[Seminar] Dr. Haklim Choi

Measurement of atmospheric halogenated compounds and the implication for regional emissions in East Asia

Halogen substances (fluoride, chlorine, bromine, and iodine) are chemical elements that play a fundamental role in the Earth’s atmosphere and are associated with a variety of environmental problems. It is well known that halogens (primarily chlorine and bromine) destroy the Earth’s stratospheric ozone layer and cause the infamous “ozone hole” over Antarctica that was first known in the 1980s. The artificial halogen compounds, chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), are representative ozone-depleting substances (ODSs) that have been produced by industry for a variety of uses such as refrigerants, foam blowing agents, propellants, solvents, and fire retardants. For this reason, the consumption and production of these compounds are regulated by the Montreal Protocol to protect the stratospheric ozone layer. Hydrofluorocarbons (HFCs) as an alternative to CFCs and HCFCs, rapidly increased in use, are greenhouse gases (GHG) thousands of times more powerful than CO2 in terms of global warming potential (GWP). Accordingly, the production and consumption of HFCs in developed and developing countries will be phase-down under the Kyoto Protocol and the Kigali Amendment. In terms of economic and industrial in East Asia, which includes China, Korea, and Japan, these halogen compounds are significant factors influencing the climate system. However, research on emission sources and the quantification of these substances is still insufficient. In this presentation, the abundance of halogenated compounds in the atmosphere will be analyzed that observed at Gosan, a regional monitoring site in East Asia that has been operated since 2008 as a part of the Advanced Global Atmospheric Gases Experiment (AGAGE). Moreover, we introduce the estimated regional and country-specific emissions using not only the Interspecies correlation (ISC) method but also the inversion framework, FLEXINVERT+, which applies a Bayesian optimization method based on the FLEXPART (FLEXible PARTicle) Lagrangian transport and dispersion model.