Seasonality in aerodynamic resistance across a range of North American ecosystems

Adam M. Young; Mark A. Friedl; Bijan Seyednasrollah; Eric Beamesderfer; Carlos M. Carrillo; Xiaolu Li; Minkyu Moon; M. Altaf Arain; Dennis D. Baldocchi; Peter D. Blanken; Gil Bohrer; Sean P. Burns; Housen Chu; Ankur R. Desai; Timothy J. Griffis; David Y. Hollinger; Marcy E. Litvak; Kim Novick; Russell L. Scott; Andrew E. Suyker; Joseph Verfaillie; Jeffrey D Wood; Andrew D. Richardson

doi:10.1016/j.agrformet.2021.108613

Seasonality in aerodynamic resistance across a range of North American ecosystems

Adam M. Young, Mark A. Friedl, Bijan Seyednasrollah, Eric Beamesderfer, Carlos M. Carrillo, Xiaolu Li, Minkyu Moon, M. Altaf Arain, Dennis D. Baldocchi, Peter D. Blanken, Gil Bohrer, Sean P. Burns, Housen Chu, Ankur R. Desai, Timothy J. Griffis, David Y. Hollinger, Marcy E. Litvak, Kim Novick, Russell L. Scott, Andrew E. SuykerJoseph Verfaillie, Jeffrey D Wood, Andrew D. Richardson

Soil, Water, and Climate

Research output: Contribution to journal › Article › peer-review

16 Scopus citations

Abstract

Surface roughness – a key control on land-atmosphere exchanges of heat and momentum – differs between dormant and growing seasons. However, how surface roughness shifts seasonally at fine time scales (e.g., days) in response to changing canopy conditions is not well understood. This study: (1) explores how aerodynamic resistance changes seasonally; (2) investigates what drives these seasonal shifts, including the role of vegetation phenology; and (3) quantifies the importance of including seasonal changes of aerodynamic resistance in “big leaf” models of sensible heat flux (H). We evaluated aerodynamic resistance and surface roughness lengths for momentum (z_0m) and heat (z_0h) using the kB⁻¹ parameter (ln(z_0m/z_0h)). We used AmeriFlux data to obtain surface-roughness estimates, and PhenoCam greenness data for phenology. This analysis included 23 sites and ∼190 site years from deciduous broadleaf, evergreen needleleaf, woody savanna, cropland, grassland, and shrubland plant-functional types (PFTs). Results indicated clear seasonal patterns in aerodynamic resistance to sensible heat transfer (R_ah). This seasonality tracked PhenoCam-derived start-of-season green-up transitions in PFTs displaying the most significant seasonal changes in canopy structure, with R_ah decreasing near green-up transitions. Conversely, in woody savanna sites and evergreen needleleaf forests, patterns in R_ah were not linked to green-up. Our findings highlight that decreases in kB⁻¹ are an important control over R_ah, explaining > 50% of seasonal variation in R_ah across most sites. Decreases in kB⁻¹ during green-up are likely caused by increasing z_0h in response to higher leaf area index. Accounting for seasonal variation in kB⁻¹ is key for predicting H as well; assuming kB⁻¹ to be constant resulted in significant biases that also exhibited strong seasonal patterns. Overall, we found that aerodynamic resistance can be sensitive to phenology in ecosystems having strong seasonality in leaf area, and this linkage is critical for understanding land-atmosphere interactions at seasonal time scales.

Original language	English (US)
Article number	108613
Journal	Agricultural and Forest Meteorology
Volume	310
DOIs	https://doi.org/10.1016/j.agrformet.2021.108613
State	Published - Nov 15 2021

Bibliographical note

Funding Information:
This research was supported by an NSF Macrosystems Biology award (DEB-1702697). We thank AmeriFlux site PIs John Baker, Ken Bible, Christopher Gough, Beverly Law, and Sonia Wharton for making their data publicly available. In addition, funding for AmeriFlux data resources was provided by the U.S. Department of Energy's Office of Science. Additional support was provided by the NASA Ecostress project to D. Baldocchi. We also thank our many PhenoCam site collaborators. Additional site-specific acknowledgments can be found in Table S1. All AmeriFlux data used in this analysis are available at https://ameriflux.lbl.gov/. PhenoCam datasets are from the V2.0 public data release available on the ORNL DAAC (https://doi.org/10.3334/ORNLDAAC/1674). The code used to conduct this analysis is available on Github (https://github.com/amyoun01/aerodynamic_resistance_analysis). The intermediary datasets generated during this analysis are available upon request from the authors.

Funding Information:
This research was supported by an NSF Macrosystems Biology award (DEB-1702697). We thank AmeriFlux site PIs John Baker, Ken Bible, Christopher Gough, Beverly Law, and Sonia Wharton for making their data publicly available. In addition, funding for AmeriFlux data resources was provided by the U.S. Department of Energy's Office of Science. Additional support was provided by the NASA Ecostress project to D. Baldocchi. We also thank our many PhenoCam site collaborators. Additional site-specific acknowledgments can be found in Table S1. All AmeriFlux data used in this analysis are available at https://ameriflux.lbl.gov/ . PhenoCam datasets are from the V2.0 public data release available on the ORNL DAAC ( https://doi.org/10.3334/ORNLDAAC/1674 ). The code used to conduct this analysis is available on Github ( https://github.com/amyoun01/aerodynamic_resistance_analysis ). The intermediary datasets generated during this analysis are available upon request from the authors.

Publisher Copyright:
© 2021 Elsevier B.V.

Keywords

Aerodynamic resistance
AmeriFlux
Land-atmosphere interactions
PhenoCam
Phenology
Sensible heat flux

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10.1016/j.agrformet.2021.108613

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Young, A. M., Friedl, M. A., Seyednasrollah, B., Beamesderfer, E., Carrillo, C. M., Li, X., Moon, M., Arain, M. A., Baldocchi, D. D., Blanken, P. D., Bohrer, G., Burns, S. P., Chu, H., Desai, A. R., Griffis, T. J., Hollinger, D. Y., Litvak, M. E., Novick, K., Scott, R. L., ... Richardson, A. D. (2021). Seasonality in aerodynamic resistance across a range of North American ecosystems. Agricultural and Forest Meteorology, 310, Article 108613. https://doi.org/10.1016/j.agrformet.2021.108613

Young, AM, Friedl, MA, Seyednasrollah, B, Beamesderfer, E, Carrillo, CM, Li, X, Moon, M, Arain, MA, Baldocchi, DD, Blanken, PD, Bohrer, G, Burns, SP, Chu, H, Desai, AR, Griffis, TJ, Hollinger, DY, Litvak, ME, Novick, K, Scott, RL, Suyker, AE, Verfaillie, J, Wood, JD & Richardson, AD 2021, 'Seasonality in aerodynamic resistance across a range of North American ecosystems', Agricultural and Forest Meteorology, vol. 310, 108613. https://doi.org/10.1016/j.agrformet.2021.108613

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title = "Seasonality in aerodynamic resistance across a range of North American ecosystems",

abstract = "Surface roughness – a key control on land-atmosphere exchanges of heat and momentum – differs between dormant and growing seasons. However, how surface roughness shifts seasonally at fine time scales (e.g., days) in response to changing canopy conditions is not well understood. This study: (1) explores how aerodynamic resistance changes seasonally; (2) investigates what drives these seasonal shifts, including the role of vegetation phenology; and (3) quantifies the importance of including seasonal changes of aerodynamic resistance in “big leaf” models of sensible heat flux (H). We evaluated aerodynamic resistance and surface roughness lengths for momentum (z0m) and heat (z0h) using the kB−1 parameter (ln(z0m/z0h)). We used AmeriFlux data to obtain surface-roughness estimates, and PhenoCam greenness data for phenology. This analysis included 23 sites and ∼190 site years from deciduous broadleaf, evergreen needleleaf, woody savanna, cropland, grassland, and shrubland plant-functional types (PFTs). Results indicated clear seasonal patterns in aerodynamic resistance to sensible heat transfer (Rah). This seasonality tracked PhenoCam-derived start-of-season green-up transitions in PFTs displaying the most significant seasonal changes in canopy structure, with Rah decreasing near green-up transitions. Conversely, in woody savanna sites and evergreen needleleaf forests, patterns in Rah were not linked to green-up. Our findings highlight that decreases in kB−1 are an important control over Rah, explaining > 50% of seasonal variation in Rah across most sites. Decreases in kB−1 during green-up are likely caused by increasing z0h in response to higher leaf area index. Accounting for seasonal variation in kB−1 is key for predicting H as well; assuming kB−1 to be constant resulted in significant biases that also exhibited strong seasonal patterns. Overall, we found that aerodynamic resistance can be sensitive to phenology in ecosystems having strong seasonality in leaf area, and this linkage is critical for understanding land-atmosphere interactions at seasonal time scales.",

keywords = "Aerodynamic resistance, AmeriFlux, Land-atmosphere interactions, PhenoCam, Phenology, Sensible heat flux",

author = "Young, {Adam M.} and Friedl, {Mark A.} and Bijan Seyednasrollah and Eric Beamesderfer and Carrillo, {Carlos M.} and Xiaolu Li and Minkyu Moon and Arain, {M. Altaf} and Baldocchi, {Dennis D.} and Blanken, {Peter D.} and Gil Bohrer and Burns, {Sean P.} and Housen Chu and Desai, {Ankur R.} and Griffis, {Timothy J.} and Hollinger, {David Y.} and Litvak, {Marcy E.} and Kim Novick and Scott, {Russell L.} and Suyker, {Andrew E.} and Joseph Verfaillie and Wood, {Jeffrey D} and Richardson, {Andrew D.}",

note = "Funding Information: This research was supported by an NSF Macrosystems Biology award (DEB-1702697). We thank AmeriFlux site PIs John Baker, Ken Bible, Christopher Gough, Beverly Law, and Sonia Wharton for making their data publicly available. In addition, funding for AmeriFlux data resources was provided by the U.S. Department of Energy's Office of Science. Additional support was provided by the NASA Ecostress project to D. Baldocchi. We also thank our many PhenoCam site collaborators. Additional site-specific acknowledgments can be found in Table S1. All AmeriFlux data used in this analysis are available at https://ameriflux.lbl.gov/. PhenoCam datasets are from the V2.0 public data release available on the ORNL DAAC (https://doi.org/10.3334/ORNLDAAC/1674). The code used to conduct this analysis is available on Github (https://github.com/amyoun01/aerodynamic_resistance_analysis). The intermediary datasets generated during this analysis are available upon request from the authors. Funding Information: This research was supported by an NSF Macrosystems Biology award (DEB-1702697). We thank AmeriFlux site PIs John Baker, Ken Bible, Christopher Gough, Beverly Law, and Sonia Wharton for making their data publicly available. In addition, funding for AmeriFlux data resources was provided by the U.S. Department of Energy's Office of Science. Additional support was provided by the NASA Ecostress project to D. Baldocchi. We also thank our many PhenoCam site collaborators. Additional site-specific acknowledgments can be found in Table S1. All AmeriFlux data used in this analysis are available at https://ameriflux.lbl.gov/ . PhenoCam datasets are from the V2.0 public data release available on the ORNL DAAC ( https://doi.org/10.3334/ORNLDAAC/1674 ). The code used to conduct this analysis is available on Github ( https://github.com/amyoun01/aerodynamic_resistance_analysis ). The intermediary datasets generated during this analysis are available upon request from the authors. Publisher Copyright: {\textcopyright} 2021 Elsevier B.V.",

year = "2021",

month = nov,

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doi = "10.1016/j.agrformet.2021.108613",

language = "English (US)",

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T1 - Seasonality in aerodynamic resistance across a range of North American ecosystems

AU - Young, Adam M.

AU - Friedl, Mark A.

AU - Seyednasrollah, Bijan

AU - Beamesderfer, Eric

AU - Carrillo, Carlos M.

AU - Li, Xiaolu

AU - Moon, Minkyu

AU - Arain, M. Altaf

AU - Baldocchi, Dennis D.

AU - Blanken, Peter D.

AU - Bohrer, Gil

AU - Burns, Sean P.

AU - Chu, Housen

AU - Desai, Ankur R.

AU - Griffis, Timothy J.

AU - Hollinger, David Y.

AU - Litvak, Marcy E.

AU - Novick, Kim

AU - Scott, Russell L.

AU - Suyker, Andrew E.

AU - Verfaillie, Joseph

AU - Wood, Jeffrey D

AU - Richardson, Andrew D.

N1 - Funding Information: This research was supported by an NSF Macrosystems Biology award (DEB-1702697). We thank AmeriFlux site PIs John Baker, Ken Bible, Christopher Gough, Beverly Law, and Sonia Wharton for making their data publicly available. In addition, funding for AmeriFlux data resources was provided by the U.S. Department of Energy's Office of Science. Additional support was provided by the NASA Ecostress project to D. Baldocchi. We also thank our many PhenoCam site collaborators. Additional site-specific acknowledgments can be found in Table S1. All AmeriFlux data used in this analysis are available at https://ameriflux.lbl.gov/. PhenoCam datasets are from the V2.0 public data release available on the ORNL DAAC (https://doi.org/10.3334/ORNLDAAC/1674). The code used to conduct this analysis is available on Github (https://github.com/amyoun01/aerodynamic_resistance_analysis). The intermediary datasets generated during this analysis are available upon request from the authors. Funding Information: This research was supported by an NSF Macrosystems Biology award (DEB-1702697). We thank AmeriFlux site PIs John Baker, Ken Bible, Christopher Gough, Beverly Law, and Sonia Wharton for making their data publicly available. In addition, funding for AmeriFlux data resources was provided by the U.S. Department of Energy's Office of Science. Additional support was provided by the NASA Ecostress project to D. Baldocchi. We also thank our many PhenoCam site collaborators. Additional site-specific acknowledgments can be found in Table S1. All AmeriFlux data used in this analysis are available at https://ameriflux.lbl.gov/ . PhenoCam datasets are from the V2.0 public data release available on the ORNL DAAC ( https://doi.org/10.3334/ORNLDAAC/1674 ). The code used to conduct this analysis is available on Github ( https://github.com/amyoun01/aerodynamic_resistance_analysis ). The intermediary datasets generated during this analysis are available upon request from the authors. Publisher Copyright: © 2021 Elsevier B.V.

PY - 2021/11/15

Y1 - 2021/11/15

N2 - Surface roughness – a key control on land-atmosphere exchanges of heat and momentum – differs between dormant and growing seasons. However, how surface roughness shifts seasonally at fine time scales (e.g., days) in response to changing canopy conditions is not well understood. This study: (1) explores how aerodynamic resistance changes seasonally; (2) investigates what drives these seasonal shifts, including the role of vegetation phenology; and (3) quantifies the importance of including seasonal changes of aerodynamic resistance in “big leaf” models of sensible heat flux (H). We evaluated aerodynamic resistance and surface roughness lengths for momentum (z0m) and heat (z0h) using the kB−1 parameter (ln(z0m/z0h)). We used AmeriFlux data to obtain surface-roughness estimates, and PhenoCam greenness data for phenology. This analysis included 23 sites and ∼190 site years from deciduous broadleaf, evergreen needleleaf, woody savanna, cropland, grassland, and shrubland plant-functional types (PFTs). Results indicated clear seasonal patterns in aerodynamic resistance to sensible heat transfer (Rah). This seasonality tracked PhenoCam-derived start-of-season green-up transitions in PFTs displaying the most significant seasonal changes in canopy structure, with Rah decreasing near green-up transitions. Conversely, in woody savanna sites and evergreen needleleaf forests, patterns in Rah were not linked to green-up. Our findings highlight that decreases in kB−1 are an important control over Rah, explaining > 50% of seasonal variation in Rah across most sites. Decreases in kB−1 during green-up are likely caused by increasing z0h in response to higher leaf area index. Accounting for seasonal variation in kB−1 is key for predicting H as well; assuming kB−1 to be constant resulted in significant biases that also exhibited strong seasonal patterns. Overall, we found that aerodynamic resistance can be sensitive to phenology in ecosystems having strong seasonality in leaf area, and this linkage is critical for understanding land-atmosphere interactions at seasonal time scales.

AB - Surface roughness – a key control on land-atmosphere exchanges of heat and momentum – differs between dormant and growing seasons. However, how surface roughness shifts seasonally at fine time scales (e.g., days) in response to changing canopy conditions is not well understood. This study: (1) explores how aerodynamic resistance changes seasonally; (2) investigates what drives these seasonal shifts, including the role of vegetation phenology; and (3) quantifies the importance of including seasonal changes of aerodynamic resistance in “big leaf” models of sensible heat flux (H). We evaluated aerodynamic resistance and surface roughness lengths for momentum (z0m) and heat (z0h) using the kB−1 parameter (ln(z0m/z0h)). We used AmeriFlux data to obtain surface-roughness estimates, and PhenoCam greenness data for phenology. This analysis included 23 sites and ∼190 site years from deciduous broadleaf, evergreen needleleaf, woody savanna, cropland, grassland, and shrubland plant-functional types (PFTs). Results indicated clear seasonal patterns in aerodynamic resistance to sensible heat transfer (Rah). This seasonality tracked PhenoCam-derived start-of-season green-up transitions in PFTs displaying the most significant seasonal changes in canopy structure, with Rah decreasing near green-up transitions. Conversely, in woody savanna sites and evergreen needleleaf forests, patterns in Rah were not linked to green-up. Our findings highlight that decreases in kB−1 are an important control over Rah, explaining > 50% of seasonal variation in Rah across most sites. Decreases in kB−1 during green-up are likely caused by increasing z0h in response to higher leaf area index. Accounting for seasonal variation in kB−1 is key for predicting H as well; assuming kB−1 to be constant resulted in significant biases that also exhibited strong seasonal patterns. Overall, we found that aerodynamic resistance can be sensitive to phenology in ecosystems having strong seasonality in leaf area, and this linkage is critical for understanding land-atmosphere interactions at seasonal time scales.

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KW - AmeriFlux

KW - Land-atmosphere interactions

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KW - Phenology

KW - Sensible heat flux

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Seasonality in aerodynamic resistance across a range of North American ecosystems

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