The GEWEX LandFlux project: evaluation of model evaporation using tower-based and globally-gridded forcing data

Handle URI:
http://hdl.handle.net/10754/576052
Title:
The GEWEX LandFlux project: evaluation of model evaporation using tower-based and globally-gridded forcing data
Authors:
McCabe, Matthew ( 0000-0002-1279-5272 ) ; Ershadi, Ali ( 0000-0002-8885-1947 ) ; Jimenez, C.; Miralles, D. G. ( 0000-0001-6186-5751 ) ; Michel, D.; Wood, E. F.
Abstract:
Determining the spatial distribution and temporal development of evaporation at regional and global scales is required to improve our understanding of the coupled water and energy cycles and to better monitor any changes in observed trends and variability of linked hydrological processes. With recent international efforts guiding the development of long-term and globally distributed flux estimates, continued product assessments are required to inform upon the selection of suitable model structures and also to establish the appropriateness of these multi-model simulations for global application. In support of the objectives of the GEWEX LandFlux project, four commonly used evaporation models are evaluated against data from tower-based eddy-covariance observations, distributed across a range of biomes and climate zones. The selected schemes include the Surface Energy Balance System (SEBS) approach, the Priestley-Taylor Jet Propulsion Laboratory (PT-JPL) model, the Penman-Monteith based Mu model (PM-Mu) and the Global Land Evaporation: the Amsterdam Methodology (GLEAM). Here we seek to examine the fidelity of global evaporation simulations by examining the multi-model response to varying sources of forcing data. To do this, we perform parallel and collocated model simulations using tower-based data together with a global-scale grid-based forcing product. Through quantifying the multi-model response to high-quality tower data, a better understanding of the subsequent model response to coarse-scale globally gridded data that underlies the LandFlux product can be obtained, while also providing a relative evaluation and assessment of model performance. <br><br> Using surface flux observations from forty-five globally distributed eddy-covariance stations as independent metrics of performance, the tower-based analysis indicated that PT-JPL provided the highest overally statistical performance (0.72; 61 W m<sup>−2</sup>; 0.65), followed closely by GLEAM (0.68; 64 W m<sup>−2</sup>; 0.62), with values in parenthesis representing the <i>R</i><sup>2</sup>, RMSD and Nash-Sutcliffe Efficiency (NSE) and respectively. PM-Mu (0.51; 78 W m<sup>−2</sup>; 0.45) tended to underestimate fluxes, while SEBS (0.72; 101 W m<sup>−2</sup>; 0.24) overestimated values relative to observations. A focused analysis across specific biome types and climate zones showed considerable variability in the performance of all models, with no single model consistently able to outperform any other. Results also indicated that the global gridded data tended to reduce the performance for all of the studied models when compared to the tower data, likely a response to scale mismatch and issues related to forcing quality. Rather than relying on any single model simulation, the spatial and temporal variability at both the tower- and grid-scale highlighted the potential benefits of developing an ensemble or blended evaporation product for global scale LandFlux applications. Challenges related to the robust assessment of the LandFlux product are also discussed.
KAUST Department:
Biological and Environmental Sciences and Engineering (BESE) Division
Citation:
The GEWEX LandFlux project: evaluation of model evaporation using tower-based and globally-gridded forcing data 2015, 8 (8):6809 Geoscientific Model Development Discussions
Publisher:
Copernicus GmbH
Journal:
Geoscientific Model Development Discussions
Issue Date:
24-Aug-2015
DOI:
10.5194/gmdd-8-6809-2015
Type:
Article
ISSN:
1991-962X
Additional Links:
http://www.geosci-model-dev-discuss.net/8/6809/2015/
Appears in Collections:
Articles; Biological and Environmental Sciences and Engineering (BESE) Division; Biological and Environmental Sciences and Engineering (BESE) Division

Full metadata record

DC FieldValue Language
dc.contributor.authorMcCabe, Matthewen
dc.contributor.authorErshadi, Alien
dc.contributor.authorJimenez, C.en
dc.contributor.authorMiralles, D. G.en
dc.contributor.authorMichel, D.en
dc.contributor.authorWood, E. F.en
dc.date.accessioned2015-08-30T11:20:19Zen
dc.date.available2015-08-30T11:20:19Zen
dc.date.issued2015-08-24en
dc.identifier.citationThe GEWEX LandFlux project: evaluation of model evaporation using tower-based and globally-gridded forcing data 2015, 8 (8):6809 Geoscientific Model Development Discussionsen
dc.identifier.issn1991-962Xen
dc.identifier.doi10.5194/gmdd-8-6809-2015en
dc.identifier.urihttp://hdl.handle.net/10754/576052en
dc.description.abstractDetermining the spatial distribution and temporal development of evaporation at regional and global scales is required to improve our understanding of the coupled water and energy cycles and to better monitor any changes in observed trends and variability of linked hydrological processes. With recent international efforts guiding the development of long-term and globally distributed flux estimates, continued product assessments are required to inform upon the selection of suitable model structures and also to establish the appropriateness of these multi-model simulations for global application. In support of the objectives of the GEWEX LandFlux project, four commonly used evaporation models are evaluated against data from tower-based eddy-covariance observations, distributed across a range of biomes and climate zones. The selected schemes include the Surface Energy Balance System (SEBS) approach, the Priestley-Taylor Jet Propulsion Laboratory (PT-JPL) model, the Penman-Monteith based Mu model (PM-Mu) and the Global Land Evaporation: the Amsterdam Methodology (GLEAM). Here we seek to examine the fidelity of global evaporation simulations by examining the multi-model response to varying sources of forcing data. To do this, we perform parallel and collocated model simulations using tower-based data together with a global-scale grid-based forcing product. Through quantifying the multi-model response to high-quality tower data, a better understanding of the subsequent model response to coarse-scale globally gridded data that underlies the LandFlux product can be obtained, while also providing a relative evaluation and assessment of model performance. <br><br> Using surface flux observations from forty-five globally distributed eddy-covariance stations as independent metrics of performance, the tower-based analysis indicated that PT-JPL provided the highest overally statistical performance (0.72; 61 W m<sup>−2</sup>; 0.65), followed closely by GLEAM (0.68; 64 W m<sup>−2</sup>; 0.62), with values in parenthesis representing the <i>R</i><sup>2</sup>, RMSD and Nash-Sutcliffe Efficiency (NSE) and respectively. PM-Mu (0.51; 78 W m<sup>−2</sup>; 0.45) tended to underestimate fluxes, while SEBS (0.72; 101 W m<sup>−2</sup>; 0.24) overestimated values relative to observations. A focused analysis across specific biome types and climate zones showed considerable variability in the performance of all models, with no single model consistently able to outperform any other. Results also indicated that the global gridded data tended to reduce the performance for all of the studied models when compared to the tower data, likely a response to scale mismatch and issues related to forcing quality. Rather than relying on any single model simulation, the spatial and temporal variability at both the tower- and grid-scale highlighted the potential benefits of developing an ensemble or blended evaporation product for global scale LandFlux applications. Challenges related to the robust assessment of the LandFlux product are also discussed.en
dc.language.isoenen
dc.publisherCopernicus GmbHen
dc.relation.urlhttp://www.geosci-model-dev-discuss.net/8/6809/2015/en
dc.rightsThis work is distributed under the Creative Commons Attribution 3.0 License.en
dc.titleThe GEWEX LandFlux project: evaluation of model evaporation using tower-based and globally-gridded forcing dataen
dc.typeArticleen
dc.contributor.departmentBiological and Environmental Sciences and Engineering (BESE) Divisionen
dc.identifier.journalGeoscientific Model Development Discussionsen
dc.eprint.versionPublisher's Version/PDFen
dc.contributor.institutionEstellus, Paris, Franceen
dc.contributor.institutionDepartment of Earth Sciences, VU University Amsterdam, Amsterdam, the Netherlandsen
dc.contributor.institutionInstitute for Atmospheric and Climate Sciences, ETH Zurich, Zurich, Switzerlanden
dc.contributor.institutionDepartment of Civil and Environmental Engineering, Princeton University, Princeton, USAen
dc.contributor.affiliationKing Abdullah University of Science and Technology (KAUST)en
kaust.authorMcCabe, Matthewen
kaust.authorErshadi, Alien
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