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dc.contributor.authorZhou, Sha
dc.contributor.authorYu, Bofu
dc.contributor.authorHuang, Yuefei
dc.contributor.authorWang, Guangqian
dc.date.accessioned2017-05-05T03:46:05Z
dc.date.available2017-05-05T03:46:05Z
dc.date.issued2015
dc.identifier.issn2169-8953
dc.identifier.doi10.1002/2015JG002947
dc.identifier.urihttp://hdl.handle.net/10072/100902
dc.description.abstractWater use efficiency (WUE) is a crucial parameter to describe the interrelationship between gross primary production (GPP) and evapotranspiration (ET). Incorporating the nonlinear effect of vapor pressure deficit (VPD), underlying WUE (uWUE = GPP · VPD0.5/ET) is better than inherent WUE (IWUE = GPP · VPD/ET) at the half-hourly time scale. However, appropriateness of uWUE has not yet been evaluated at the daily time scale. To determine whether uWUE is better than IWUE, daily data for seven vegetation types from 34 AmeriFlux sites were used to validate uWUE at the daily time scale. First, daily mean VPD was shown to be a good substitute for the effective VPD that was required to preserve daily GPP totals. Second, an optimal exponent, k*, corresponding to the best linear relationship between GPP · VPDk* and ET, was about 0.55 both at half-hourly and daily time scales. Third, correlation coefficient between GPP · VPDk and ET showed that uWUE (k = 0.5 and r = 0.85) was a better approximation of the optimal WUE (k = k* and r = 0.86) than IWUE (k = 1 and r = 0.81) at the daily scale. Finally, when yearly uWUE was used to predict daily GPP from daily ET and mean VPD, uWUE worked considerably better than IWUE. Comparing observed and predicted daily GPP, the average correlation coefficient and Nash-Sutcliffe coefficient of efficiency were 0.81 and 0.59, respectively, using yearly uWUE, and only 0.59 and −0.83 using yearly IWUE. As a nearly optimal WUE, uWUE consistently outperformed IWUE and could be used to evaluate the effects of global warming and elevated atmosphere CO2 on carbon assimilation and evapotranspiration.
dc.description.peerreviewedYes
dc.languageEnglish
dc.language.isoeng
dc.publisherJohn Wiley & Sons
dc.relation.ispartofpagefrom887
dc.relation.ispartofpageto902
dc.relation.ispartofissue5
dc.relation.ispartofjournalJournal of Geophysical Research: Biogeosciences
dc.relation.ispartofvolume120
dc.subject.fieldofresearchPhysical Geography and Environmental Geoscience not elsewhere classified
dc.subject.fieldofresearchGeophysics
dc.subject.fieldofresearchcode040699
dc.subject.fieldofresearchcode0404
dc.titleDaily underlying water use efficiency for AmeriFlux sites
dc.typeJournal article
dc.type.descriptionC1 - Articles
dc.type.codeC - Journal Articles
dcterms.licensehttp://creativecommons.org/licenses/by-nc-nd/4.0/
dc.description.versionVersion of Record (VoR)
gro.rights.copyright© 2015. The Authors.This is an open access article under theterms of the Creative CommonsAttribution-NonCommercial-NoDerivsLicense, which permits use and distri-bution in any medium, provided theoriginal work is properly cited, the use isnon-commercial and no modi?cationsor adaptations are made.
gro.hasfulltextFull Text
gro.griffith.authorYu, Bofu


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