Evapotranspiration seasonality across the Amazon Basin

Maeda, EE; Ma, X; Wagner, FH; Kim, H; Oki, T; Eamus, D; Huete, A

Evapotranspiration seasonality across the Amazon Basin

Maeda, EE

Ma, X

Wagner, FH Kim, H Oki, T Eamus, D

Huete, A

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Publication Type:: Journal Article
Citation:: Earth System Dynamics, 2017, 8 (2), pp. 439 - 454
Issue Date:: 2017-06-30

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Field	Value	Language
dc.contributor.author	Maeda, EE https://orcid.org/0000-0001-7932-1824	en_US
dc.contributor.author	Ma, X https://orcid.org/0000-0003-1499-8476	en_US
dc.contributor.author	Wagner, FH	en_US
dc.contributor.author	Kim, H	en_US
dc.contributor.author	Oki, T	en_US
dc.contributor.author	Eamus, D https://orcid.org/0000-0003-2765-8040	en_US
dc.contributor.author	Huete, A https://orcid.org/0000-0003-2809-2376	en_US
dc.date.issued	2017-06-30	en_US
dc.identifier.citation	Earth System Dynamics, 2017, 8 (2), pp. 439 - 454	en_US
dc.identifier.issn	2190-4979	en_US
dc.identifier.uri	http://hdl.handle.net/10453/123813
dc.description.abstract	© 2017 Author(s). Evapotranspiration (ET) of Amazon forests is a main driver of regional climate patterns and an important indicator of ecosystem functioning. Despite its importance, the seasonal variability of ET over Amazon forests, and its relationship with environmental drivers, is still poorly understood. In this study, we carry out a water balance approach to analyse seasonal patterns in ET and their relationships with water and energy drivers over five sub-basins across the Amazon Basin. We used in situ measurements of river discharge, and remotely sensed estimates of terrestrial water storage, rainfall, and solar radiation. We show that the characteristics of ET seasonality in all sub-basins differ in timing and magnitude. The highest mean annual ET was found in the northern Rio Negro basin (∼ 1497 mm year-1) and the lowest values in the Solimões River basin (∼ 986 mm year-1). For the first time in a basin-scale study, using observational data, we show that factors limiting ET vary across climatic gradients in the Amazon, confirming local-scale eddy covariance studies. Both annual mean and seasonality in ET are driven by a combination of energy and water availability, as neither rainfall nor radiation alone could explain patterns in ET. In southern basins, despite seasonal rainfall deficits, deep root water uptake allows increasing rates of ET during the dry season, when radiation is usually higher than in the wet season. We demonstrate contrasting ET seasonality with satellite greenness across Amazon forests, with strong asynchronous relationships in ever-wet watersheds, and positive correlations observed in seasonally dry watersheds. Finally, we compared our results with estimates obtained by two ET models, and we conclude that neither of the two tested models could provide a consistent representation of ET seasonal patterns across the Amazon.	en_US
dc.relation	http://purl.org/au-research/grants/arc/DP140102698
dc.relation.ispartof	Earth System Dynamics	en_US
dc.relation.isbasedon	10.5194/esd-8-439-2017	en_US
dc.title	Evapotranspiration seasonality across the Amazon Basin	en_US
dc.type	Journal Article
utslib.citation.volume	2	en_US
utslib.citation.volume	8	en_US
utslib.for	0406 Physical Geography and Environmental Geoscience	en_US
utslib.for	0401 Atmospheric Sciences	en_US
utslib.for	0405 Oceanography	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Faculty of Science/School of Life Sciences
pubs.organisational-group	/University of Technology Sydney/Strength - CAMGIS - Centre for Advanced Modelling and Geospatial lnformation Systems
utslib.copyright.status	open_access
pubs.issue	2	en_US
pubs.publication-status	Published	en_US
pubs.volume	8	en_US

Abstract:

© 2017 Author(s). Evapotranspiration (ET) of Amazon forests is a main driver of regional climate patterns and an important indicator of ecosystem functioning. Despite its importance, the seasonal variability of ET over Amazon forests, and its relationship with environmental drivers, is still poorly understood. In this study, we carry out a water balance approach to analyse seasonal patterns in ET and their relationships with water and energy drivers over five sub-basins across the Amazon Basin. We used in situ measurements of river discharge, and remotely sensed estimates of terrestrial water storage, rainfall, and solar radiation. We show that the characteristics of ET seasonality in all sub-basins differ in timing and magnitude. The highest mean annual ET was found in the northern Rio Negro basin (∼ 1497 mm year-1) and the lowest values in the Solimões River basin (∼ 986 mm year-1). For the first time in a basin-scale study, using observational data, we show that factors limiting ET vary across climatic gradients in the Amazon, confirming local-scale eddy covariance studies. Both annual mean and seasonality in ET are driven by a combination of energy and water availability, as neither rainfall nor radiation alone could explain patterns in ET. In southern basins, despite seasonal rainfall deficits, deep root water uptake allows increasing rates of ET during the dry season, when radiation is usually higher than in the wet season. We demonstrate contrasting ET seasonality with satellite greenness across Amazon forests, with strong asynchronous relationships in ever-wet watersheds, and positive correlations observed in seasonally dry watersheds. Finally, we compared our results with estimates obtained by two ET models, and we conclude that neither of the two tested models could provide a consistent representation of ET seasonal patterns across the Amazon.

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http://hdl.handle.net/10453/115036