Toward a long-term atmospheric CO2 inversion for elucidating natural carbon fluxes: technical notes of NISMON-CO2 v2021.1

Abstract Accurate estimates of the carbon dioxide (CO 2 ) fluxes at earth’s surface are imperative for comprehending cycle mechanisms and providing reliable global warming predictions. Furthermore, they can also provide valuable science-based information that will be helpful in reducing human-induced CO emissions. Inverse analysis is a prominent method quantitatively estimating spatiotemporal variations fluxes; however, it involves certain level uncertainty requires technical refinement, specifically to improve horizontal resolution so local compared with other made regional or national level. In this study, novel set inversion schemes was incorporated into state-of-the-art inverse system named NISMON-CO . The introduced include grid conversion, observational weighting, anisotropic prior error covariance, details which described. Moreover, pseudo-observation experiments were performed examine effect new assess reliability long-term practical inhomogeneous observations. experiment results evidently demonstrate advantages conversion scheme high-resolution flux (1° × 1°), notable improvements being achieved through weighting covariance. estimated seasonal interannual confirmed reliable, although some potential bias terms land–ocean partitioning observed. Thus, these useful interpreting result from real-observation by ver. 2021.1.