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Title: A novel approach to partitioning evapotranspiration into evaporation and transpiration in flooded ecosystems

Journal Article · · Global Change Biology
DOI:https://doi.org/10.1111/gcb.15974· OSTI ID:1982911

Abstract Reliable partitioning of micrometeorologically measured evapotranspiration (ET) into evaporation ( E ) and transpiration ( T ) would greatly enhance our understanding of the water cycle and its response to climate change related shifts in local‐to‐regional climate conditions and rising global levels of vapor pressure deficit (VPD). While some methods on ET partitioning have been developed, their underlying assumptions make them difficult to apply more generally, especially in sites with large contributions of E . Here, we report a novel ET partitioning method using artificial neural networks (ANNs) in combination with a range of environmental input variables to predict daytime E from nighttime ET measurements. The study uses eddy covariance data from four restored wetlands in the Sacramento‐San Joaquin Delta, California, USA, as well as leaf‐level T data for validation. The four wetlands vary in their vegetation make‐up and structure, representing a range of ET conditions. The ANNs were built with increasing complexity by adding the input variable that resulted in the next highest average value of model testing R 2 across all sites. The order of variable inclusion (and importance) was: VPD > gap‐filled sensible heat flux ( H _gf) > air temperature ( T air ) > friction velocity ( u ) > other variables. The model using VPD, H _gf, T air , and u showed the best performance during validation with independent data and had a mean testing R 2  value of 0.853 (averaged across all sites, range from 0.728 to 0.910). In comparison to other methods, our ANN method generated T /ET partitioning results which were more consistent with CO 2 exchange data especially for more heterogeneous sites with large E contributions. Our method improves the understanding of T /ET partitioning. While it may be particularly suited to flooded ecosystems, it can also improve T /ET partitioning in other systems, increasing our knowledge of the global water cycle and ecosystem functioning.

Research Organization:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). AmeriFlux
Sponsoring Organization:
USDOE Office of Science (SC); USDA
Grant/Contract Number:
AC02-05CH11231; 2011-67003-30371; 7079856)
OSTI ID:
1982911
Alternate ID(s):
OSTI ID: 1830275
Journal Information:
Global Change Biology, Vol. 28, Issue 3; ISSN 1354-1013
Publisher:
WileyCopyright Statement
Country of Publication:
United States
Language:
English

References (67)

A simple and objective method to partition evapotranspiration into transpiration and evaporation at eddy-covariance sites journal February 2019
A Hybrid Model for Mapping Relative Differences in Belowground Biomass and Root: Shoot Ratios Using Spectral Reflectance, Foliar N and Plant Biophysical Data within Coastal Marsh journal December 2015
Assessing the eddy covariance technique for evaluating carbon dioxide exchange rates of ecosystems: past, present and future journal April 2003
The increasing importance of atmospheric demand for ecosystem water and carbon fluxes journal September 2016
Comprehensive comparison of gap-filling techniques for eddy covariance net carbon fluxes journal December 2007
Earth's Global Energy Budget journal March 2009
Scaling Properties of Biologically Active Scalar Concentration Fluctuations in the Atmospheric Surface Layer over a Managed Peatland journal June 2010
Closing the Water Cycle from Observations across Scales: Where Do We Stand? journal October 2021
Nocturnal evapotranspiration in eddy-covariance records from three co-located ecosystems in the Southeastern U.S.: Implications for annual fluxes journal September 2009
Assessing the carbon and climate benefit of restoring degraded agricultural peat soils to managed wetlands journal April 2019
Recent decline in the global land evapotranspiration trend due to limited moisture supply journal October 2010
Correction of flux measurements for density effects due to heat and water vapour transfer journal January 1980
Fluxpart: Open source software for partitioning carbon dioxide and water vapor fluxes journal May 2018
Nighttime transpiration in woody plants from contrasting ecosystems journal April 2007
Impact of Earth Greening on the Terrestrial Water Cycle journal April 2018
Systemic effects of rising atmospheric vapor pressure deficit on plant physiology and productivity journal March 2021
Energy balance closure at FLUXNET sites journal December 2002
A review of models and micrometeorological methods used to estimate wetland evapotranspiration journal July 2004
Historic and projected changes in vapor pressure deficit suggest a continental‐scale drying of the United States atmosphere journal February 2017
A 10 per cent increase in global land evapotranspiration from 2003 to 2019 journal May 2021
Productive wetlands restored for carbon sequestration quickly become net CO2 sinks with site-level factors driving uptake variability journal March 2021
A comparison of methods for determining forest evapotranspiration and its components: sap-flow, soil water budget, eddy covariance and catchment water balance journal January 2001
Coupling Water and Carbon Fluxes to Constrain Estimates of Transpiration: The TEA Algorithm journal December 2018
On the separation of net ecosystem exchange into assimilation and ecosystem respiration: review and improved algorithm journal September 2005
Subsidence of Agricultural Lands in the Sacramento-San Joaquin Delta, California: Role of Aqueous and Gaseous Carbon Fluxes journal August 1996
The control of stomata by water balance: Tansley review journal August 2005
Soil moisture dominates dryness stress on ecosystem production globally journal September 2020
On the correlation structure of water vapor and carbon dioxide in the atmospheric surface layer: A basis for flux partitioning: CORRELATION OF WATER VAPOR AND CARBON DIOXIDE journal October 2008
Agricultural peatland restoration: effects of land-use change on greenhouse gas (CO 2 and CH 4 ) fluxes in the Sacramento-San Joaquin Delta journal October 2014
Gap‐filling approaches for eddy covariance methane fluxes: A comparison of three machine learning algorithms and a traditional method with principal component analysis journal October 2019
Reviews and syntheses: Turning the challenges of partitioning ecosystem evaporation and transpiration into opportunities journal January 2019
No growth stimulation of tropical trees by 150 years of CO2 fertilization but water-use efficiency increased journal December 2014
Climatology, Variability, and Trends in the U.S. Vapor Pressure Deficit, an Important Fire-Related Meteorological Quantity journal June 2015
Increased atmospheric vapor pressure deficit reduces global vegetation growth journal August 2019
A new assessment of European forests carbon exchanges by eddy fluxes and artificial neural network spatialization journal April 2003
Assessing the potential functions of nocturnal stomatal conductance in C 3 and C 4 plants journal May 2019
Hydrologic cycle explains the evaporation paradox journal November 1998
On the Use of the Term “Evapotranspiration” journal October 2020
Partitioning evapotranspiration using long-term carbon dioxide and water vapor fluxes: New Approach to ET Partitioning journal July 2017
A Unique Combination of Aerodynamic and Surface Properties Contribute to Surface Cooling in Restored Wetlands of the Sacramento‐San Joaquin Delta, California journal July 2018
Global Hydrological Cycles and World Water Resources journal August 2006
Canopy Leaf Area Index in Non-Forested Marshes of the California Delta journal May 2016
Tools for quality assessment of surface-based flux measurements journal January 1996
Surface Moistening Trends in the Northern North American Great Plains Increase the Likelihood of Convective Initiation journal January 2018
Measuring Biosphere-Atmosphere Exchanges of Biologically Related Gases with Micrometeorological Methods journal October 1988
Factors that control Typha marsh evapotranspiration journal February 2007
Partitioning carbon dioxide and water vapor fluxes using correlation analysis journal January 2010
Empirical assessment of uncertainties of meteorological parameters and turbulent fluxes in the AmeriFlux network: UNCERTAINTIES IN THE AMERIFLUX NETWORK journal December 2012
Nighttime Stomatal Conductance and Transpiration in C 3 and C 4 Plants journal January 2007
On the separation of net ecosystem exchange into assimilation and ecosystem respiration: review and improved algorithm journal September 2005
Cross-site evaluation of eddy covariance GPP and RE decomposition techniques journal June 2008
Partitioning net carbon dioxide fluxes into photosynthesis and respiration using neural networks journal July 2020
Inter-annual variability in the leaf area index of a boreal aspen-hazelnut forest in relation to net ecosystem production journal November 2004
The effect of land cover type and structure on evapotranspiration from agricultural and wetland sites in the Sacramento–San Joaquin River Delta, California journal June 2018
Plant responses to rising vapor pressure deficit journal March 2020
The FLUXCOM ensemble of global land-atmosphere energy fluxes journal May 2019
Effect of Drought-Induced Salinization on Wetland Methane Emissions, Gross Ecosystem Productivity, and Their Interactions journal August 2019
Transpiration in the global water cycle journal June 2014
Gap-filling eddy covariance methane fluxes: Comparison of machine learning model predictions and uncertainties at FLUXNET-CH4 wetlands journal October 2021
Biophysical controls on interannual variability in ecosystem-scale CO 2 and CH 4 exchange in a California rice paddy : INTERANNUAL VARIABILITY RICE CH journal March 2016
Revisiting the partitioning of net ecosystem exchange of CO2 into photosynthesis and respiration with simultaneous flux measurements of 13CO2 and CO2, soil respiration and a biophysical model, CANVEG journal March 2017
Partitioning evapotranspiration based on the concept of underlying water use efficiency: ET PARTITIONING journal February 2016
Physics‐Constrained Machine Learning of Evapotranspiration journal December 2019
Global patterns of land-atmosphere fluxes of carbon dioxide, latent heat, and sensible heat derived from eddy covariance, satellite, and meteorological observations journal January 2011
AmeriFlux US-Myb Mayberry Wetland dataset January 2010
AmeriFlux US-Tw1 Twitchell Wetland West Pond dataset January 2012
AmeriFlux US-Sne Sherman Island Restored Wetland dataset January 2016