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Covariation of Airborne Biogenic Tracers (CO₂, COS, and CO) Supports Stronger Than Expected Growing Season Photosynthetic Uptake in the Southeastern US

Parazoo, Nicholas C. and Bowman, Kevin W. and Baier, Bianca C. and Liu, Junjie and Lee, Meemong and Kuai, Le and Shiga, Yoichi and Baker, Ian and Whelan, Mary E. and Feng, Sha and Krol, Maarten and Sweeney, Colm and Runkle, Benjamin R. and Tajfar, Elahe and Davis, Kenneth J. (2021) Covariation of Airborne Biogenic Tracers (CO₂, COS, and CO) Supports Stronger Than Expected Growing Season Photosynthetic Uptake in the Southeastern US. Global Biogeochemical Cycles, 35 (10). Art. No. e2021GB006956. ISSN 0886-6236. doi:10.1029/2021GB006956.

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The Atmospheric Carbon Transport (ACT)-America Earth Venture mission conducted five airborne campaigns across four seasons from 2016 to 2019, to study the transport and fluxes of Greenhouse gases across the eastern United States. Unprecedented spatial sampling of atmospheric tracers (CO₂, carbon monoxide [CO], carbonyl sulfide [COS]) related to biospheric processes offers opportunities to improve our qualitative and quantitative understanding of seasonal and spatial patterns of biospheric carbon uptake. Here, we examine co-variation of boundary layer enhancements of CO₂, CO, and COS across three diverse regions: the crop-dominated Midwest, evergreen-dominated South, and deciduous broadleaf-dominated Northeast. To understand the biogeochemical processes controlling these tracers, we compare the observed co-variation to simulated co-variation resulting from model- and satellite- constrained surface carbon fluxes. We found indication of a common terrestrial biogenic sink of CO₂ and COS and secondary production of CO from biogenic sources in summer throughout the eastern US, driven by stomatal conductance. Upper Midwest crops drive ΔCO₂ and ΔCOS depletion from early to late summer. Northeastern temperate forests drive ΔCO₂ and ΔCOS depletion in late summer. The unprecedented ACT-America flask samples uncovered evidence that southern humid temperate forests photosynthesize and absorb CO₂ and COS, and emit CO precursors, deep into the growing season. Satellite- constrained carbon fluxes capture much of the observed seasonal and spatial variability, but underestimate the magnitude of net CO₂ and COS depletion in the South, indicating a stronger than expected net sink of CO₂ in late summer. Additional sampling of the South will more accurately constrain underlying biological processes and climate sensitivities governing southern carbon dynamics.

Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi. org/10.1029/2021GB006956DOIArticle
Parazoo, Nicholas C.0000-0002-4424-7780
Bowman, Kevin W.0000-0002-8659-1117
Baier, Bianca C.0000-0003-0379-9180
Liu, Junjie0000-0002-7184-6594
Lee, Meemong0000-0002-8797-8209
Kuai, Le0000-0001-6406-1150
Shiga, Yoichi0000-0001-8569-6841
Baker, Ian0000-0001-5162-1956
Whelan, Mary E.0000-0002-2067-1835
Feng, Sha0000-0002-2376-0868
Krol, Maarten0000-0002-3506-2477
Sweeney, Colm0000-0001-9568-0050
Runkle, Benjamin R.0000-0002-2583-1199
Tajfar, Elahe0000-0001-8023-4154
Davis, Kenneth J.0000-0002-1992-8381
Alternate Title:Covariation of Airborne Biogenic Tracers (CO2, COS, and CO) Supports Stronger Than Expected Growing Season Photosynthetic Uptake in the Southeastern US
Additional Information:© 2021. American Geophysical Union. Issue Online: 29 September 2021. Version of Record online: 29 September 2021. Accepted manuscript online: 12 September 2021. Manuscript accepted: 07 September 2021. Manuscript revised: 25 August 2021. Manuscript received: 22 January 2021. The Atmospheric Carbon and Transport (ACT) - America project is a NASA Earth Venture Suborbital 2 project funded by NASA's Earth Science Division. Nicholas Parazoo and Kevin Bowman were supported in part by the NASA Earth Venture Suborbital 2 project and CMS-Flux (16-CMS16-0027). Penn State investigators were supported by NASA Grant NNX15AG76G. Bianca Baier acknowledges CIRES ACT grant number NNX15AJ06G. We acknowledge Arlyn Andrews and Kirk Thoning for provision of gridded HYSPLIT footprints in netCDF format, NOAA/GML laboratory personnel who have conducted measurements of CO₂/CO/COS in flasks for ACT flasks and network sites, and especially Ben Miller for making COS measurements during ACT-America and conducting the QA/QC on the contaminated flask samples. We would like to thank A. Anthony Bloom for intellectual and technical contributions concerning CARDAMOM and its role in predicted tracer-tracer relationships. Maarten Krol is supported by funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program under grant agreement No 742798 ( We thank the following Delta Flux site PI's for their eddy covariance datasets presented in the supplemental information section: M.L. Reba, USDA-ARS, Delta Water Management Research Unit, Jonesboro, AR; J. Bhattacharjee, Dep. of Biology, Univ. of Louisiana, Monroe, LA; K.A. Novick, School of Public and Environmental Affairs, Indiana Univ., Bloomington, IN; P.M. White, Jr., USDA-ARS, Sugarcane Research Unit, Houma, LA. A portion of this study was conceived at the 2017 Keck Institute for Space Studies workshop “Next Generation Approach for Detecting Climate-Carbon Feedbacks: Space-Based Integration of Carbonyl Sulfide (OCS), CO₂, and Solar Induced Fluorescence (SIF).” This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA). © 2021.
Group:Keck Institute for Space Studies
Funding AgencyGrant Number
European Research Council (ERC)742798
Keck Institute for Space Studies (KISS)UNSPECIFIED
Subject Keywords:carbon cycle; carbonyl sulfide; carbon monoxide; ecosystem; OCO₂; act-America
Issue or Number:10
Record Number:CaltechAUTHORS:20211105-172811322
Persistent URL:
Official Citation:Parazoo, N. C., Bowman, K. W., Baier, B. C., Liu, J., Lee, M., Kuai, L., et al. (2021). Covariation of airborne biogenic tracers (CO2, COS, and CO) supports stronger than expected growing season photosynthetic uptake in the southeastern US. Global Biogeochemical Cycles, 35, e2021GB006956.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:111766
Deposited By: Iryna Chatila
Deposited On:05 Nov 2021 20:57
Last Modified:05 Nov 2021 20:57

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