0. Creator
Yosuke Niwa1,2 (niwa.yosuke@nies.go.jp)
1. National Institute for Environmental Studies, Japan
2. Meteorological Research Institute, Japan
1. Inversion system and settings
System nameNISMON-CO2 ver.2023.1(refs: Niwa et al., 2017a,b, 2021, 2022)
Transport model
NICAM-TM (Niwa et al., 2011; Niwa et al., 2017a)
Horizontal resolution: glevel-5 (~223 km)
Vertical layers: 40 (up to ~45km)
Meteorological data: horizontal winds are nudged towards JRA-55 (Kobayashi et al., 2015)
See more references listed below for transport performances.
Flux model
The surface CO2 fluxes that are input to NICAM-TM can be described as𝑓!"! (𝑥, 𝑡) = 𝑓#$% (𝑥, 𝑡) − 𝛽&'' (𝑓&'' (𝑥, 𝑡) + ∆𝑓&'' (𝑥, 𝑡)) + 𝛽() (𝑓() (𝑥, 𝑡) + ∆𝑓() (𝑥, 𝑡))+ 𝑓$*+,- (𝑥, 𝑡) + -1 + ∆𝛼#.-, (𝑥, 𝑡)0𝑓#.-, (𝑥, 𝑡)+ 𝑓$/0 (𝑥, 𝑡) + ∆𝑓$/0 (𝑥, 𝑡),where x and t represent flux location and time, respectively. Fluxes from fossil fuel use andcement production, gross primary production (GPP) and respiration (RE) of terrestrial
biospheres, biomass burning, and oceans are denoted as ffos, fGPP, fRE, ffire, and focn, respectively.
Other minor fluxes (e.g., land use change) are denoted as fother, which are not optimized in theinversion. The above fluxes are prescribed by flux datasets prepared in advance and havemonthly temporal resolution here. The above Δ variables are optimized in the inversion; theirtemporal resolutions are all set monthly except for the ocean flux Δfocn. The coefficients βGPPand βRE are scaling factors that reproduce diurnal variations; they distribute fluxes at 3-hourly
resolution from the monthly fluxes.
Optimization method
POpULar (Fujii and Kamachi, 2003; Fujii, 2005; Niwa et al., 2017b)
a quasi-Newton BFGS method
Prescribed flux
fossil fuel: GCP-GridFEDv2023.1 (Jones et al., 2022)
https://doi.org/10.5281/zenodo.7016360
terrestrial biosphere (GPP, RE, LUC): VISIT (Ito and Inatomi, 2012; Ito, 2019)air-sea exchange: JMA air-sea flux data (Iida et al., 2021)
https://www.data.jma.go.jp/gmd/kaiyou/english/co2_flux/co2_flux_data_en.html
biomass burning: GFEDv4.1s (van der Werf et al., 2017)
Note: For the years GFED does not cover (i.e., 1990-1996), the climatological data were used.
Analysis period
Jan 1990 – Dec 2022

(one year spin-up of Jan 1989 – Dec 1989 and three month spin-down of Jan 2023 – Mar 2023)

References•
Fujii, Y.: Preconditioned Optimizing Utility for Large-dimensional analyses (POpULar), J.
Oceanogr., 61, 167–181, https://doi.org/10.1007/s10872-005-0029-z, 2005.
•Fujii, Y. and Kamachi, M.: A nonlinear preconditioned quasi-Newton method without
inversion of a first-guess covariance matrix in variational analyses, Tellus A, 55, 450–454,
https://doi.org/10.1034/j.1600-0870.2003.00030.x, 2003.

•Iida, Y., Kojima, A., Takatani, Y., Nakano, T., Sugimoto, H., Midorikawa, T., and Ishii, M.:
Trends in pCO2 and sea–air CO2 flux over the global open oceans for the last two decades, J.
Oceanogr., 71, https://doi.org/10.1007/s10872-015-0306-4, 2015.

•Ito, A.: Disequilibrium of terrestrial ecosystem CO2 budget caused by disturbance-induced
emissions and non-CO2 carbon export flows: a global model assessment, Earth System
Dynamics, 10, 685–709, https://doi.org/10.5194/esd-10-685-2019, 2019.

•Ito, A. and Inatomi, M.: Use of a process-based model for assessing the methane budgets ofglobal terrestrial ecosystems and evaluation of uncertainty, Biogeosciences, 9, 759–773,
https://doi.org/10.5194/bg-9-759-2012, 2012.

•Jones, M.W., Andrew, R.M., Peters, G.P., Janssens-Maenhout, G., De-Gol, A. J., Ciais, P., Patra, P.
K., Chevallier, F., and Le Quéré, C.: Gridded fossil CO2 emissions and related O2 combustionconsistent with national inventories 1959–2018, Sci Data 8, 2, https://doi.org/10.1038/s41597020-00779-6, 2021.

•Kobayashi, S., Ota, Y., Harada, Y., Ebita, A., Moriya, M., Onoda, H., Onogi, K., Kamahori, H.,
Kobayashi, C., Endo, H., Miyaoka, K. and Takahashi, K.: The JRA-55 Reanalysis: GeneralSpecifications and Basic Characteristics, J. Meteor. Soc. Japan, 93, 5–48,
https://doi.org/10.2151/jmsj.2015-001, 2015.

•Niwa, Y., Tomita, H., Satoh, M., and Imasu, R.: A Three-Dimensional Icosahedral Grid
Advection Scheme Preserving Monotonicity and Consistency with Continuity for
Atmospheric Tracer Transport, J. Meteor. Soc. Japan, 89, 255–268,
https://doi.org/10.2151/jmsj.2011- 306, 2011.

•Niwa, Y., Tomita, H., Satoh, M., Imasu, R., Sawa, Y., Tsuboi, K., Matsueda, H., Machida, T.,
Sasakawa, M., Belan, B., and Saigusa, N.: A 4D-Var inversion system based on theicosahedral grid model (NICAM-TM 4D-Var v1.0) – Part 1: Offline forward and adjoint
transport models, Geosci. Model Dev., 10, 1157–1174, https://doi.org/10.5194/gmd-101157-2017, 2017a.

•

Niwa, Y., Fujii, Y., Sawa, Y., Iida, Y., Ito, A., Satoh, M., Imasu, R., Tsuboi, K., Matsueda, H., andSaigusa, N.: A 4D-Var inversion system based on the icosahedral grid model (NICAM-TM 4DVar v1.0) – Part 2: Optimization scheme and identical twin experiment of atmospheric CO2
inversion, Geosci. Model Dev., 10, 2201–2219, https://doi.org/10.5194/gmd-10-2201-2017,2017b.

•Niwa, Y., Sawa, Y., Nara, H., Machida, T., Matsueda, H., Umezawa, T., Ito, A., Nakaoka, S.-I.,Tanimoto, H., and Tohjima Y.: Estimation of fire-induced carbon emissions from Equatorial Asia

in 2015 using in situ aircraft and ship observations, Atmos. Chem. Phys., 21, 9455–9473,
https://doi.org/10.5194/acp-21-9455-2021, 2021•

Niwa, Y., Ishijima, K., Ito, A., and Iida, Y.: Toward a long-term atmospheric CO2 inversion forelucidating natural carbon fluxes: technical notes of NISMON-CO2 v2021.1, Prog. Earth Planet
Sci., 9, 42, https://doi.org/10.1186/s40645-022-00502-6, 2022•

Takatani, Y., Enyo, K., Iida, Y., Kojima, A., Nakano, T., Sasano, D., Kosugi, N., Midorikawa, T.,Suzuki, T., and Ishii, M.: Relationships between total alkalinity in surface water and sea
surface dynamic height in the Pacific Ocean, J. Geophys. Res., 119, 2806–2814,
https://doi.org/10.1002/2013jc009739, 2014.

•van der Werf, G. R., Randerson, J. T., Giglio, L., van Leeuwen, T. T., Chen, Y., Rogers, B. M.,Mu, M., van Marle, M. J. E., Morton, D. C., Collatz, G. J., Yokelson, R. J., and Kasibhatla, P. S.:
Global fire emissions estimates during 1997–2016, Earth Syst. Sci. Data, 9, 697–720,
https://doi.org/10.5194/essd-9-697-2017, 2017.

2. Main changes from NISMON-CO2 ver.2022.1•Prior fluxes
Prior terrestrial fluxes include minor fluxes (BVOC and CH4) in addition to GPP, RE and LUC
from VISIT (Ito, 2019). The minor fluxes are not optimized in the inversion.

3. Observations
See observation_list.ver.2023.1.csv.
Basically, all the ObsPack data (obspack_co2_1_GLOBALVIEWplus_v8.0_2022-08-27 (Shuldt etal., 2022) & obspack_co2_1_NRT_v8.2_2023-06-13 (Shuldt et al., 2023)) provided from CSIRO,ECCC, Empa, FMI, IPEN, JMA, LSCE, NCAR, NIES, NILU, NIWA, NOAA, SIO, and TU/NIPR with
obs_flag=1 were used. In addition, the NIES data, which are available from the NIES database
NIES-GED, were also used.
References•Kenneth N. Schuldt, John Mund, Ingrid T. Luijkx, Tuula Aalto, James B. Abshire, Ken Aikin,Arlyn Andrews, Shuji Aoki, Francesco Apadula, Bianca Baier, Peter Bakwin, Jakub Bartyzel,Gilles Bentz, Peter Bergamaschi, Andreas Beyersdorf, Tobias Biermann, Sebastien C. Biraud,
Harald Boenisch, David Bowling, Gordon Brailsford, Willi A. Brand, Huilin Chen, Gao Chen,Lukasz Chmura, Shane Clark, Sites Climadat, Aurelie Colomb, Roisin Commane, SébastienConil, Cedric Couret, Adam Cox, Paolo Cristofanelli, Emilio Cuevas, Roger Curcoll, BruceDaube, Kenneth Davis, Martine De Mazière, Stephan De Wekker, Julian Della Coletta, Marc
Delmotte, Joshua P. DiGangi, Ed Dlugokencky, James W. Elkins, Lukas Emmenegger,Shuangxi Fang, Marc L. Fischer, Grant Forster, Arnoud Frumau, Michal Galkowski, Luciana V.
Gatti, Torsten Gehrlein, Christoph Gerbig, Francois Gheusi, Emanuel Gloor, Vanessa GomezTrueba, Daisuke Goto, Tim Griffis, Samuel Hammer, Chad Hanson, László Haszpra, JuhaHatakka, Martin Heimann, Michal Heliasz, Daniela Heltai, Arjan Hensen, Ove Hermanssen,
Eric Hintsa, Antje Hoheisel, Jutta Holst, Viktor Ivakhov, Dan Jaffe, Armin Jordan, WarrenJoubert, Anna Karion, Stephan R. Kawa, Victor Kazan, Ralph Keeling, Petri Keronen, JooilKim, Tobias Kneuer, Pasi Kolari, Katerina Kominkova, Eric Kort, Elena Kozlova, Paul Krummel,Dagmar Kubistin, Casper Labuschagne, David H. Lam, Xin Lan, Ray Langenfelds, Olivier
Laurent, Tuomas Laurila, Thomas Lauvaux, Jost Lavric, Bev Law, Olivia S. Lee, John Lee, Irene
Lehner, Kari Lehtinen, Reimo Leppert, Ari Leskinen, Markus Leuenberger, Ingeborg Levin,Janne Levula, John Lin, Matthias Lindauer, Zoe Loh, Morgan Lopez, Chris R. Lunder,Toshinobu Machida, Ivan Mammarella, Giovanni Manca, Alistair Manning, Andrew Manning,Michal V. Marek, Melissa Y. Martin, Giordane A. Martins, Hidekazu Matsueda, Kathryn
McKain, Harro Meijer, Frank Meinhardt, Lynne Merchant, N. Mihalopoulos, Natasha Miles,
John B. Miller, Charles E. Miller, Logan Mitchell, Stephen Montzka, Fred Moore, HeikoMoossen, Eric Morgan, Josep-Anton Morgui, Shinji Morimoto, Bill Munger, David Munro,
Cathrine L. Myhre, Meelis Mölder, Jennifer Müller-Williams, Jaroslaw Necki, Sally Newman,Sylvia Nichol, Yosuke Niwa, Simon O'Doherty, Florian Obersteiner, Bill Paplawsky, JeffPeischl, Olli Peltola, Salvatore Piacentino, Jean M. Pichon, Steve Piper, Joseph Pitt, Christian
Plass-Duelmer, Stephen M. Platt, Steve Prinzivalli, Michel Ramonet, Ramon Ramos, EnriqueReyes-Sanchez, Scott Richardson, Haris Riris, Pedro P. Rivas, Michael Rothe, ThomasRyerson, Kazuyuki Saito, Maryann Sargent, Motoki Sasakawa, Bert Scheeren, Martina
Schmidt, Tanja Schuck, Marcus Schumacher, Thomas Seifert, Mahesh K. Sha, Paul Shepson,
Michael Shook, Christopher D. Sloop, Paul Smith, Martin Steinbacher, Britton Stephens,Colm Sweeney, Lise L. Sørensen, Pieter Tans, Kirk Thoning, Helder Timas, Margaret Torn,
Pamela Trisolino, Jocelyn Turnbull, Kjetil Tørseth, Alex Vermeulen, Brian Viner, Gabriela
Vitkova, Stephen Walker, Andrew Watson, Ray Weiss, Steve Wofsy, Justin Worsey, DougWorthy, Dickon Young, Sönke Zaehle, Andreas Zahn, Miroslaw Zimnoch, Rodrigo A. deSouza, Alcide G. di Sarra, Danielle van Dinther, Pim van den Bulk; Multi-laboratorycompilation of atmospheric carbon dioxide data for the period 1957-2021;
obspack_co2_1_GLOBALVIEWplus_v8.0_2022-08-27; NOAA Earth System ResearchLaboratory, Global Monitoring Laboratory. http://doi.org/10.25925/20220808.
•Kenneth N. Schuldt, Andrew R. Jacobson, Tuula Aalto, Arlyn Andrews, Francesco Apadula,Sabrina Arnold, Peter Bakwin, Peter Bergamaschi, Tobias Biermann, Sebastien C. Biraud,
Huilin Chen, Aurelie Colomb, Sébastien Conil, Cédric Couret, Paolo Cristofanelli, Martine De
Mazière, Stephan De Wekker, Marc Delmotte, Lukas Emmenegger, Marc L. Fischer, Grant
Forster, Juha Hatakka, Michal Heliasz, Daniela Heltai, Ove Hermansen, Antje Hoheisel, JuttaHolst, Daniel A. Jaffe, Anna Karion, Victor Kazan, Petri Keronen, Tobias Kneuer, Katerina
Kominkova, Dagmar Kubistin, Xin Lan, Olivier Laurent, Tuomas Laurila, John Lee, Irene
Lehner, Kari Lehtinen, Ari Leskinen, Markus Leuenberger, Matthias Lindauer, Morgan Lopez,
Chris R. Lunder, Ivan Mammarella, Giovanni Manca, Michal V. Marek, Kathryn McKain, Frank
Meinhardt, John B. Miller, Charles E. Miller, Cathrine L. Myhre, Meelis Mölder, Jennifer
Müller-Williams, Salvatore Piacentino, Jean M. Pichon, Penelope Pickers, Joseph Pitt,Christian Plass-Dülmer, Stephen M. Platt, Michel Ramonet, Bert Scheeren, Martina Schmidt,Marcus Schumacher, Mahesh K. Sha, Christopher D. Sloop, Paul D. Smith, Martin
Steinbacher, Colm Sweeney, Lise L. Sørensen, Pieter Tans, Kirk Thoning, Pamela Trisolino,Kjetil Tørseth, Brian Viner, Gabriela Vitkova, Doug Worthy, Alcide G. di Sarra; Multilaboratory compilation of atmospheric carbon dioxide data for the period 2022-2023;
obspack_co2_1_NRT_v8.2_2023-06-13; NOAA Earth System Research Laboratory, Global
Monitoring Laboratory. http://doi.org/10.25925/20230601.

4. Transport model performances
Advection scheme, radon simulation•
Niwa, Y., Tomita, H., Satoh, M., and Imasu, R.: A Three-Dimensional Icosahedral Grid
Advection Scheme Preserving Monotonicity and Consistency with Continuity forAtmospheric Tracer Transport, J. Meteor. Soc. Japan, 89, 255–268,
https://doi.org/10.2151/jmsj.2011- 306, 2011.
SF6 simulation•
Niwa, Y., Machida, T., Sawa, Y., Matsueda, H., Schuck, T. J., Brenninkmeijer, C. A. M., Imasu,R., and Satoh, M.: Imposing strong constraints on tropical terrestrial CO2 fluxes using

passenger aircraft based measurements, J. Geophys. Res., 117,https://doi.org/10.1029/2012JD017474, 2012.
Model intercomparison•Patra, P. K., Law, R. M., Peters, W., Rödenbeck, C., Takigawa, M., Aulagnier, C., Baker, I.,Bergmann, D. J., Bousquet, P., Brandt, J., Bruhwiler, L., Cameron-Smith, P. J., Christensen, J.
H., Delage, F., Denning, A. S., Fan, S., Geels, C., Houweling, S., Imasu, R., Karstens, U., Kawa,
S. R., Kleist, J., Krol, M. C., Lin, S.-J., Lokupitiya, R., Maki, T., Maksyu- tov, S., Niwa, Y., Onishi,R., Parazoo, N., Pieterse, G., Rivier, L., Satoh, M., Serrar, S., Taguchi, S., Vautard, R.,
Vermeulen, A. T., and Zhu, Z.: TransCom model simulations of hourly atmospheric CO2:
Analysis of synoptic-scale variations for the period 2002–2003, Global Biogeochem. Cy., 22,doi:10.1029/2007GB003081, 2008.
•Law, R. M., Peters, W., Rödenbeck, C., Aulagnier, C., Baker, I., Bergmann, D. J., Bousquet, P.,
Brandt, J., Bruhwiler, L., Cameron-Smith, P. J., Christensen, J. H., Delage, F., Denning, A. S.,Fan, S., Geels, C., Houweling, S., Imasu, R., Karstens, U., Kawa, S. R., Kleist, J., Krol, M. C., Lin,S.-J., Lokupitiya, R., Maki, T., Maksyutov, S., Niwa, Y., Onishi, R., Parazoo, N., Patra, P. K.,
Pieterse, G., Rivier, L., Satoh, M., Serrar, S., Taguchi, S., Takigawa, M., Vautard, R.,
Vermeulen, A. T., and Zhu, Z.: TransCom model simulations of hourly atmospheric CO2:
Experimental overview and diurnal cycle results for 2002, Global Biogeochem. Cy., 22,GB3009, doi:10.1029/2007GB003050, 2008.

•Niwa, Y., Patra, P. K., Sawa, Y., Machida, T., Matsueda, H., Belikov, D., Maki, T., Ikegami, M.,Imasu, R., Maksyutov, S., Oda, T., Satoh, M., and Takigawa, M.: Three-dimensional variationsof atmospheric CO2: aircraft measurements and multi-transport model simulations, Atoms.
Chem. Phys., 11, 13 359–13 375, https://doi.org/10.5194/acp-11-13359-2011, 2011.