Publications

Notaro, M.; Jorns, M. J.; Briley, L.: Representation of lake-atmosphere interactions and lake-effect snowfall in the Laurentian Great Lakes Basin among HighResMIP global climate models. In: Journal of the Atmospheric Sciences, vol. 79, iss. 5, pp. 1325-1347, 2022. (Type: Journal Article | Links)

He, F.; Clark, P. U.: Freshwater forcing of the Atlantic Meridional Overturning Circulation revisited. In: Nature Climate Change, vol. 12, pp. 449–454, 2022. (Type: Journal Article | Links)

Vavrus, S. J.; Wang, F.; Block, P.: Rainy season precipitation forecasts in coastal Peru from the North American Multi-Model Ensemble (NMME). In: International Journal of Climatology, 2022. (Type: Journal Article | Links)

Vavrus, S. J.; Alkama, R.: Future trends of Arctic surface wind speeds and their relationship with sea ice in CMIP5 climate model simulations. In: Climate Dynamics, vol. 59, pp. 1833-1848, 2021. (Type: Journal Article | Links)

Kiefer, M. T.; Andresen, J. A.; McCullough, D. G.; Baule, W. J.; Notaro, M.: Extreme minimum temperatures in the Great Lakes region of the United States: A climatology with implications for insect mortality.. In: International Journal of Climatology, pp. 1-20, 2021. (Type: Journal Article | Links)

Sutheimer, Colleen M.; Meunier, Jed; Hotchkiss, Sara C.; Rebitzke, Eric; Radeloff, Volker C.: Historical fire regimes of North American hemiboreal peatlands. In: Forest Ecology and Management, vol. 498, pp. 119561, 2021. (Type: Journal Article | Links)

Vavrus, S. J.; Holland, M. M.: When will the Arctic Ocean become ice-free?. In: Arctic, Antarctic, and Alpine Research, vol. 53, iss. 1, pp. 217-218, 2021. (Type: Journal Article | Links)

Francis, J.; Vavrus, S.: How is rapid Arctic warming influencing weather patterns in lower latitudes?. In: Arctic, Antarctic, and Alpine Research, vol. 53, iss. 1, pp. 219-220, 2021. (Type: Journal Article | Links)

Notaro, M.; Zhong, Y.; Xue, P.; Peters-Lidard, C.; Cruz, C.; Kemp, E.; Kristovich, D.; Kulie, M.; Wang, J.; Huang, C.; Vavrus, S. V.: Cold season performance of the NU-WRF regional climate model in the Great Lakes region. . In: Journal of Hydrometeorology, vol. 22, pp. 2423-2454, 2021. (Type: Journal Article | Links)

Beal, Maxwell R. W.; O'Reilly, Bryan; Hietpas, Kaitlynn R.; Block, Paul: Development of a sub-seasonal cyanobacteria prediction model by leveraging local and global scale predictors. In: Harmful Algae, vol. 108, pp. 102100, 2021. (Type: Journal Article | Abstract | Links)

Alexander, Sarah; Yang, Guang; Addisu, Girmachew; Block, Paul: Forecast-informed reservoir operations to guide hydropower and agriculture allocations in the Blue Nile basin, Ethiopia. In: International Journal of Water Resources Development, vol. 37, no. 2, pp. 208-233, 2021. (Type: Journal Article | Links)

Barrett, Kevin D.; Sanford, Patricia; Hotchkiss, Sara C.: The ecology of testate amoebae and Cladocera in Hawaiian montane peatlands and development of a hydrological transfer function. In: Journal of Paleolimnology, vol. 66, pp. 83–101, 2021. (Type: Journal Article | Abstract | Links)

@article{Barrett2021,

title = {The ecology of testate amoebae and Cladocera in Hawaiian montane peatlands and development of a hydrological transfer function},

author = {Kevin D. Barrett and Patricia Sanford and Sara C. Hotchkiss },

doi = {https://doi.org/10.1007/s10933-021-00188-8},

year = {2021},

date = {2021-04-08},

journal = {Journal of Paleolimnology},

volume = {66},

pages = {83–101},

abstract = {Peatland complexes in the humid highlands of Hawai‘i are vital refuges of biodiversity and freshwater resources. Hawaiian peat deposits are also rare repositories of terrestrial ecosystem archives located in an otherwise vast expanse of ocean. We investigated the potential for researching the paleohydrological history of Hawaiian montane peatlands on Kohala, Hawai‘i Island through analyses of testate amoebae and Cladocera. Surface peat was collected from a variety of ecohydrological habitats (from water pools to hummocks) and analyzed for modern testate amoeba and cladoceran species relative abundance. We identified 54 morphotype taxa from 21 genera of testate amoebae, 4 taxa and genera of littoral Cladocera, and the common peat rotifer Habrotrocha angusticollis. Testate amoeba diversity and morphotype occurrence mirrored observations from many high-latitude peatland studies. Constrained and unconstrained ordinations support the hypothesis that surface moisture, measured as water-table depth, is an important control on the distribution of testate amoebae and Cladocera in Hawaiian peatlands. Transfer functions relying on weighted-averaging and modern analogs were developed to predict water-table depths from species relative abundance data, and these perform well under leave-one-site-out cross-validation: RMSEP = 9.75–10.3 cm, R2 = 0.56–0.62. Including cladoceran abundance data in the calibration dataset produced modest model improvement: RMSEP = 1–8% and R2 = 2–13%. A weighted-average partial-least-squares transfer function was applied to microfossil assemblages from a 0.5 m-long peat core with a 210Pb decay chronology anchored by ten existing measurements of 210Pb activity and a Bayesian statistical framework. Microfossils were well-preserved in the peat core. The water-table depth optima of an abundant down-core taxa, Hyalosphenia subflava, is not precisely constrained in the calibration data set, but estimates match those of other tropical studies. A reconstruction of water-table depth indicates dry early nineteenth-century conditions, wet conditions in the late 19th to early twentieth centuries, followed by progressive drying for much of the twentieth-century. Testate amoeba composition appears to have been sensitive to severe drought in recent decades. The results signal that assemblages of testate amoebae and Cladocera are useful proxies of Hawaiian peatland paleohydrology and should be considered alongside other archives of Hawaiian environmental history.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Close

Peatland complexes in the humid highlands of Hawai‘i are vital refuges of biodiversity and freshwater resources. Hawaiian peat deposits are also rare repositories of terrestrial ecosystem archives located in an otherwise vast expanse of ocean. We investigated the potential for researching the paleohydrological history of Hawaiian montane peatlands on Kohala, Hawai‘i Island through analyses of testate amoebae and Cladocera. Surface peat was collected from a variety of ecohydrological habitats (from water pools to hummocks) and analyzed for modern testate amoeba and cladoceran species relative abundance. We identified 54 morphotype taxa from 21 genera of testate amoebae, 4 taxa and genera of littoral Cladocera, and the common peat rotifer Habrotrocha angusticollis. Testate amoeba diversity and morphotype occurrence mirrored observations from many high-latitude peatland studies. Constrained and unconstrained ordinations support the hypothesis that surface moisture, measured as water-table depth, is an important control on the distribution of testate amoebae and Cladocera in Hawaiian peatlands. Transfer functions relying on weighted-averaging and modern analogs were developed to predict water-table depths from species relative abundance data, and these perform well under leave-one-site-out cross-validation: RMSEP = 9.75–10.3 cm, R2 = 0.56–0.62. Including cladoceran abundance data in the calibration dataset produced modest model improvement: RMSEP = 1–8% and R2 = 2–13%. A weighted-average partial-least-squares transfer function was applied to microfossil assemblages from a 0.5 m-long peat core with a 210Pb decay chronology anchored by ten existing measurements of 210Pb activity and a Bayesian statistical framework. Microfossils were well-preserved in the peat core. The water-table depth optima of an abundant down-core taxa, Hyalosphenia subflava, is not precisely constrained in the calibration data set, but estimates match those of other tropical studies. A reconstruction of water-table depth indicates dry early nineteenth-century conditions, wet conditions in the late 19th to early twentieth centuries, followed by progressive drying for much of the twentieth-century. Testate amoeba composition appears to have been sensitive to severe drought in recent decades. The results signal that assemblages of testate amoebae and Cladocera are useful proxies of Hawaiian peatland paleohydrology and should be considered alongside other archives of Hawaiian environmental history.

Close

Barrett, Kevin D.; Sanford, Patricia; Hotchkiss, Sara C.: The ecology of testate amoebae and Cladocera in Hawaiian montane peatlands and development of a hydrological transfer function. In: Journal of Paleolimnology, vol. 66, no. 2, pp. 83–101, 2021. (Type: Journal Article | Links)

Peters, Shanan E; Rowley, David B: Long-Term Evolution of Earth's Continental Surface Elevation. In: EarthArXiv, 2021. (Type: Journal Article | Abstract | Links)

Lipp, A. G.; et al,: The composition and weathering of the continents over geologic time. In: Geochemical Perspectives Letters, vol. 17, pp. 21-26, 2021. (Type: Journal Article | Abstract | Links)

Vermeuel, Michael P; Cleary, Patricia A; Desai, Ankur R; Bertram, Timothy H: Simultaneous Measurements of O3 and HCOOH Vertical Fluxes Indicate Rapid In-Canopy Terpene Chemistry Enhances O3 Removal Over Mixed Temperate Forests. In: Geophysical Research Letters, vol. 48, no. 3, pp. e2020GL090996, 2021, (e2020GL090996 2020GL090996). (Type: Journal Article | Abstract | Links)

Yang, Guang; Zaitchik, Benjamin; Badr, Hamada; Block, Paul: A Bayesian adaptive reservoir operation framework incorporating streamflow non-stationarity. In: Journal of Hydrology, vol. 594, pp. 125959, 2021, ISSN: 0022-1694. (Type: Journal Article | Abstract | Links)

@article{YANG2021125959,

title = {A Bayesian adaptive reservoir operation framework incorporating streamflow non-stationarity},

author = {Guang Yang and Benjamin Zaitchik and Hamada Badr and Paul Block},

url = {https://www.sciencedirect.com/science/article/pii/S0022169421000068},

doi = {https://doi.org/10.1016/j.jhydrol.2021.125959},

issn = {0022-1694},

year  = {2021},

date = {2021-01-01},

journal = {Journal of Hydrology},

volume = {594},

pages = {125959},

abstract = {Water reservoir operating rules are typically derived based on the assumption of streamflow stationarity, however, this assumption could be undermined by climate change. Adaptive reservoir operation is one of the most effective strategies to support water resources management under non-stationarity, yet until now, adaptive strategies considering non-stationarity across multiple time scales are rarely investigated. We propose an adaptive reservoir operation framework that incorporates streamflow non-stationarity across time scales simultaneously. Specifically, we first decompose the streamflow into four frequency categories to detect non-stationarity features through reservoir operation simulations. Next, we incorporate the non-stationarity information from each frequency category into adaptive reservoir operation by using Bayesian Model Averaging. We apply this framework to reservoir operation of the Grand Ethiopian Renaissance Dam on the Blue Nile River and evaluate its effectiveness with streamflow simulated from 21 general circulation models (GCMs) for two greenhouse gases emission scenarios. We find that streamflow non-stationarity from all GCMs varies by future period and frequency category. The proposed Bayesian adaptive reservoir operation framework can detect streamflow non-stationarity across all frequency categories and predominantly outperforms conventional adaptive strategies, especially in terms of firm power output. In general, firm output increases under the Bayesian framework as the power generation reliability increases. The proposed framework offers a robust approach to identify adaptive strategies for reservoir operation to address streamflow non-stationarity.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Close

Cavender-Bares, Jeannine; B Reich, Peter; A Townsend, Philip; Banerjee, Arindam; Butler, Ethan; Desai, Ankur; Gevens, Amanda; E Hobbie, Sarah; Isbell, Forest; Laliberté, Etienne; Meireles, José Eduardo; Menninger, Holly; P Pavlick, Ryan; Pinto-Ledezma, Jesús; Potter, Caitlin; C Schuman, Meredith; Springer, Nathan; Stefanski, Artur; Trivedi, Pankaj; Trowbridge, Amy; Williams, Laura; G Willis, Charles; Yang, Ya: BII-Implementation: The causes and consequences of plant biodiversity across scales in a rapidly changing world. In: Research Ideas and Outcomes, vol. 7, pp. e63850, 2021. (Type: Journal Article | Abstract | Links)

@article{10.3897/rio.7.e63850,

title = {BII-Implementation: The causes and consequences of plant biodiversity across scales in a rapidly changing world},

author = {Jeannine Cavender-Bares and Peter B Reich and Philip A Townsend and Arindam Banerjee and Ethan Butler and Ankur Desai and Amanda Gevens and Sarah E Hobbie and Forest Isbell and Etienne Laliberté and José Eduardo Meireles and Holly Menninger and Ryan P Pavlick and Jesús Pinto-Ledezma and Caitlin Potter and Meredith C Schuman and Nathan Springer and Artur Stefanski and Pankaj Trivedi and Amy Trowbridge and Laura Williams and Charles G Willis and Ya Yang},

url = {https://doi.org/10.3897/rio.7.e63850},

doi = {10.3897/rio.7.e63850},

year  = {2021},

date = {2021-01-01},

journal = {Research Ideas and Outcomes},

volume = {7},

pages = {e63850},

publisher = {Pensoft Publishers},

abstract = {The proposed Biology Integration Institute will bring together two major research institutions in the Upper Midwest—the University of Minnesota (UMN) and University of Wisconsin-Madison (UW)—to investigate the causes and consequences of plant biodiversity across scales in a rapidly changing world—from genes and molecules within cells and tissues to communities, ecosystems, landscapes and the biosphere. The Institute focuses on plant biodiversity, defined broadly to encompass the heterogeneity within life that occurs from the smallest to the largest biological scales. A premise of the Institute is that life is envisioned as occurring at different scales nested within several contrasting conceptions of biological hierarchies, defined by the separate but related fields of physiology, evolutionary biology and ecology. The Institute will emphasize the use of ‘spectral biology’—detection of biological properties based on the interaction of light energy with matter—and process-oriented predictive models to investigate the processes by which biological components at one scale give rise to emergent properties at higher scales. Through an iterative process that harnesses cutting edge technologies to observe a suite of carefully designed empirical systems—including the National Ecological Observatory Network (NEON) and some of the world’s longest running and state-of-the-art global change experiments—the Institute will advance biological understanding and theory of the causes and consequences of changes in biodiversity and at the interface of plant physiology, ecology and evolution.INTELLECTUAL MERITThe Institute brings together a diverse, gender-balanced and highly productive team with significant leadership experience that spans biological disciplines and career stages and is poised to integrate biology in new ways. Together, the team will harness the potential of spectral biology, experiments, observations and synthetic modeling in a manner never before possible to transform understanding of how variation within and among biological scales drives plant and ecosystem responses to global change over diurnal, seasonal and millennial time scales. In doing so, it will use and advance state-of-the-art theory. The institute team posits that the designed projects will unearth transformative understanding and biological rules at each of the various scales that will enable an unprecedented capacity to discern the linkages between physiological, ecological and evolutionary processes in relation to the multi-dimensional nature of biodiversity in this time of massive planetary change. A strength of the proposed Institute is that it leverages prior federal investments in research and formalizes partnerships with foreign institutions heavily invested in related biodiversity research. Most of the planned projects leverage existing research initiatives, infrastructure, working groups, experiments, training programs, and public outreach infrastructure, all of which are already highly synergistic and collaborative, and will bring together members of the overall research and training team.BROADER IMPACTSA central goal of the proposed Institute is to train the next generation of diverse integrative biologists. Post-doctoral, graduate student and undergraduate trainees, recruited from non-traditional and underrepresented groups, including through formal engagement with Native American communities, will receive a range of mentoring and training opportunities. Annual summer training workshops will be offered at UMN and UW as well as training experiences with the Global Change and Biodiversity Research Priority Program (URPP-GCB) at the University of Zurich (UZH) and through the Canadian Airborne Biodiversity Observatory (CABO). The Institute will engage diverse K-12 audiences, the general public and Native American communities through Market Science modules, Minute Earth videos, a museum exhibit and public engagement and educational activities through the Bell Museum of Natural History, the Cedar Creek Ecosystem Science Reserve (CCESR) and the Wisconsin Tribal Conservation Association.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Close

The proposed Biology Integration Institute will bring together two major research institutions in the Upper Midwest—the University of Minnesota (UMN) and University of Wisconsin-Madison (UW)—to investigate the causes and consequences of plant biodiversity across scales in a rapidly changing world—from genes and molecules within cells and tissues to communities, ecosystems, landscapes and the biosphere. The Institute focuses on plant biodiversity, defined broadly to encompass the heterogeneity within life that occurs from the smallest to the largest biological scales. A premise of the Institute is that life is envisioned as occurring at different scales nested within several contrasting conceptions of biological hierarchies, defined by the separate but related fields of physiology, evolutionary biology and ecology. The Institute will emphasize the use of ‘spectral biology’—detection of biological properties based on the interaction of light energy with matter—and process-oriented predictive models to investigate the processes by which biological components at one scale give rise to emergent properties at higher scales. Through an iterative process that harnesses cutting edge technologies to observe a suite of carefully designed empirical systems—including the National Ecological Observatory Network (NEON) and some of the world’s longest running and state-of-the-art global change experiments—the Institute will advance biological understanding and theory of the causes and consequences of changes in biodiversity and at the interface of plant physiology, ecology and evolution.INTELLECTUAL MERITThe Institute brings together a diverse, gender-balanced and highly productive team with significant leadership experience that spans biological disciplines and career stages and is poised to integrate biology in new ways. Together, the team will harness the potential of spectral biology, experiments, observations and synthetic modeling in a manner never before possible to transform understanding of how variation within and among biological scales drives plant and ecosystem responses to global change over diurnal, seasonal and millennial time scales. In doing so, it will use and advance state-of-the-art theory. The institute team posits that the designed projects will unearth transformative understanding and biological rules at each of the various scales that will enable an unprecedented capacity to discern the linkages between physiological, ecological and evolutionary processes in relation to the multi-dimensional nature of biodiversity in this time of massive planetary change. A strength of the proposed Institute is that it leverages prior federal investments in research and formalizes partnerships with foreign institutions heavily invested in related biodiversity research. Most of the planned projects leverage existing research initiatives, infrastructure, working groups, experiments, training programs, and public outreach infrastructure, all of which are already highly synergistic and collaborative, and will bring together members of the overall research and training team.BROADER IMPACTSA central goal of the proposed Institute is to train the next generation of diverse integrative biologists. Post-doctoral, graduate student and undergraduate trainees, recruited from non-traditional and underrepresented groups, including through formal engagement with Native American communities, will receive a range of mentoring and training opportunities. Annual summer training workshops will be offered at UMN and UW as well as training experiences with the Global Change and Biodiversity Research Priority Program (URPP-GCB) at the University of Zurich (UZH) and through the Canadian Airborne Biodiversity Observatory (CABO). The Institute will engage diverse K-12 audiences, the general public and Native American communities through Market Science modules, Minute Earth videos, a museum exhibit and public engagement and educational activities through the Bell Museum of Natural History, the Cedar Creek Ecosystem Science Reserve (CCESR) and the Wisconsin Tribal Conservation Association.

Close

Chu, Housen; Luo, Xiangzhong; Ouyang, Zutao; Chan, Stephen W; Dengel, Sigrid; Biraud, Sébastien C; Torn, Margaret S; Metzger, Stefan; Kumar, Jitendra; Arain, Altaf M; Arkebauer, Tim J; Baldocchi, Dennis; Bernacchi, Carl; Billesbach, Dave; Black, Andrew T; Blanken, Peter D; Bohrer, Gil; Bracho, Rosvel; Brown, Shannon; Brunsell, Nathaniel A; Chen, Jiquan; Chen, Xingyuan; Clark, Kenneth; Desai, Ankur R; Duman, Tomer; Durden, David; Fares, Silvano; Forbrich, Inke; Gamon, John A; Gough, Christopher M; Griffis, Timothy; Helbig, Manuel; Hollinger, David; Humphreys, Elyn; Ikawa, Hiroki; Iwata, Hiroki; Ju, Yang; Knowles, John F; Knox, Sara H; Kobayashi, Hideki; Kolb, Thomas; Law, Beverly; Lee, Xuhui; Litvak, Marcy; Liu, Heping; Munger, William J; Noormets, Asko; Novick, Kim; Oberbauer, Steven F; Oechel, Walter; Oikawa, Patty; Papuga, Shirley A; Pendall, Elise; Prajapati, Prajaya; Prueger, John; Quinton, William L; Richardson, Andrew D; Russell, Eric S; Scott, Russell L; Starr, Gregory; Staebler, Ralf; Stoy, Paul C; Stuart-Haëntjens, Ellen; Sonnentag, Oliver; Sullivan, Ryan C; Suyker, Andy; Ueyama, Masahito; Vargas, Rodrigo; Wood, Jeffrey D; Zona, Donatella: Representativeness of Eddy-Covariance flux footprints for areas surrounding AmeriFlux sites. In: Agricultural and Forest Meteorology, vol. 301-302, pp. 108350, 2021, ISSN: 0168-1923. (Type: Journal Article | Abstract | Links)

@article{CHU2021108350,

title = {Representativeness of Eddy-Covariance flux footprints for areas surrounding AmeriFlux sites},

author = {Housen Chu and Xiangzhong Luo and Zutao Ouyang and Stephen W Chan and Sigrid Dengel and Sébastien C Biraud and Margaret S Torn and Stefan Metzger and Jitendra Kumar and Altaf M Arain and Tim J Arkebauer and Dennis Baldocchi and Carl Bernacchi and Dave Billesbach and Andrew T Black and Peter D Blanken and Gil Bohrer and Rosvel Bracho and Shannon Brown and Nathaniel A Brunsell and Jiquan Chen and Xingyuan Chen and Kenneth Clark and Ankur R Desai and Tomer Duman and David Durden and Silvano Fares and Inke Forbrich and John A Gamon and Christopher M Gough and Timothy Griffis and Manuel Helbig and David Hollinger and Elyn Humphreys and Hiroki Ikawa and Hiroki Iwata and Yang Ju and John F Knowles and Sara H Knox and Hideki Kobayashi and Thomas Kolb and Beverly Law and Xuhui Lee and Marcy Litvak and Heping Liu and William J Munger and Asko Noormets and Kim Novick and Steven F Oberbauer and Walter Oechel and Patty Oikawa and Shirley A Papuga and Elise Pendall and Prajaya Prajapati and John Prueger and William L Quinton and Andrew D Richardson and Eric S Russell and Russell L Scott and Gregory Starr and Ralf Staebler and Paul C Stoy and Ellen Stuart-Haëntjens and Oliver Sonnentag and Ryan C Sullivan and Andy Suyker and Masahito Ueyama and Rodrigo Vargas and Jeffrey D Wood and Donatella Zona},

url = {https://www.sciencedirect.com/science/article/pii/S0168192321000332},

doi = {https://doi.org/10.1016/j.agrformet.2021.108350},

issn = {0168-1923},

year  = {2021},

date = {2021-01-01},

journal = {Agricultural and Forest Meteorology},

volume = {301-302},

pages = {108350},

abstract = {Large datasets of greenhouse gas and energy surface-atmosphere fluxes measured with the eddy-covariance technique (e.g., FLUXNET2015, AmeriFlux BASE) are widely used to benchmark models and remote-sensing products. This study addresses one of the major challenges facing model-data integration: To what spatial extent do flux measurements taken at individual eddy-covariance sites reflect model- or satellite-based grid cells? We evaluate flux footprints—the temporally dynamic source areas that contribute to measured fluxes—and the representativeness of these footprints for target areas (e.g., within 250–3000 m radii around flux towers) that are often used in flux-data synthesis and modeling studies. We examine the land-cover composition and vegetation characteristics, represented here by the Enhanced Vegetation Index (EVI), in the flux footprints and target areas across 214 AmeriFlux sites, and evaluate potential biases as a consequence of the footprint-to-target-area mismatch. Monthly 80% footprint climatologies vary across sites and through time ranging four orders of magnitude from 103 to 107 m2 due to the measurement heights, underlying vegetation- and ground-surface characteristics, wind directions, and turbulent state of the atmosphere. Few eddy-covariance sites are located in a truly homogeneous landscape. Thus, the common model-data integration approaches that use a fixed-extent target area across sites introduce biases on the order of 4%–20% for EVI and 6%–20% for the dominant land cover percentage. These biases are site-specific functions of measurement heights, target area extents, and land-surface characteristics. We advocate that flux datasets need to be used with footprint awareness, especially in research and applications that benchmark against models and data products with explicit spatial information. We propose a simple representativeness index based on our evaluations that can be used as a guide to identify site-periods suitable for specific applications and to provide general guidance for data use.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

Close

Large datasets of greenhouse gas and energy surface-atmosphere fluxes measured with the eddy-covariance technique (e.g., FLUXNET2015, AmeriFlux BASE) are widely used to benchmark models and remote-sensing products. This study addresses one of the major challenges facing model-data integration: To what spatial extent do flux measurements taken at individual eddy-covariance sites reflect model- or satellite-based grid cells? We evaluate flux footprints—the temporally dynamic source areas that contribute to measured fluxes—and the representativeness of these footprints for target areas (e.g., within 250–3000 m radii around flux towers) that are often used in flux-data synthesis and modeling studies. We examine the land-cover composition and vegetation characteristics, represented here by the Enhanced Vegetation Index (EVI), in the flux footprints and target areas across 214 AmeriFlux sites, and evaluate potential biases as a consequence of the footprint-to-target-area mismatch. Monthly 80% footprint climatologies vary across sites and through time ranging four orders of magnitude from 103 to 107 m2 due to the measurement heights, underlying vegetation- and ground-surface characteristics, wind directions, and turbulent state of the atmosphere. Few eddy-covariance sites are located in a truly homogeneous landscape. Thus, the common model-data integration approaches that use a fixed-extent target area across sites introduce biases on the order of 4%–20% for EVI and 6%–20% for the dominant land cover percentage. These biases are site-specific functions of measurement heights, target area extents, and land-surface characteristics. We advocate that flux datasets need to be used with footprint awareness, especially in research and applications that benchmark against models and data products with explicit spatial information. We propose a simple representativeness index based on our evaluations that can be used as a guide to identify site-periods suitable for specific applications and to provide general guidance for data use.

Close

Briley, Laura J; Rood, Richard B; Notaro, Michael: Large lakes in climate models: A Great Lakes case study on the usability of CMIP5. In: Journal of Great Lakes Research, vol. 47, no. 2, pp. 405-418, 2021, ISSN: 0380-1330. (Type: Journal Article | Abstract | Links)