Global CO₂ fluxes derived from NISMON-CO₂ and satellite XCO₂

Suman Maity (orcid.org/0000-0002-9274-9021)
Earth System Division, National Institute for Environmental Studies (NIES)

2026/04/14

2010/01/01 - 2025/12/31

NIES
Email: cgerdb_admin(at)nies.go.jp

NetCDF

474.7 MB

v2026.g1.1 (Last updated: 2026/04/14)

English

surface CO₂ flux

Global

Monthly

1° x 1° (transport model resolution ∼223 km)

[ver.2026.g1.1] This dataset was produced by an inverse calculation of NISMON-CO2 with NIES GOSAT SWIR L2 product (V03.05). In NISMON-CO₂, a BFGS-based quasi-Newtonian method was employed for the optimization (Fujii, 2005; Niwa, Fujii et al., 2017). The NICAM-TM simulations were performed with a spatial resolution of glevel-5 (the mean grid interval is ∼223 km). In the inverse analysis, deviations from the prior fluxes were optimized. Here, fossil fuel emissions, which are derived from GCP-GridFED (Jones et al., 2025), were fixed and the other components were optimized. The version of the GCP-GridFED data used is v2025.1. Specifically, scaling factors applied to gross primary production (GPP), respiration (RE), and fire fluxes were optimized at a monthly interval, while annual scaling factors applied to long-term mean net fluxes were optimized for the oceans. For the prior terrestrial fluxes, GPP, RE data of VISIT (Ito, 2021), and fire emission data of GBEIv2022c (Shiraishi et al., 2021; Shiraishi and Hirata, 2021) were used. Meanwhile, the JMA air-sea flux dataset (Iida et al., 2015, 2021) was used for the prior ocean fluxes. The period of the inverse calculation starts at January 2009 and ends at December, 2025. Result during 2009 is considered as spin-up and excluded from the analysis dataset here. Note that the fluxes were optimized on the 1°×1° grids, instead of the atmospheric transport model grids.

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[2026/04/14]

Suman Maity (orcid.org/0000-0002-9274-9021)
Earth System Division, National Institute for Environmental Studies (NIES)

Yosuke Niwa (orcid.org/0000-0002-7600-9816)
Earth System Division, National Institute for Environmental Studies (NIES)

This work used computational resources of the supercomputer Fugaku provided by the RIKEN Center for Computational Science (Project ID: hp250024) and the supercomputer NEC SX-Aurora TSUBASA at NIES. We also acknowledge the NIES GOSAT team for providing XCO₂ data. Additionally, we also thank the data providers of GridFED (Matthew W. Jones), GBEI (Tomohiro Shiraishi, Ryuichi Hirata, Makoto Saito), JMA ocean flux (Yosuke Iida), and VISIT (Akihiko Ito) for supplying valuable CO₂ flux datasets, which are used in this inversion as prior estimates. This study is partly supported by the Environment Research and Technology Development Fund of the Environmental Restoration and Conservation Agency (JPMEERF24S12200), provided by Ministry of the Environment of Japan.

Inversion_document.ver.2026.1.docx
Download supplemental materials

Maity, S., Niwa, Y., Saeki, T., Someya, Y., Yoshida, Y. (2026) Drivers of 2023–2024 atmospheric CO₂ growth: role of northern mid-to-high latitude land carbon cycle, Geophys. Res. Lett.

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

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

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

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