Studies of the Impact of Emission of Reactive Gases from Arctic Snowpacks and Sea Ice

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ABSTRACTShepsonOPP-0325361This project is motivated by two environmental observations: 1) snowpack and sea ice cover in the Arctic has been decreasing at alarming rates over the past couple decades, presumably related to climate change, and 2) air-snow interactions appear to have a significant impact on the composition of the lower atmosphere in snow covered environments. Recent field measurements in the Arctic have shown that sunlit snowpacks emit a variety of photolytically active species, such as bromine (Br2), bromine chloride (BrCl), nitrogen oxides (NOx), nitrous acid (HONO), formadehyde (HCHO), and (CH3CHO), into the atmosphere. These species have an impact on the abundance of ozone (O3) in the lower atmosphere; in the Arctic springtime, all the O3 in the lower atmosphere (up to ~ one km) can be removed from halogen atom reactions related to processes that occur at the snowpack/sea ice surface. Ozone can be destroyed within the sunlit snowpack, and that halogen-atom related chemistry results in the conversion of gas phase elemental mercury into potentially toxic particle phase mercury that then can be deposited on the Arctic Ocean surface. It is also likely that the halogen chemistry impacts the prevalence/severity of Arctic haze. Because O3 and particles have an impact on Earth's radiative balance, and O3 helps determine the oxidizing power of the atmosphere, and because snow cover is diminishing, prediction of the future state of the atmosphere, and how that relates to the Arctic, requires a quantitative understanding of air-snow interactions. Although it is known that photochemically important species are emitted from sunlit snowpacks into the lower atmosphere, the impacts of these processes on the atmosphere are not well defined. The Principal Investigator will develop methods to pursue these issues, through measurements of the vertical structure of the emitted chemical species above snowpacks and sea-ice in the Arctic. He will conduct vertical profile measurements of molecular halogens, some of their key atmospheric reaction products organohalogen compounds that may be emitted from the Arctic Ocean, and reactive carbonyl compounds, most specifically CH3CHO. For the halogenated compounds, these objectives will be pursued through measurements of vertical profiles from the surface to a few meters aloft. For CH3CHO, will develop the capability to conduct vertical profiles from the surface to ~1km, using an instrumented, battery powered small blimp. This sampling platform will provide the flexibility to sample from the near surface to one km, over any surface, such as open water, sea ice, and leads. They will conduct measurements during one month in the spring, 2005, in the area around Barrow, Alaska, and the local Arctic Ocean surface.Broader Impacts: Although the research community communicates effectively about environmental and atmospheric research in the Arctic, it is also important to responsibly educate the public about changes that are occurring in the Arctic. The Principal Investigator will involve the well-known and successful adventurer/author, Peter Lourie, as the first step to create a series of multimedia products aimed at educating school children and adults about the Arctic, and its people, in the context of global climate change and its impact on the Arctic. Mr. Lourie will travel to Barrow and interview researchers and the local Inupiat Eskimos, in preparation for production of books and videos. In addition, graduate and undergraduate education are central aspects of this effort.