Title: Improving Representation of Deforestation Effects on Evapotranspiration in the E3SM Land Model

Abstract

Evapotranspiration (ET) plays an important role in land-atmosphere coupling of energy, water, and carbon cycles. Following deforestation, ET is typically observed to decrease substantially as a consequence of decreases in leaf area and roots and increases in runoff. Changes in ET (latent heat flux) revise the surface energy and water budgets, which further affects large-scale atmospheric dynamics and feeds back positively or negatively to long-term forest sustainability. In this study, we used observations from a recent synthesis of 29 pairs of adjacent intact and deforested FLUXNET sites to improve model parameterization of stomatal characteristics, photosynthesis, and soil water dynamics in version 1 of the Energy Exascale Earth System Model (E3SM) Land Model (ELMv1). We found that default ELMv1 predicts an increase in ET after deforestation, likely leading to incorrect estimates of the effects of deforestation on land-atmosphere coupling. The calibrated model accurately represented the FLUXNET observed deforestation effects on ET. Importantly, the search for global optimal parameters converged at values consistent with recent observational syntheses, confirming the reliability of the calibrated physical parameters. Applying this improved model parameterization to the globe scale reduced the bias of annual ET simulation by up to ~600 mm/year. Analysis on the roles of parametersmore » suggested that future model development to improve ET simulation should focus on stomatal resistance and soil water-related parameterizations. Finally, our predicted differences in seasonal ET changes from deforestation are large enough to substantially affect land-atmosphere coupling and should be considered in such studies.« less

Authors:

Cai, Xitian  ^[1];

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Riley, William J.  ^[1];

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Zhu, Qing  ^[1];

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Tang, Jinyun  ^[1];

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Zeng, Zhenzhong  ^[2];

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Bisht, Gautam  ^[1];

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Randerson, James T.  ^[3]

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+ Show Author Affiliations

1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
2. Southern Univ. of Science and Technology, Shenzhen (China); Princeton Univ., NJ (United States)
3. Univ. of California, Irvine, CA (United States)

Publication Date:

2019-07-02

Research Org.:

Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)

OSTI Identifier:

1567946

Alternate Identifier(s):

OSTI ID: 1567948; OSTI ID: 1572832

Grant/Contract Number:  

AC02-05CH11231; DE‐AC02‐05CH11231

Resource Type:

Published Article

Journal Name:

Journal of Advances in Modeling Earth Systems

Additional Journal Information:

Journal Volume: 11; Journal Issue: 8; Journal ID: ISSN 1942-2466

Publisher:

American Geophysical Union (AGU)

Country of Publication:

United States

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES; deforestation; evapotranspiration; Earth system model; land use and land cover; E3SM; climate effects