1003 Plenary-How marine emissions contribute to atmospheric particles, with implications for climate скачать в хорошем качестве

1003 Plenary-How marine emissions contribute to atmospheric particles, with implications for climate

Dr. Rachel Chang Department of Physics and Atmospheric Science, Dalhousie University The exchange of energy and mass between the ocean and atmosphere occurs over many scales and in both directions, with implications for the physical and chemical state of both the atmosphere and ocean. This talk focuses on the how gases and particles emitted from the ocean can affect the aerosol particle population observed in the marine atmosphere, and the potential climate effects based on their impact on clouds, which can be quite extensive over the oceans. One region of the world that is extremely sensitive to cloud cover is the summer time Arctic, when sea-ice has retreated and the radiation is at its maximum. These conditions lead to ocean biological activity, which likely results in volatile organic compounds (VOC gases) being emitted into the atmosphere. Using atmospheric aerosol particle measurements from the Polar Environment Atmospheric Research Laboratory at Eureka, NU (80N, 86W) as well as the NETCARE (Network on Climate and Aerosols) cruises on board the CCGS Amundsen, we infer that these VOCs contribute to the frequent new particle formation and growth events observed in the Canadian Arctic Archipelago and that they can grow to sizes relevant for cloud droplet formation. Supporting model simulations show that this new source of aerosol particles can lead to 0.4 W/m2 of cooling in the Arctic summer through cloud-albedo radiative effects. Aerosol particles can also be emitted directly from the ocean into the atmosphere through sea spray, although the impact of ocean conditions on this flux remains uncertain. Recent results from laboratory experiments of sea spray aerosol generated from water sampled from the Halifax harbour show a distinct annual cycle. By linking this variability to the biological, chemical and physical properties of the harbour water, we highlight the potential impact of ocean properties on sea spray aerosols as well as their ability to impact climate through cloud formation. Together, this work shows that the emissions of marine gases and particles vary depending on the physical, chemical, and biological conditions of the ocean, impacting aerosol and cloud properties, and therefore climate.