saturday, February 16, 2019 - 5:12:01 PM

Partitioning global land evapotranspiration using CMIP5 models constrained by observations

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Partitioning global land evapotranspiration using CMIP5 models constrained by observations

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