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  • Springer  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Theoretical validation of ground-based microwave ozone observations (1994)
    Springer
    Annales geophysicae 12 (1994), S. 664-673 
    Details
    ISSN: 0992-7689
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Ground-based microwave measurements of the diurnal and seasonal variations of ozoneat 42±4.5 and 55±8 km are validated by comparing with results from a zero-dimensional photochemical model and a two-dimensional (2D) chemical/radiative/dynamical model, respectively. O3 diurnal amplitudes measured in Bordeaux are shown to be in agreement with theory to within 5%. For the seasonal analysis of O3 variation, at 42±4.5 km, the 2D model underestimates the yearly averaged ozone concentration compared with the measurements. A double maximum oscillation (\sim3.5%) is measured in Bordeaux with an extended maximum in September and a maximum in February, whilst the 2D model predicts only a single large maximum (17%) in August and a pronounced minimum in January. Evidence suggests that dynamical transport causes the winter O3 maximum by propagation of planetary waves, phenomena which are not explicitly reproduced by the 2D model. At 55±8 km, the modeled yearly averaged O3 concentration is in very good agreement with the measured yearly average. A strong annual oscillation is both measured and modeled with differences in the amplitude shown to be exclusively linked to temperature fields.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-994-0664-5
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  • 2
    Electronic Resource
    Electronic Resource
    How to evidence life on a distant planet (1994)
    Springer
    Astrophysics and space science 212 (1994), S. 327-333 
    Details
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Considering the future importance of the search for evidences of primitive life on a distant planet, we have revisited some points of the O2 and O3 detection criteria. The budget of free oxygen and organic carbon on Earth is studied. If one includes the organic carbon in sediments, it confirms that O2 is a very reactive gas whose massive presence in a telluric planet atmosphere implies a continuous production. Its detection would be a strong indication for photosynthetic activity, providing the planet is not in a runaway greenhouse phase. In principle, the direct detection of O2 could be possible in the visible flux of the planet at 760 nm (oxygen A-band) but it would be extremely difficult, considering the much larger flux from the star. The alternative search for the 9.7µm absorption of O3 may be easier as the contrast with the star is improved by 3 orders of magnitude. A simple atmospheric model confirms that the O3 column density is not a linear tracer of the atmospheric O2 content, as was found in the pioneer work by Paetzold (1962). However, the detection of a substantial O3 absorption (τ 〉 30%) would probably indicate, within the validity of this model, an O2 ground pressure larger than 10 mbar. The question is raised of whether this pressure is sufficient to indicate a photosynthetic origin of the oxygen. If the answer was positive, it would be an evenmore sensitive test of photosynthetic activity than the detection of the oxygen A-band. Further studies of these points are clearly needed before determining an observing strategy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00984536
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Vertical Profile of Night-Time Stratospheric OClO (1997)
    Springer
    Journal of atmospheric chemistry 26 (1997), S. 65-76 
    Details
    ISSN: 1573-0662
    Keywords: balloon-borne observations ; OClO ; vertical distribution ; stratosphere ; chemical models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The first night-time observation of the vertical profile of OClO wasperformed by the AMON balloon-borne spectrometer during the SESAME arcticcampaign, launched from Kiruna in northern Scandinavia. The flight, which tookplace inside the polar vortex on February 10, 1995, reveals mixing ratios of45±10 pptv at 20 km. These results are in excellent agreement with theREPROBUS 3D model simulations, which indicate that the observed OClOcorresponds to daytime ClO and BrO mixing ratios of 1.2 ppbv and 10 pptv,respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005757321761
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    Paper (German National Licenses)
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