Estimated regional CO2 flux and uncertainty based on an ensemble of atmospheric CO2 inversions
-
Published:2022-07-18
Issue:14
Volume:22
Page:9215-9243
-
ISSN:1680-7324
-
Container-title:Atmospheric Chemistry and Physics
-
language:en
-
Short-container-title:Atmos. Chem. Phys.
Author:
Chandra Naveen, Patra Prabir K.ORCID, Niwa Yousuke, Ito AkihikoORCID, Iida YosukeORCID, Goto Daisuke, Morimoto Shinji, Kondo MasayukiORCID, Takigawa MasayukiORCID, Hajima Tomohiro, Watanabe MichioORCID
Abstract
Abstract. Global and regional sources and sinks of carbon across the earth's
surface have been studied extensively using atmospheric carbon dioxide
(CO2) observations and atmospheric chemistry-transport model (ACTM)
simulations (top-down/inversion method). However, the uncertainties in the
regional flux distributions remain unconstrained due to the lack of
high-quality measurements, uncertainties in model simulations, and
representation of data and flux errors in the inversion systems. Here, we
assess the representation of data and flux errors using a suite of 16
inversion cases derived from a single transport model (MIROC4-ACTM) but
different sets of a priori (bottom-up) terrestrial biosphere and oceanic
fluxes, as well as prior flux and observational data uncertainties (50
sites) to estimate CO2 fluxes for 84 regions over the period 2000–2020.
The inversion ensembles provide a mean flux field that is consistent with
the global CO2 growth rate, land and ocean sink partitioning of
−2.9 ± 0.3 (± 1σ uncertainty on the ensemble mean) and
−1.6 ± 0.2 PgC yr−1, respectively, for the period 2011–2020
(without riverine export correction), offsetting about 22 %–33 % and
16 %–18 % of global fossil fuel CO2 emissions. The rivers carry about
0.6 PgC yr−1 of land sink into the deep ocean, and thus the effective
land and ocean partitioning is −2.3 ± 0.3 and −2.2 ± 0.3,
respectively. Aggregated fluxes for 15 land regions compare reasonably well
with the best estimations for the 2000s (∼ 2000–2009), given
by the REgional Carbon Cycle Assessment and Processes (RECCAP), and all
regions appeared as a carbon sink over 2011–2020. Interannual variability
and seasonal cycle in CO2 fluxes are more consistently derived for two
distinct prior fluxes when a greater degree of freedom (increased prior flux
uncertainty) is given to the inversion system. We have further evaluated the
inversion fluxes using meridional CO2 distributions from independent
(not used in the inversions) aircraft and surface measurements, suggesting
that the ensemble mean flux (model–observation mean ± 1σ
standard deviation = −0.3 ± 3 ppm) is best suited for global and
regional CO2 flux budgets than an individual inversion
(model–observation 1σ standard deviation = −0.35 ± 3.3 ppm).
Using the ensemble mean fluxes and uncertainties for 15 land and 11 ocean
regions at 5-year intervals, we show promise in the capability to track flux
changes toward supporting the ongoing and future CO2 emission
mitigation policies.
Funder
Ministry of Education, Culture, Sports, Science and Technology Environmental Restoration and Conservation Agency
Publisher
Copernicus GmbH
Subject
Atmospheric Science
Reference89 articles.
1. Baker, D. F., Law, R. M., Gurney, K. R., Rayner, P., Peylin, P., Denning, A.
S., Bousquet, P., Bruhwiler, L., Chen, Y.-H., Ciais, P., Fung, I. Y.,
Heimann, M., John, J., Maki, T., Maksyutov, S., Masarie, K., Prather, M.,
Pak, B., Taguchi, S., and Zhu, Z.: TransCom 3 inversion intercomparison:
Impact of transport model errors on the interannual variability of regional
CO2 fluxes, 1988–2003, Global Biogeochem. Cy., 20, GB1002,
https://doi.org/10.1029/2004GB002439, 2006. 2. Baker, D. F., Bösch, H., Doney, S. C., O'Brien, D., and Schimel, D. S.:
Carbon source/sink information provided by column CO2 measurements from the
Orbiting Carbon Observatory, Atmos. Chem. Phys., 10, 4145–4165,
https://doi.org/10.5194/acp-10-4145-2010, 2010. 3. Basu, S., Baker, D. F., Chevallier, F., Patra, P. K., Liu, J., and Miller, J. B.: The impact of transport model differences on CO2 surface flux estimates from OCO-2 retrievals of column average CO2, Atmos. Chem. Phys., 18, 7189–7215, https://doi.org/10.5194/acp-18-7189-2018, 2018 4. Biraud, S. C., Torn, M. S., Smith, J. R., Sweeney, C., Riley, W. J., and
Tans, P. P.: A multi-year record of airborne CO2 observations in the US
Southern Great Plains, Atmos. Meas. Tech., 6, 751–763,
https://doi.org/10.5194/amt-6-751-2013, 2013. 5. Bisht, J. S. H., Machida, T., Chandra, N., Tsuboi, K., Patra, P. K.,
Umezawa, T., Niwa, Y., Sawa, Y., Morimoto, S., Nakazawa, T., Saitoh, N., and
Takigawa, M.: Seasonal Variations of SF6, CO2, CH4, and N2O in the UT/LS
Region due to Emissions, Transport, and Chemistry, J. Geophys. Res.-Atmos.,
126, e2020JD033541, https://doi.org/10.1029/2020JD033541, 2021.
Cited by
27 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献
|
|