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  • Zenith sky observations of stratospheric O3, NO2, OClO and BrO  (1)
  • bromine  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Journal of atmospheric chemistry 30 (1998), S. 141-162 
    ISSN: 1573-0662
    Schlagwort(e): Zenith sky observations of stratospheric O3, NO2, OClO and BrO
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Geologie und Paläontologie
    Notizen: Abstract Zenith sky observations of O3, NO2, OClO and BrO are reported, which were performed at Kiruna (67.9°N, 21.1°E) within the SESAME winters 1993/1994 and 1994/95. For both winters large total amounts of OClO were observed inside the polar vortex at twilight, indicating the degree and the temporal variation of the halogen activation of the polar stratosphere. Occasionally OClO could also be observed outside the polar vortex, most likely due to export of halogen activated vortex air masses into the ambient stratosphere. BrO could also be detected in winter 1994/95, with the largest slant column amounts (5·1014/cm2) occuring in the polar vortex in mid-winter. Similar abundances of stratospheric BrO were observed at dusk and dawn, for both, air masses inside and outside the vortex. This observation is in reasonable agreement with previous studies on stratospheric BrO (observations and models) of Wahner et al. (1992), Arpag et al. (1994), Krug et al. (1996), and Lary et al. (1996a,b), but partly in disagreement with those of Solomon et al. (1989), Fish et al. (1995), and Sessler et al. (1996).
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Water, air & soil pollution 123 (2000), S. 229-244 
    ISSN: 1573-2932
    Schlagwort(e): bromine ; chlorine ; halogen species ; spectroscopy ; tropospheric chemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract While the role of reactive halogen species (e.g., Cl, Br) in the destruction of the stratospheric ozone layer is well known, up to now it was assumed that these tropospheric halogen events were confined to the polar regions during springtime. However, during the last few years, significant amounts of BrO and Cl-atoms were also found in the Arctic and Antarctic boundary layer. Recently, even higher BrO mixing ratios (up to 90 ppt) were detected by optical absorption spectroscopy (DOAS) in the Dead Sea basin during summer. In addition, evidence is accumulating that BrO (at levels around 1–2 ppt) is also occurring in the free troposphere (in polar regions as well as at mid- latitudes). In contrast to the strategosphere, where halogens are released from species which are very long lived in the troposphere, likely sources of boundary layer Br and Cl are oxidation of sea-salt halides, while precursors of free tropospheric BrO probably are short-lived organo-halogen species. In addition, it is well possible that boundary layer halogens, in particular bromine, may 'leak out' to the free troposphere and thus could have a regional or even more widespread effect. At the levels suggested by the available measurements, reactive halogen species have a profound effect on tropospheric chemistry: In the boundary layer during 'halogen events' ozone is usually completely lost within hours or days — the 'Polar Tropospheric Ozone Hole'. In the free troposphere the effective O3- losses due to halogens could be comparable to the known photochemical O3 destruction. Further interesting consequences include the increase of OH levels and (at low NOX) the decrease of the HO2/OH ratio in the free troposphere.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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