Abstract
Understanding what drives the interannual variability (IAV) of the land carbon sink is crucial for improving future predictions of this important, yet uncertain, component of the climate system. While drivers of global and hemispheric-scale net ecosystem exchange (NEE) IAV have been investigated, our understanding of the drivers of NEE IAV at regional scales (e.g. sub-continental, biome-level) is quite poor. Here we explore the biome-level attribution and drivers of North American NEE using inverse estimates derived from a dense network of atmospheric CO2 observations. We find that deciduous broadleaf and mixed forests are the primary regions responsible for North American NEE IAV, which differs from the ecoregions identified for the globe and Northern Hemisphere. We also find that a suite of terrestrial biosphere models (TBMs) do not agree on the dominant biome contributing to NEE IAV, with TBMs falling along an apparent spectrum ranging between those with IAV dominated primarily by forested ecosystems to those with IAV dominated by non-forested ecosystems. Furthermore, this regional trade-off in TBM NEE IAV is found to be linked to differing regional responses to environmental drivers among TBMs. This work displays the importance of extra-tropical forests in driving continental NEE IAV and also highlights the challenges and limitations of using TBMs to inform regional-scale carbon flux dynamics.
| Original language | English |
|---|---|
| Article number | aad505 |
| Journal | Environmental Research Letters |
| Volume | 13 |
| Issue number | 8 |
| DOIs | |
| State | Published - 2018 |
Funding
This work is funded by the National Aeronautics and Space Administration (NASA) under grant numbers NNH14AY37I, NNH16AC91I, 80NSSC18K0165 and NNX13AC48G. Atmospheric and Environmental Research Inc. (AER), and in particular Thomas Nehrkorn, John Henderson, and Janusz Eluszkiewicz, performed the WRF-STILT simulations and provided the sensitivity footprints. Funding for the Multi-scale synthesis and Terrestrial Model Intercomparison Project (MsTMIP; http://nacp.ornl.gov/MsTMIP.shtml) activity was provided through NASA ROSES Grant #NNX10AG01A. Data management support for preparing, documenting, and distributing model driver and output data was performed by the Modeling and Synthesis Thematic Data Center at Oak Ridge National Laboratory (ORNL; http://nacp.ornl.gov), with funding through NASA ROSES Grant #NNH10AN681. Finalized MsTMIP data products are archived at the ORNL DAAC (http://daac.ornl.gov). We acknowledge Nicolas Viovy for the CRU-NCEP data (https://vesg.ipsl.upmc.fr/thredds/catalog/work/p529 viov/cruncep/V8_1901_2016/catalog.html). We acknowledge EUMETSAT for the GOME-2 data and Joanna Joiner for the GOME-2 SIF data originally funded in part by NASA Carbon Cycle Science program grant number NNH10DA001N. We gratefully acknowledge the efforts of the PIs of the various towers providing continuous atmospheric CO2 observations, which were instrumental for these analyses. The sites BRW, WGC, SNP, SCT, AMT, WBI, BAO, LEF and WKT are part of NOAA’s Global Greenhouse Gas Reference Network operated by the Global Monitoring Division of NOAAs EarthSystemResearchLaboratory withadditional support from NOAAs Climate Program Office and are a contribution to the North American Carbon Program. The installation of CO2 sampling equipment was made possible at AMT, by a grant from the National Science Foundation Biocomplexity in the Environment Program (ATM-0221850), at SNP, by the University of Virginia, and at SCT by funding provided by the DOE Office of Science—Terrestrial Carbon Processes program and performed under contract No. DE-AC09-08SR22470. Savannah River National Laboratory (SNRL) is operated by Savannah River Nuclear Solutions, LLC under Contract No. DE-AC09-08SR22470 with the US Department of Energy. WGC measurements were supported by a combination of the California Energy Commission’s Public Interest Environmental Research Program to the Lawrence Berkeley National Laboratory under contract DE-AC02-05CH11231 and NOAA. Research at ACV, AOZ, RKW, RCE, RMM, RRL and RGV was sponsored by the US Department of Energy Office of Science TCP program (DE-FG02-06ER64315) and by the US Department of Commerce, NOAA office of Global Programs (NA08OAR4310533). The five Oregon sites OFR, OMT, OYQ, OMP, ONG were supported by NOAA (NA11OAR4310056). We thank the following individuals for collecting and providing the atmospheric CO2 data from the following sites: Arlyn Andrews (NOAA) for AMT, WBI, BAO, LEF and WKT, Arlyn Andrews (NOAA) and Stephan De Wekker (UVA) for SNP, Kirk Thoning (NOAA) and Pieter Tans (NOAA) for BRW, Arlyn Andrews (NOAA) and Matt J. Parker (SRNL) for SCT, Marc Fischer (LBNL) and Arlyn Andrews (NOAA) for WGC, Kenneth Davis, Scott Richardson and Natasha Miles (The Pennsylvania State University) for AAC, ACR, ACV, AME, AOZ, RKW, RCE, RMM, RRL, RGV, FPK, INX01, and INX09, Britton Stephens (NCAR) and the Regional Atmospheric Continuous CO2 Network in the Rocky Mountains (RACCOON) for NWR, SPL, RBA and HDP, Beverly Law (Oregon State University), Andres Schmidt (RWTH Aachen University) and the TERRA-PNW group for data from 8 Oregon sites, OFR, OMT, OYQ, OMP, ONG, MBO, OSI, OWA, William Munger (Harvard University) and Steven Wofsy (Harvard University) for HFM, Doug Worthy (Environment Canada) for CDL, FRD, WSA, EGB, ETL, LLB, CHM, BCK, ESP, EST, BRA, CBY, CHL, CPS, TPD, and INU, Tim Griffis (UMN) for KCMP, Colm Sweeney (NOAA) for MVY, Sebastien Biraud (LBNL) and Margaret Torn (LBNL) for SGP, and Charles Miller (NASA) and John Miller (NOAA) for CRV. Readers can contact individual data providers for site-specific CO2 concentrations or the author ([email protected]) to access the other data and methods used in this study. This work is funded by the National Aeronautics and Space Administration (NASA) under grant numbers NNH14AY37I, NNH16AC91I, 80NSSC18K0165 and NNX13AC48G. Atmospheric and Environmental Research Inc. (AER), and in particular Thomas Nehrkorn, John Henderson, and Janusz Eluszkiewicz, performed the WRF-STILT simulations and provided the sensitivity footprints. Funding for the Multi-scale synthesis and Terrestrial Model Intercomparison Project (MsTMIP; http://nacp.ornl.gov/MsTMIP.shtml) activity was provided through NASA ROSES Grant #NNX10AG01A. Data management support for preparing, documenting, and distributing model driver and output data was performed by the Modeling and Synthesis Thematic Data Center at Oak Ridge National Laboratory (ORNL; http://nacp.ornl.gov), with funding through NASA ROSES Grant #NNH10AN681. Finalized MsTMIP data products are archived at the ORNL DAAC (http://daac.ornl.gov). We acknowledge Nicolas Viovy for the CRU-NCEP data (https://vesg.ipsl.upmc.fr/thredds/catalog/work/p529 viov/cruncep/V8_1901_2016/catalog.html). We acknowledge EUMETSAT for the GOME-2 data and Joanna Joiner for the GOME-2 SIF data originally funded in part by NASA Carbon Cycle Science program grant number NNH10DA001N. We gratefully acknowledge the efforts of the PIs of the various towers providing continuous atmospheric CO2 observations, which were instrumental for these analyses. The sites BRW, WGC, SNP, SCT, AMT, WBI, BAO, LEF and WKT are part of NOAA's Global Greenhouse Gas Reference Network operated by the Global Monitoring Division of NOAAs Earth System Research Laboratory with additional support from NOAAs Climate Program Office and are a contribution to the North American Carbon Program. The installation of CO2 sampling equipment was made possible at AMT, by a grant from the National Science Foundation Biocomplexity in the Environment Program (ATM-0221850), at SNP, by the University of Virginia, and at SCT by funding provided by the DOE Office of Science-Terrestrial Carbon Processes program and performed under contract No. DE-AC09-08SR22470. Savannah River National Laboratory (SNRL) is operated by Savannah River Nuclear Solutions, LLC under Contract No. DE-AC09-08SR22470 with the US Department of Energy. WGC measurements were supported by a combination of the California Energy Commission's Public Interest Environmental Research Program to the Lawrence Berkeley National Laboratory under contract DE-AC02-05CH11231 and NOAA. Research at ACV, AOZ, RKW, RCE, RMM, RRL and RGV was sponsored by the US Department of Energy Office of Science TCP program (DE-FG02-06ER64315) and by the US Department of Commerce, NOAA office of Global Programs (NA08OAR4310533). The five Oregon sites OFR, OMT, OYQ, OMP, ONG were supported by NOAA (NA11OAR4310056). We thank the following individuals for collecting and providing the atmospheric CO2 data from the following sites: Arlyn Andrews (NOAA) for AMT, WBI, BAO, LEF and WKT, Arlyn Andrews (NOAA) and Stephan De Wekker (UVA) for SNP, Kirk Thoning (NOAA) and Pieter Tans (NOAA) for BRW, Arlyn Andrews (NOAA) and Matt J. Parker (SRNL) for SCT, Marc Fischer (LBNL) and Arlyn Andrews (NOAA) for WGC, Kenneth Davis, Scott Richardson and Natasha Miles (The Pennsylvania State University) for AAC, ACR, ACV, AME, AOZ, RKW, RCE, RMM, RRL, RGV, FPK, INX01, and INX09, Britton Stephens (NCAR) and the Regional Atmospheric Continuous CO2 Network in the Rocky Mountains (RACCOON) for NWR, SPL, RBA and HDP, Beverly Law (Oregon State University), Andres Schmidt (RWTH Aachen University) and the TERRA-PNW group for data from 8 Oregon sites, OFR, OMT, OYQ, OMP, ONG, MBO, OSI, OWA, William Munger (Harvard University) and Steven Wofsy (Harvard University) for HFM, Doug Worthy (Environment Canada) for CDL, FRD, WSA, EGB, ETL, LLB, CHM, BCK, ESP, EST, BRA, CBY, CHL, CPS, TPD, and INU, Tim Griffis (UMN) for KCMP, Colm Sweeney (NOAA) for MVY, Sebastien Biraud (LBNL) and Margaret Torn (LBNL) for SGP, and Charles Miller (NASA) and John Miller (NOAA) for CRV. Readers can contact individual data providers for site-specific CO2 concentrations or the author ([email protected]) to access the other data and methods used in this study.
Keywords
- Atmospheric CO
- Attribution
- Carbon cycle
- Drivers
- Net ecosystem exchange
- Regional scale