A multi-scale approach to elucidating the role of ice surfaces and synoptic meteorology in spring-time Arctic tropospheric ozone depletion events
Ground-level Arctic ozone depletion events have been studied since the mid-eighties. This process is generally attributed to heterogeneous reactions on saline ice surfaces under stable meteorological conditions. Bromine monoxide (a product of ozone depletion chemistry) has been routinely measured throughout the Arctic via satellite since the late 1990’s. It has been observed that high levels of BrO (believed to be in the troposphere) correspond well with first-year sea-ice, leading to the hypothesis that first-year sea-ice provides the heterogeneous surface upon which these depletion events can occur. However, there have been, to date, few ground-level measurements of BrO over the sea-ice, and certainly none for extended periods of time. Having continuous ground-level BrO/ozone measurements would prove useful in deciphering/verifying the satellite data. Further, the conditions required for depletion chemistry to occur are not known, thereby limiting our understanding of the chemical mechanism at play.^ Herein is presented research and instrumental/analysis developments to improve our collective understanding of the chemistry involved in these events. This involved studying the ice surface of snow crystals formed in a chamber in the lab to better understand the effects of impurities on the its surface structure, and its self-assembly mechanism. Second, a buoy-based instrument platform was developed to make autonomous measurements of ozone depletion related chemicals where the chemistry is believed to be occurring: on the sea-ice. As iodine potentially plays a role in depletion chemistry an ion chromatography method was developed to measure iodide levels in snow samples from the Arctic. Finally, to better define the meteorological conditions required for depletion chemistry to occur a comparison between satellite BrO column data and twenty meteorological variables was performed.^
Paul B. Shepson, Purdue University.
Atmospheric Chemistry|Chemistry, Analytical|Meteorology