Impact of Air-Sea Exchanges on Air Quality in Coastal Megacities – SEA-M

More than half of the world’ population lives in coastal areas, and three-quarters of all large cities are located on the coast. The impact of coastal megacities (city with a population of over 10 millions) on the environment is significant due to their rapid development, high population densities and large consump-tion of their residents, creating hot-spots of pollution as those encountered in the south East Asia like the Pearl River delta including Hong Kong.

The key feature that drives the science in this project is the potential impact of air-sea exchanges as potential sources of traces gases lending to worsening air quality in heavily polluted megacities. Consider-ing interactions of urban air pollution and marine boundary layer surface chemistry simultaneously should reveal important physical and chemical processes not yet taken into account. In the frame of this joint ANR-RGC project, we propose to explore these processes by means of laboratory based investigations, dedicated field experimentations in Hong Kong, and modeling efforts. Our focus is on the coupling of ur-ban air pollution with sea-surface chemistry, which has only been sparsely explored so far. Specifically, we will investigate (1) production of organic gases and particles at sea surface impacted by urban pollution, (2) atmospheric chemistry of halogen-NOx-VOC and its impact on radical budget and formation of sec-ondary chemicals, and (3) the interplay of sea-air exchange chemicals and sea-land breeze circulation and its impact the air quality ( ozone and particulate matter) in coastal megacities. This project will produce new knowledge of chemical reactions/sources for trace gases at sea surface and in the overlaying atmos-phere and will improve the ability in prediction of air quality for coastal megacities.

The project team has rich experience in atmospheric chemistry and air quality research, possesses complementary expertise and skills and has had close collaborations before. We anticipate major break-through in science and close collaboration between researchers in France and Hong Kong.