Assessing the Impact of Dimethyl Sulfide (DMS) Emissions on Air Quality in Coastal Chile Using CMAQ Modeling (Student Poster #25)

Abstract Description: Oceans are the predominant biogenic source of global dimethyl sulfide (DMS). They account for more than 97 % of total DMS emissions (anthropogenic and biogenic). Oceanic pollutants such as Sea Salt Aerosols (SSA), DMS and halocarbons play a significant role in biochemistry. DMS contributes to the formation of marine aerosols, and influences cloud albedo and aerosol radiative force. Over the past two decades, many studies on DMS, halocarbons and air quality were focused on United States, China and India, as well as Arctic and Antarctic areas. This is due to the high emission of pollutants in industrialized coastal areas and the study of ice melting, algae and phytoplankton proliferation. Unfortunately, no regional modeling studies have used CMAQ, where oceanic emissions are included to assess atmospheric oxidation at surface-level air in South America, particularly in Chile. This country has an extensive coastline, representing more than 40% of the coastal areas in the region. To analyze the effect of DMS, two coastal cities from Chile are studied, one exposed to anthropogenic and biogenic emissions, and the other primarily affected by biogenic emissions. To estimate the sea/air exchange of DMS, several parameterizations have been evaluated, meanwhile, only one (Liss and Merlivat 1986) is implemented in CMAQ. Accordingly, six DMS parameterizations were applied through the WRF-SMOKE-CMAQ modeling to compare and assess their effect on air quality in these cities. The evaluation involved comparing simulated concentrations of key pollutants—ozone (O3), fine particulate matter (PM2.5), and sulfur dioxide (SO2)—against observational data from air quality monitoring stations in Chile.

Keywords: DMS, CMAQ, Chile