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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 285 (1980), S. 312-314 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Nitrous acid was detected and monitored using the long path differential UV absorption technique described by Platt et al6. The optical system in the present experiments used a 0.3m McPherson spectrograph with a 600 grooves mm-1 grating blazed at 500 nm (giving a dispersion of 5.3nm per mm). A ...
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillan Magazines Ltd.
    Nature 395 (1998), S. 486-490 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Reactive bromine species contribute significantly to the destruction of ozone in the polar stratosphere. Reactive halogen compounds can have a strong effect not only on the chemistry of the stratosphere but also on that of the underlying troposphere. For example, severe ozone depletion events ...
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 348 (1990), S. 147-149 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The chemical processes we discuss here are initiated by reaction of NO2 with ozone to form NO3 radicals NO2 + O3 -〉 NO3 + O2 (1) Depending on the trace-gas composition of the air mass, several reactions can generate peroxy radicals (see Table 1). For instance, they are generated by the ...
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillian Magazines Ltd.
    Nature 423 (2003), S. 273-276 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The emission of volcanic gases usually precedes eruptive activity, providing both a warning signal and an indication of the nature of the lava soon to be erupted. Additionally, volcanic emissions are a significant source of gases and particles to the atmosphere, influencing tropospheric and ...
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Annales geophysicae 17 (1999), S. 1457-1462 
    ISSN: 0992-7689
    Keywords: Atmospheric composition and structure (aerosols and particles, cloud physics and chemistry) ; Meteorology and atmospheric dynamics (mesoscale meteorology)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Polar stratospheric clouds (PSCs) are often observed in the Kiruna region in northern Sweden, east of the Scandinavian mountain range, during wintertime. PSC occurrence can be detected by ground-based optical instruments. Most of these require clear tropospheric weather. By applying the zenith-sky colour index technique, which works under most weather conditions, the data availability can be extended. The observations suggest that PSC events, especially of type II (water PSCs) may indeed more common than predicted by synoptic models, which is expected because of the frequent presence of mountain-induced leewaves. However, it will be of importance to increase the density of independent observations.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-0662
    Keywords: Zenith sky observations of stratospheric O3, NO2, OClO and BrO
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: 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).
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-0662
    Keywords: Isotopic composition of H2O ; water vapour transport ; stratospheric-tropospheric exchange
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Simultaneous measurements of the three rare isotopes Deuterium (D), Tritium (T), and Oxygen-18 (18O) in water vapour were made for the first time in the vicinity of the northern hemisphere tropopause. In contrast to expectation, high D/H and 18O/16O ratios, but relatively low T/H ratios, were found within the lowermost stratosphere. Since water vapour in the low-latitude upper troposphere shows a similar isotopic signature, we conclude that in the mid-latitudes considerable amounts of tropospheric water vapour are injected into the lowermost stratosphere, probably resulting in a hydration of the lower stratosphere. In addition, T can serve as tracer for precipitation of water containing stratospheric aerosol particles, because the T/H ratio in stratospheric water vapour is orders of magnitude higher than in the upper troposphere. Thus, even a small contribution of water of stratospheric origin should be detectable in the tropopause region. In our measurements performed in the Arctic we did not find isotopic evidence for sedimentation of PSC particles down to the tropopause. This may be caused by the low spatial and temporal coverage of our observations; however, it may also be due to the much weaker wintertime dehydration of the Arctic vortex compared to the Antarctic.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of atmospheric chemistry 32 (1999), S. 101-120 
    ISSN: 1573-0662
    Keywords: stratospheric NO2 ; latitudinal cross section
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract During a series of flights in the winters 1991/92 to 1994/95 total stratospheric NO2 was measured by means of the DOAS (Differential Optical Absorption Spectroscopy) technique on board a C160 (Transall) aircraft. In an area covering 60°W to 60°E, and 16°N to 86°N, the total stratospheric NO2 was observed to vary markedly with latitude and season (winter and spring). In the mid-winter Arctic vortex extremely low total stratospheric NO2 (〈 3.1014/cm2) was always found, generally larger amounts of NO2 occurred outside the vortex in winter and towards the spring both inside and outside the vortex. This behaviour of stratospheric NO2 can be explained by the denoxification of the wintertime polar stratosphere. Ambient to the vortex in mid-winter however, ‘sudden’ increases of total stratospheric NO2 by about a factor of 3 were observed. These sudden increases in stratospheric NO2 coincide with a change in the wavenumber 2 of the geopotential height at 60°N, which indicates that most likely the events are caused by planetary waves efficiently transporting air masses rich in NOx from lower to higher latitudes. The monitoring of stratospheric NO2, during latitudinal traverses ranging from the Arctic (80°N) to the Subtropics (18°N) in spring also unexpectedly showed a large variability in total stratospheric NO2 at mid-latitudes. Since photochemistry almost certainly can be excluded, it is proposed that the observed variability may be due to the planetary wave activity of the stratospheric surf zone, known to dynamically connect the tropical and the polar stratosphere.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-0662
    Keywords: tropospheric ozone ; atmospheric aerosol particles ; halogen chemistry ; Arctic regions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The halogen ions Br- and Cl- together with NO3 -, SO4 =, MSA- (methane sulfonate), Na+ and NH4 + were analysed by ion chromatography in extracts of more than 800 aerosol cellulose filter samples taken at Ny Ålesund, Svalbard (79°N, 12°E) in spring 1996 (March 27 - May 16) within the European Union project ARCTOC (Arctic Tropospheric Ozone Chemistry). Anticorrelated variations between f-Br (filterable bromine, i.e. water soluble bromine species that can be collected by aerosol filters) and ozone within the arctic troposphere were evaluated at a resolution of 1 or 2 hours for periods with depleted ozone and 4 hours at normal ozone. A mean f-Br concentration of 11 ng m-3 (0.14 nmol m-3) was observed for the whole campaign, while maximum concentrations of 80 ng m-3 (1 nmol m-3) were detected during two total O3-depletion events (O3 drop to mixing ratios below the detection limit of 〈 2 ppb). Anticorrelation between f-Br and O3 was also seen during minor O3-depletion episodes (sudden drop in O3 by at least 10 ppb, but O3 still exceeding the detection limit) and even for ozone variations near its background level (40-50 ppb). A time lag of about 10 hours between the change of ozone and of f-Br concentrations could only be found during a total ozone depletion event, when f-Br reached its maximum values several hours after ozone was totally destroyed. Bromine oxide (BrO) concentrations, measured by DOAS (Differential Optical Absorption Spectroscopy), and f-Br showed a coincident variability during almost the entire campaign (except in the case of total O3-loss). Frequently enhanced anthropogenic nitrate and sulphate concentrations were observed during O3-depletion periods. At O3 concentrations 〈 10 ppb sulphate and nitrate exceed their typical mean level by 54% and 77%, respectively. This may indicate a possible connection between acidity and halogen release.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1573-0662
    Keywords: OH-radicals ; troposphere ; long path absorption spectroscopy ; sensitivity study ; formaldehyde ; measurements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Using long path UV absorption spectroscopy we have measured OH concentrations close to the earth's surface. The OH values observed at two locations in Germany during 1980 through 1983 range from 0.7×106 to 3.2×106 cm-3. Simultaneously we measured the concentrations of O3, H2O, NO, NO2, CH4, CO, and the light non methane hydrocarbons. We also determined the photolysis rates of O3 and NO2. This allows calculations of OH using a zero dimensional time depdendent model. The modelled OH concentrations significantly exceed the measured values for low NO x concentrations. It is argued that additional, so far unidentified. HO x loss reactions must be responsible for that discrepancy.
    Type of Medium: Electronic Resource
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