Evaluating the national CO2 budgets of East Asian countries (2015-2022) using the top-down approach

he precise estimation and verification of country-specific net carbon exchange are growing in importance for meeting greenhouse gas reduction targets outlined in the Paris Agreement. In the East Asian region, carbon dioxide emissions account for more than one-third of global emissions; however, the values remain highly uncertain. This study aims to calculate the country-specific Net Carbon Exchange (NCE) for the years 2015–2022 in three East Asian countries—Korea, Japan, and China—using a top-down assessment approach. We utilize the atmospheric inversion system developed based on Geos-Chem adjoint v35j to assimilate OCO-2 XCO2 retrievals, generating net carbon flux. These values compare with national emission inventory data reported to the IPCC and forest growing stock form the National Forest Inventory. We evaluate the national CO2 budgets for the three East Asian countries and analyze the spatial and temporal variations in carbon fluxes.