Research Objectives:
The phenomenon of sudden and complete boundary-layer (the part of the atmosphere closest to the surface) ozone loss has been observed at many northern high-latitude sites and more recently at sites in Antarctica. In the Arctic, ozone loss is, in part, related to pollution from the northern continents. Although the exact mechanisms remain uncertain, scientists have determined that there is also a link between active bromine (in part, from sea salt dissolved in surface snow) and low ozone on the large scale in the Arctic.
Considerably less is known about the mechanisms for sudden ozone losses in the Antarctic region. There is evidence for widespread bromine activation in coastal regions that seems to coincide with the average edge of the annual sea ice. It is important to study these events in Antarctica to help elucidate the role of pollution in low-ozone events.
This group undertook measurements of halogen oxides (ClO and BrO), ozone, and nitrogen oxides during the Winfly period (mid-August to October) of 2002 at McMurdo Station. The data, still being analyzed, revealed some quite surprising results that bear further investigation.
During this second research season at McMurdo, project team members will address the issues raised during the first study. Specifically, three questions will be asked:
+ How often is surface ozone at McMurdo affected by local pollution?
+ What reactive bromine compounds, in addition to BrO, are present and can we identify their source(s)?, and
+ How much is the snow surface directly impacting ozone?
The answer to each of these questions is important to achieving the broader goal of understanding the impact of natural halogen chemistry on boundary-layer ozone at high latitudes.
As sea-ice coverage changes in response to a changing climate, there may be attendant changes in the frequency and duration of boundary-layer ozone loss related to the availability of bromine gases derived from sea-salt. Gaining a more thorough understanding of the nature and mechanism(s) for boundary-layer ozone losses will enable better prediction of the impacts of future climate change on the chemical composition of the high latitude troposphere.
