Partitioning evapotranspiration of a drip-irrigated wheat crop: Inter-comparing eddy covariance-, sap flow-, lysimeter- and FAO-based methods

Rafi, Zoubair; Merlin, Olivier; Dantec, Valérie Le; Khabba, Saïd; Mordelet, Patrick; Er‐Raki, Salah; Amazirh, Abdelhakim; Olivera-Guerra, Luis; Hssaine, Bouchra Ait; Simonneaux, Vincent; Ezzahar, Jamal; Ferrer, Francesc

doi:10.1016/j.agrformet.2018.11.031

Cited by 72 publications

(46 citation statements)

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“…These findings of a sustained evaporation component and non-zero E/ET even during dry conditions were also supported by lysimeter measurements in a semiarid grassland (Moran et al, 2009) and partly confirmed by a recent study based on isotopes on shrubs and steppe ecosystem . The maximum daily T/ET found by Scanlon and Kustas (2012) in a maize agroecosystem was also about 0.8, but Rana et al (2018) found daily values that intermittently exceeded 0.9 in wheat and fava bean fields and multi-method comparisons suggest that T/ET 10 approaches 0.85 (Rafi et al, 2019). Anderson et al (2017a) found that T/ET routinely exceeded 0.9 in sugarcane, with maximum daily values above 0.95.…”

Section: Does T/et Approach Unity?mentioning

confidence: 96%

Reviews and syntheses: Turning the challenges of partitioning ecosystem evaporation and transpiration into opportunities

Stoy¹,

El‐Madany²,

Fisher³

et al. 2019

Preprint

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Evaporation (E) and transpiration (T) respond differently to ongoing changes in climate, atmospheric composition, and land use. Our ability to partition evapotranspiration (ET) into E and T is limited at the ecosystem scale, which renders the validation of satellite data and land surface models incomplete. Here, we review current progress in partitioning E and T, and provide a prospectus for how to improve theory and observations going forward. Recent advancements in analytical techniques provide additional opportunities for partitioning E and T at the ecosystem scale, but their assumptions have yet to be fully 35 tested. Many approaches to partition E and T rely on the notion that plant canopy conductance and ecosystem water use efficiency (EWUE) exhibit optimal responses to atmospheric vapor pressure deficit (D). We use observations from 240 eddy covariance flux towers to demonstrate that optimal ecosystem response to D is a reasonable assumption, in agreement with recent studies, but the conditions under which this assumption holds require further analysis. Another critical assumption for many ET partitioning approaches is that ET can be approximated as T during ideal transpiring conditions, which has been 40 Biogeosciences Discuss., https://doi.

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Section: Does T/et Approach Unity?mentioning

confidence: 96%

Reviews and syntheses: Turning the challenges of partitioning ecosystem evaporation and transpiration into opportunities

Stoy¹,

El‐Madany²,

Fisher³

et al. 2019

Preprint

View full text Add to dashboard Cite

show abstract

“…These findings of a sustained evaporation component and nonzero E/ET even during dry conditions were also supported by lysimeter measurements in a semiarid grassland (Moran et al, 2009) and partly confirmed by a recent study based on isotopes in shrubs and a steppe ecosystem . The maximum daily T / ET found by Scanlon and Kustas (2012) in a maize agroecosystem was also about 0.8, but Rana et al (2018) found daily values that intermittently exceeded 0.9 in wheat and fava bean fields, and multi-method comparisons suggest that T / ET often approaches 0.85 (Rafi et al, 2019). Anderson et al (2017a) found that T / ET routinely exceeded 0.9 in sugarcane, with maximum daily values above 0.95, and Li et al (2019) also found values greater than 0.9 for other crops.…”

Section: Does T / Et Approach Unity?mentioning

confidence: 97%

Reviews and syntheses: Turning the challenges of partitioning ecosystem evaporation and transpiration into opportunities

et al. 2019

View full text Add to dashboard Cite

Evaporation (E) and transpiration (T ) respond differently to ongoing changes in climate, atmospheric composition, and land use. It is difficult to partition ecosystem-scale evapotranspiration (ET) measurements into E and T , which makes it difficult to validate satellite data and land surface models. Here, we review current progress in partitioning E and T and provide a prospectus for how to improve theory and observations going forward. Recent advancements in analytical techniques create new opportunities for partitioning E and T at the ecosystem scale, but their assumptions have yet to be fully tested. For example, many approaches to partition E and T rely on the notion that plant canopy conductance and ecosystem water use efficiency exhibit optimal responses to atmospheric vapor pressure deficit (D). We use observations from 240 eddy covariance flux towers to demonstrate that optimal ecosystem response to D is a reasonable assumption, in agreement with recent studies, but more analysis is necessary to determine the conditions for which this assumption holds. Another critical assumption for many partitioning approaches is that ET can be approximated as T during ideal transpiring conditions, which has been challenged by observational studies. We demonstrate that T can exceed 95 % of ET from certain ecosystems, but other ecosystems do not appear to reach this value, which suggests that this assumption is ecosystem-dependent with implications for partitioning. It is important to further improve approaches for partitioning E and T , yet few multi-method comparisons have been undertaken to date. Advances in our understanding of carbon-water coupling at the stomatal, leaf, and canopy level open new perspectives on how to quantify T via its strong coupling with photosynthesis. Photosynthesis can be constrained at the ecosystem and global scales with emerging data sources including solar-induced fluorescence, carbonyl sulfide flux measurements, thermography, and more. Such comparisons would improve our mechanistic understanding of ecosystem water fluxes and provide the observations necessary to validate remote sensing algorithms and land surface models to understand the changing global water cycle.

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“…As a consequence, the spatial modeling has become a dominant means of estimating ET fluxes over regional and continental areas (Anderson et al, 2007;Fisher et al, 2017). In this context, numerous models based on land surface temperature (LST) data have been developed, such as (i) residual balance methods that consider ET to be the residual term of the energy balance, like TSEB (two-source energy balance, and SEBS (surface energy balance system, Su, 2002), (ii) contextual methods that estimate ET as the potential ET times the evaporative efficiency (Moran et al, 1994) or as the available energy times the evaporative fraction (Merlin et al, 2013;Roerink et al, 2000) and (iii) other categories of models that integrate LST into a water balance model or into the Penman-Monteith energy balance (PMEB) equation to directly estimate ET Mallick et al, 2015Mallick et al, , 2018.…”

Section: Introductionmentioning

confidence: 99%

An evapotranspiration model self-calibrated from remotely sensed surface soil moisture, land surface temperature and vegetation cover fraction: application to disaggregated SMOS and MODIS data

Hssaine

Merlin

Ezzahar

et al. 2020

Hydrol. Earth Syst. Sci.

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Abstract. Thermal-based two-source energy balance modeling is essential to estimate the land evapotranspiration (ET) in a wide range of spatial and temporal scales. However, the use of thermal-derived land surface temperature (LST) is not sufficient to simultaneously constrain both soil and vegetation flux components. Therefore, assumptions (about either soil or vegetation fluxes) are commonly required. To avoid such assumptions, an energy balance model, TSEB-SM, was recently developed by Ait Hssaine et al. (2018b) in order to consider the microwave-derived near-surface soil moisture (SM), in addition to the thermal-derived LST and vegetation cover fraction (fc) normally used. While TSEB-SM has been successfully tested using in situ measurements, this paper represents its first evaluation in real life using 1 km resolution satellite data, comprised of MODIS (MODerate resolution Imaging Spectroradiometer) for LST and fc data and 1 km resolution SM data disaggregated from SMOS (Soil Moisture and Ocean Salinity) observations. The approach is applied during a 4-year period (2014–2018) over a rainfed wheat field in the Tensift basin, central Morocco. The field used was seeded for the 2014–2015 (S1), 2016–2017 (S2) and 2017–2018 (S3) agricultural seasons, while it remained unploughed (as bare soil) during the 2015–2016 (B1) agricultural season. The classical TSEB model, which is driven only by LST and fc data, significantly overestimates latent heat fluxes (LE) and underestimates sensible heat fluxes (H) for the four seasons. The overall mean bias values are 119, 94, 128 and 181 W m−2 for LE and −104, −71, −128 and −181 W m−2 for H, for S1, S2, S3 and B1, respectively. Meanwhile, when using TSEB-SM (SM and LST combined data), these errors are significantly reduced, resulting in mean bias values estimated as 39, 4, 7 and 62 W m−2 for LE and −10, 24, 7, and −59 W m−2 for H, for S1, S2, S3 and B1, respectively. Consequently, this finding confirms again the robustness of the TSEB-SM in estimating latent/sensible heat fluxes at a large scale by using readily available satellite data. In addition, the TSEB-SM approach has the original feature to allow for calibration of its main parameters (soil resistance and Priestley–Taylor coefficient) from satellite data uniquely, without relying either on in situ measurements or on a priori parameter values.

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Partitioning evapotranspiration of a drip-irrigated wheat crop: Inter-comparing eddy covariance-, sap flow-, lysimeter- and FAO-based methods

Cited by 72 publications

References 50 publications

Reviews and syntheses: Turning the challenges of partitioning ecosystem evaporation and transpiration into opportunities

Reviews and syntheses: Turning the challenges of partitioning ecosystem evaporation and transpiration into opportunities

Reviews and syntheses: Turning the challenges of partitioning ecosystem evaporation and transpiration into opportunities

An evapotranspiration model self-calibrated from remotely sensed surface soil moisture, land surface temperature and vegetation cover fraction: application to disaggregated SMOS and MODIS data

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