CACHE-CEFAC: Chemical Exchange and Feedbacks between the Atmosphere and Cryosphere

We will conduct year-round atmospheric chemistry measurements at Halley of key oxidants (OH, HO2, NO, O3, CO, Js), to study the role of the snowpack in determining the oxidant system. This will be in collaboration with Dr Greg Huey (http://www.eas.gatech.edu/people/faculty/huey.htm) from Georgia Institute of Technology. The Antarctic work will be carried out in the Clean Air sector Laboratory (CASLab)at Halley. Controlled laboratory experiments will be carried out at BAS HQ, using both natural and artificial snow, to study emissions triggered by light and how they vary with snow impurity content and mix. We will set up a network of surface ozone sensors in an area around the Antarctic coast, to measure the spatial extent of surface ozone depletion events; this will be done as part of the International Polar Year and include collaborators from other countries. Results from daily aerosol sampling at Halley will be combined with back trajectory analyses to assess the dominant source of sea salt aerosol to coastal Antarctica. Similar high resolution sampling will be carried out at an inland site. The results from these sampling programs will be used to generate parameterisations for sea salt that can be used in global models, while numerical models will also be used to explore the global implications of the emissions from, and losses over, snow and ice.