Partitioning evapotranspiration using long‐term carbon dioxide and water vapor fluxes

Abstract The separate components of evapotranspiration (ET) elucidate the pathways and time scales over which water is returned to the atmosphere, but ecosystem‐scale measurements of transpiration (T) and evaporation (E) remain elusive. We propose a novel determination of E and T using multiyear edd...

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Main Authors: Russell L. Scott, Joel A. Biederman
Format: Article
Language:English
Published: Wiley 2017-07-01
Series:Geophysical Research Letters
Subjects:
Online Access:https://doi.org/10.1002/2017GL074324
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author Russell L. Scott
Joel A. Biederman
author_facet Russell L. Scott
Joel A. Biederman
author_sort Russell L. Scott
collection DOAJ
description Abstract The separate components of evapotranspiration (ET) elucidate the pathways and time scales over which water is returned to the atmosphere, but ecosystem‐scale measurements of transpiration (T) and evaporation (E) remain elusive. We propose a novel determination of E and T using multiyear eddy covariance estimates of ET and gross ecosystem photosynthesis (GEP). The method is applicable at water‐limited sites over time periods during which a linear regression between GEP (abscissa) and ET (ordinate) yields a positive ET axis intercept, an estimate of E. At four summer‐rainfall semiarid sites, T/ET increases to a peak coincident with maximum GEP and remains elevated as the growing season progresses, consistent with previous, direct measurements. The seasonal course of T/ET is related to increasing leaf area index and declining frequency of rainy days—an index of the wet surface conditions that promote E—suggesting both surface and climatic controls on ET partitioning.
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spelling doaj-art-c4239f78acfb4a6cb7995f47aa0c7b712025-08-20T01:51:46ZengWileyGeophysical Research Letters0094-82761944-80072017-07-0144136833684010.1002/2017GL074324Partitioning evapotranspiration using long‐term carbon dioxide and water vapor fluxesRussell L. Scott0Joel A. Biederman1Southwest Watershed Research Center USDA Agricultural Research Service Tucson Arizona USASouthwest Watershed Research Center USDA Agricultural Research Service Tucson Arizona USAAbstract The separate components of evapotranspiration (ET) elucidate the pathways and time scales over which water is returned to the atmosphere, but ecosystem‐scale measurements of transpiration (T) and evaporation (E) remain elusive. We propose a novel determination of E and T using multiyear eddy covariance estimates of ET and gross ecosystem photosynthesis (GEP). The method is applicable at water‐limited sites over time periods during which a linear regression between GEP (abscissa) and ET (ordinate) yields a positive ET axis intercept, an estimate of E. At four summer‐rainfall semiarid sites, T/ET increases to a peak coincident with maximum GEP and remains elevated as the growing season progresses, consistent with previous, direct measurements. The seasonal course of T/ET is related to increasing leaf area index and declining frequency of rainy days—an index of the wet surface conditions that promote E—suggesting both surface and climatic controls on ET partitioning.https://doi.org/10.1002/2017GL074324evapotranspirationtranspirationevaporationeddy covariancewatercarbon
spellingShingle Russell L. Scott
Joel A. Biederman
Partitioning evapotranspiration using long‐term carbon dioxide and water vapor fluxes
Geophysical Research Letters
evapotranspiration
transpiration
evaporation
eddy covariance
water
carbon
title Partitioning evapotranspiration using long‐term carbon dioxide and water vapor fluxes
title_full Partitioning evapotranspiration using long‐term carbon dioxide and water vapor fluxes
title_fullStr Partitioning evapotranspiration using long‐term carbon dioxide and water vapor fluxes
title_full_unstemmed Partitioning evapotranspiration using long‐term carbon dioxide and water vapor fluxes
title_short Partitioning evapotranspiration using long‐term carbon dioxide and water vapor fluxes
title_sort partitioning evapotranspiration using long term carbon dioxide and water vapor fluxes
topic evapotranspiration
transpiration
evaporation
eddy covariance
water
carbon
url https://doi.org/10.1002/2017GL074324
work_keys_str_mv AT russelllscott partitioningevapotranspirationusinglongtermcarbondioxideandwatervaporfluxes
AT joelabiederman partitioningevapotranspirationusinglongtermcarbondioxideandwatervaporfluxes