HR: 12:05h
AN: A12B-07    [Abstracts]
TI: Laboratory experiments concerning the growth and properties of frost flowers
AU: * Jacobi, H
EM: hwjacobi@awi-bremerhaven.de
AF: Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, Bremerhaven, 27570 Germany
AU: Lehmann, S
EM: slehmann@awi-bremerhaven.de
AF: Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, Bremerhaven, 27570 Germany
AB: Recently, frost flowers attracted a lot of scientific interest due to their specific properties. They constitute highly delicate structures, which grow on newly formed sea ice in both polar regions under certain meteorological conditions like a stable atmospheric boundary layer and low air temperatures. Frost flowers exhibit high specific surface areas and also contain high concentrations of sea salt components like chloride and bromide. Therefore, it has been suggested that they contribute to the release of reactive halogen compounds to the atmosphere, which in turn can cause the well-known tropospheric ozone depletion events. During such events surface ozone concentrations drop from regular values of 30 to 40 ppbV to values below 1 ppbV. Remote sensing data indicate a significant spatial correlation between the occurrence of frost flowers and high levels of tropospheric BrO concentrations, which is a reactive intermediate during the chemical destruction of ozone in the presence of reactive bromine. Furthermore, frost flowers are potentially important sources of sea salt aerosol in the coastal regions of Antarctica. Due to fractionation processes during the formation, frost flowers contain only depleted amounts of certain compounds compared to the major sea salt components. These specific chemical signatures have been used to identify aerosols generated from frost flowers. In contrast to the mounting evidence of the impact of frost flowers on tropospheric chemistry and aerosols in the polar regions, direct observations of the processes involving frost flowers are currently non-existent. Here, we report results of laboratory experiments with frost flowers. We established a laboratory set-up for the investigation of the growth of frost flowers. In addition, we analyzed physical and chemical properties of the laboratory-grown frost flowers as a function of the sea salt concentration of the water used for the formation of the new sea ice.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0312 Air/sea constituent fluxes (3339, 4504)
DE: 0365 Troposphere: composition and chemistry
DE: 0750 Sea ice (4540)
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005