1. Joint CO 2 Mole Fraction and Flux Analysis Confirms Missing Processes in CASA Terrestrial Carbon Uptake Over North America
- Author
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Z. Barkley, Kenneth J. Davis, Daniel Wesloh, Ian Baker, Sha Feng, Christopher B. Williams, Yu Zhou, Thomas Lauvaux, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), U.S. Department of Energy, USDOE National Aeronautics and Space Administration, NASA National Oceanic and Atmospheric Administration, NOAA Battelle: DE-AC05-76RL01830 Office of Science, SC Biological and Environmental Research, BER Earth Sciences Division: NNX15AG76G, NNX16AN17G, This work was funded by the NASA ACT‐America project. ACT‐America project is a NASA Earth Venture Suborbital‐2 project funded by NASA’s Earth Science Division (Grant NNX15AG76G to Penn State and NNX16AN17G to Clark University). S. Feng was also partly supported by the Department of Energy (DOE)’s Energy Esascale Earth System Model (E3SM) project, funded by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research. The Pacific Northwest National Laboratory is operated by Battelle Memorial Institute under contract DE‐AC05‐76RL01830. T. Lauvaux was also supported by the French research program Make Our Planet Great Again (project CIUDAD). Many thanks to Andrew R. Jacobson at NOAA Global Monitoring Laboratory (GML) for the feedback on the diel cycle of the CT2017 posterior biogenic CO fluxes. 2, This work was funded by the NASA ACT-America project. ACT-America project is a NASA Earth Venture Suborbital-2 project funded by NASA?s Earth Science Division (Grant NNX15AG76G to Penn State and NNX16AN17G to Clark University). S. Feng was also partly supported by the Department of Energy (DOE)?s Energy Esascale Earth System Model (E3SM) project, funded by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research. The Pacific Northwest National Laboratory is operated by Battelle Memorial Institute under contract DE-AC05-76RL01830. T. Lauvaux was also supported by the French research program Make Our Planet Great Again (project CIUDAD). Many thanks to Andrew R. Jacobson at NOAA Global Monitoring Laboratory (GML) for the feedback on the diel cycle of the CT2017 posterior biogenic CO2 fluxes., and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)
- Subjects
0106 biological sciences ,Atmospheric Science ,Daytime ,010504 meteorology & atmospheric sciences ,Atmospheric sciences ,Mole fraction ,01 natural sciences ,Carbon cycle ,03 medical and health sciences ,0302 clinical medicine ,Flux (metallurgy) ,Environmental Chemistry ,Joint (geology) ,030304 developmental biology ,0105 earth and related environmental sciences ,General Environmental Science ,[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere ,0303 health sciences ,Global and Planetary Change ,010604 marine biology & hydrobiology ,Biosphere ,Inversion (meteorology) ,13. Climate action ,Environmental science ,Sink (computing) ,030217 neurology & neurosurgery - Abstract
International audience; Terrestrial biosphere models (TBMs) play a key role in the detection and attribution of carbon cycle processes at local to global scales and in projections of the coupled carbon-climate system. TBM evaluation commonly involves direct comparison to eddy-covariance flux measurements. We use atmospheric CO2 mole fraction ([CO2]) measured in situ from aircraft and tower, in addition to flux-measurements from summer 2016 to evaluate the Carnegie-Ames-Stanford-Approach (CASA) TBM. WRF-Chem is used to simulate [CO2] using biogenic CO2 fluxes from a CASA parameter-based ensemble and CarbonTracker version 2017 (CT2017) in addition to transport and CO2 boundary condition ensembles. The resulting “super ensemble” of modeled [CO2] demonstrates that the biosphere introduces the majority of uncertainty to the simulations. Both aircraft and tower [CO2] data show that the CASA ensemble net ecosystem exchange (NEE) of CO2 is biased high (NEE too positive) and identify the maximum light use efficiency Emax a key parameter that drives the spread of the CASA ensemble in summer 2016. These findings are verified with flux-measurements. The direct comparison of the CASA flux ensemble with flux-measurements confirms missing sink processes in CASA. Separating the daytime and nighttime flux, we discover that the underestimated net uptake results from missing sink processes that result in overestimation of respiration. NEE biases are smaller in the CT2017 posterior biogenic fluxes, which assimilate observed [CO2]. Flux tower analyses reveal an unrealistic overestimation of nighttime respiration in CT2017 which we attribute to limited flexibility in the inversion strategy.
- Published
- 2021
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