Emission estimates of ozone-depleting hydrochlorofluorocarbons for China inferred from new observations and inverse modeling

Hydrochlorofluorocarbons (HCFCs), the substitute for chlorofluorocarbons, are regulated under the Montreal Protocol on Substances that Deplete the Ozone Layer. China is considered an emission hot region of HCFCs; however, observations and emission estimates are insufficient, with the need of higher sensitivities of new observations to constrain emissions beyond 2021. To better quantify China's HCFC emissions, we build a new atmospheric site named Changdao (CHD), which is more sensitive to emissions in northern China than previously-used sites. Using these measurements, we provide the most recent emission estimates for China in 2022: 150 ± 13 Gg yr⁻¹ for HCFC-22, 31 ± 2.5 Gg yr⁻¹ for HCFC-141b, and 8.8 ± 0.8 Gg yr⁻¹ for HCFC-142b. We find that China contributed nearly half of the global HCFC emissions in 2022. Our continuous observations since 2022 will assist in assessing compliance with the Montreal Protocol and supporting the timely recovery of the ozone layer.