Assessment of Multi-Source Evapotranspiration Products over China Using Eddy Covariance Observations

Li, Shijie; Wang, Guojie; Sun, Shilei; Chen, Haishan; Bai, Peng; Zhou, Shujia; Huang, Yong; Wang, Jie; Deng, Peng

doi:10.3390/rs10111692

Cited by 34 publications

(26 citation statements)

References 142 publications

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“…(Wei et al, 2017). Other observational studies suggest that annual T / ET averages nearly 2/3 globally (0.61 ± 0.15, Schlesinger and Jasechko, 2014;0.64 ± 0.13, Good et al, 2015; and 0.66 ± 0.13 across some FLUXNET sites, Li et al, 2019). Intercomparison studies agree on the large uncertainty surrounding these estimates, with reported global terrestrial annual T / ET ratios ranging from 0.35 to 0.90 (Coenders-Gerrits et al, 2014;Fatichi and Pappas, 2017;Young-Robertson et al, 2018).…”

Section: Vegetation Plays a Central Role In Evaporation And Transpiramentioning

confidence: 90%

“…The ratio of transpiration to evapotranspiration (T / ET) at annual timescales is related to aridity (Good et al, 2017) but appears to be relatively insensitive to annual precipitation (P ) (Schlesinger and Jasechko, 2014). T / ET is sensitive to ecosystem characteristics, namely the leaf area index (LAI) Fatichi and Pappas, 2017;Wang et al, 2014;Wei et al, 2015), especially on sub-annual timescales (Li et al, 2019;Scott and Biederman, 2017), noting that LAI is related to P at longer timescales. A higher LAI favors T and E from intercepted water (E i ) at the expense of E from soil (E soil ) such that LAI explains some 43 % of the variability of annual T / ET across global ecosystems .…”

Section: Vegetation Plays a Central Role In Evaporation And Transpiramentioning

confidence: 99%

“…A modified (in this case binned) parameter optimization approach was used by Li et al (2019) to estimate g surf , which follows the model proposed by Lin et al (2018):…”

Section: Partitioning Et Using Half-hourly Eddy Covariance Observationsmentioning

confidence: 99%

“…The Perez-Priego et al (2018) and Li et al (2019) methods both circumvent the assumption that T / ET approaches unity at some periods by estimating ecosystem conductances directly. The transpiration estimation algorithm (TEA) from Nelson et al (2018) utilizes a nonparametric model and thereby further limits assumptions made about how the ecosystem functions.…”

Section: Partitioning Et Using Half-hourly Eddy Covariance Observationsmentioning

confidence: 99%

“…(b) The distribution of the best-fit exponential parameter (m) for 240 sites in the La Thuile FLUXNET database that contained the full energy balance measurements and ecosystem type information used in Stoy et al (2013). less than 0.2 m 3 m −3 , and that E scaled with time −0.5 following Brutsaert (2014) (see also Boese et al, 2019, andLi et al, 2019). 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 .…”

Section: Does T / Et Approach Unity?mentioning

confidence: 99%

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

et al. 2019

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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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Section: Vegetation Plays a Central Role In Evaporation And Transpiramentioning

confidence: 90%

Section: Vegetation Plays a Central Role In Evaporation And Transpiramentioning

confidence: 99%

“…A modified (in this case binned) parameter optimization approach was used by Li et al (2019) to estimate g surf , which follows the model proposed by Lin et al (2018):…”

Section: Partitioning Et Using Half-hourly Eddy Covariance Observationsmentioning

confidence: 99%

Section: Partitioning Et Using Half-hourly Eddy Covariance Observationsmentioning

confidence: 99%

Section: Does T / Et Approach Unity?mentioning

confidence: 99%

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

et al. 2019

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Multimodel‐based analyses of evapotranspiration and its controls in China over the last three decades

et al. 2020

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Evapotranspiration (ET) plays a key role in linking water, energy, and carbon cycles. However, at regional scales, variations and controls of ET are still not well understood, due to the substantial uncertainties in ET estimates. Here, the variations in ET over China during the last three decades and their drivers and controls were analysed at monthly, seasonal, and annual scales, using well‐evaluated land surface model simulations. The results suggested that (a) the spatially averaged ET over China increased during 1979–2012 at each temporal scale. Overall, the ET significantly increased (p < .05) in most of western China and decreased in several regions in eastern China during most months and seasons. (a) The increases in spatially averaged ET during the nongrowing season were mainly determined by warming. The increased annual ET, seasonal ET, and monthly ET within the growing season were jointly caused by vegetation greening and climate warming. (c) During November–March, ET was primarily determined by temperature in most of central China and was determined by water availability in the remaining regions. The annual ET and the monthly ET within April–October were mainly controlled by water availability in most of northern and western China, and several regions in central China, by solar radiation in most of central and southern China and by temperature in some regions in the Tibetan Plateau. The study highlights the large effects of warming and greening on ET over China during the last three decades. The results may benefit water resource management under climate change.

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Spatiotemporal shifts in key hydrological variables and dominant factors over China

Sun

Zhou

et al. 2021

Hydrological Processes

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Quantitatively and physically understanding changes in land surface hydrology is a hot topic in the hydro-meteorological research, especially over China with high population density but uneven distribution of water resources. Therefore, the spatiotemporal dynamics (i.e., the 1980s [1981-1990] and 1990s [1991-2000] relative to the baseline of [1961][1962][1963][1964][1965][1966][1967][1968][1969][1970][1971][1972][1973][1974][1975][1976][1977][1978][1979][1980] in evapotranspiration (ET) and streamflow/runoff (Q) were examined across 426 hydrological divisions (HDs) of China. Both the 1980s and 1990s ET decreased over roughly 50% HDs mainly in the central and southeast parts of China, while the 1980s (1990s) Q decreased over slightly higher than 50% (63%) HDs generally in north and southwest China (the central and north parts of China).Relative to the 1980s, more HDs had strong changes in ET and Q in 1990s. Based on the separated contributions of precipitation (P), reference ET and Budyko-type equation parameter n (an integrated variable of catchment property) to ET and Q changes, we found that in 1980s and 1990s, n dominated ET changes over about 60% HDs mainly in the south, with the dominant of P around 35% HDs generally in the north and northeast, while for Q changes, nearly 60% (slightly less than 40%) HDs were dominated by n (P). Moreover, the dominants for ET (Q) changes have shifted from 1980s to 1990s over 36% (45%) HDs, mainly changing from P to n. This study provides a framework for quantitatively understanding land surface hydrological dynamics from the perspectives of climatic and physiographic controls over regions.

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Assessment of Multi-Source Evapotranspiration Products over China Using Eddy Covariance Observations

Cited by 34 publications

References 142 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

Multimodel‐based analyses of evapotranspiration and its controls in China over the last three decades

Spatiotemporal shifts in key hydrological variables and dominant factors over China

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