Atmospheric Processes and Composition Group

Physical and Chemical Properties of Marine Fog

Fog and cloud droplets form on particles called cloud condensation nuclei (CCN), and of the numerous aerosol particles that exist in the atmosphere, only a small fraction of them can act as CCN and turn into droplets. Our work tries to understand how the properties of the underlying aerosol population affects fog events, in terms of fog droplet number, droplet size and fog lifetime. A second focus is on the ability of fog events to modify the chemical properties of the underlying aerosol population, in particular the organic fraction of the aerosol. Fog and clouds are an important part of the earth's radiation budget since they reflect incoming sunlight back into space. This work relies on custom-built sampling systems that will be used to sample fog at a coastal site in Nova Scotia.

Oceanic Contributions to Atmospheric Aerosol

Despite the fact that the ocean covers two-thirds of the earth's surface, our estimate of its contribution to atmospheric aerosol mass varies by two orders of magnitude. In addition, the discovery of a substantial organic aerosol fraction originating from the ocean has led to much speculation of its effect on cloud droplet formation. Our work will look at fog events that specifically originate from the ocean and study the ability of these particles to form droplets.

Arctic Aerosol Composition and Sources

Aerosol mass in the Arctic is dominated in the winter by transported pollution from Europe, Asia and North America, which builds up because the darkness causes the air to be stable. This phenomenon is known as Arctic Haze. In the summer time, the air is much cleaner and local sources, mostly marine if the conditions are clean, becomes much more important. Our work tries to understand the sources of Arctic aerosol by measuring the chemical composition at Eureka, Nunavut using the aerosol mass spectrometer that is part of the Polar Environment Atmospheric Research Laboratory. This long term record will be useful as summer sea-ice coverage decreases and industrial and shipping activities are likely to increase.