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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of atmospheric chemistry 22 (1995), S. 243-249 
    ISSN: 1573-0662
    Keywords: acetaldehyde ; background troposphere ; concentration distribution ; aircraft ; sampling technique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract A series of 72 measurements of the acetaldehyde (CH3CHO) mixing ratio were made in the lower troposphere during TROPOZ II. These measurements are the first ever made of the background level of this trace gas in the free troposphere. The data show a vertical decrease of the CH3CHO mixing ratio with increasing altitude and indicate higher CH3CHO concentrations in the Northern Hemisphere — in general agreement with a model-derived average CH3CHO distribution. Deviations of the observed CH3CHO mixing ratios from the modelled mean distribution are correlated with similar deviations in the corresponding HCHO mixing ratios.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of atmospheric chemistry 22 (1995), S. 251-269 
    ISSN: 1573-0662
    Keywords: formaldehyde ; background troposphere ; concentration distribution ; aircraft ; sampling technique ; methane oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract A series of 149 measurements of the HCHO mixing ratio were made between 0 and 10 km altitude and 70° N to 60° S latitude during TROPOZ II. The data show a vertical decrease of the HCHO mixing ratio with altitude at all latitudes and a broad latitudinal maximum in the HCHO mixing ratio between 30° N and 30° S at all altitudes. The measured mixing ratios of HCHO are considerably higher than those expected from CH4 oxidation alone, but agree broadly with the average latitude by altitude distribution of HCHO derived by a 2D model including emissions of C1–C7 hydrocarbons. A number of the regional scale deviations of the measured HCHO distribution from the average modelled one can be explained in terms of the local wind field.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of atmospheric chemistry 2 (1984), S. 191-202 
    ISSN: 1573-0662
    Keywords: Stratospheric photochemistry ; HO2 -, NO2 +in situ data ; vertical profiles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Vertical profiles of stratospheric HO2 and NO2 concentrations were determined using matrix isolation and ESR. Up to 10 different samples per flight were collected in situ by a balloon borne cryosampler. Free radicals and trace constituents which are condensable at 68 K are trapped in a polycristalline H2O or D2O matrix. After collection, the samples are stored at a temperature below 83 K until they are analysed in the laboratory by X-band ESR spectroscopy at 4 K. The HO2 and NO2 were identified and calibrated by comparison with standard samples collected in the laboratory under typical stratospheric sampling conditions. From several flights over Southern France (44°N) we obtained two profiles of the stratospheric NO2 mixing ratio. One, from 21 October 1982, agrees well with previous measurements. The other, from 8 October 1981, is lower by one order of magnitude. The few HO2 data obtained around 35 km altitude agree with previous measurements. An isolated measurement at 17 km altitude is one order of magnitude higher than the model predicted HO2 concentration.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of atmospheric chemistry 3 (1985), S. 341-361 
    ISSN: 1573-0662
    Keywords: Peroxyradicals ; NO2 ; in-situ measurement ; matrix isolation ; electron spin resonance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract A cryogenic system for the airborne and ground based sampling of ambient radicals by matrix isolation is described. The trapped radicals, e.g., NO2 and RO2, are analyzed by ESR. The technique has been improved, mainly by addition of water vapor to the sampled air, to yield a collection efficiency of (90±10)% and a lower detection limit of about 20 ppt, but it still does not distinguish between the different RO2. Careful calibration reduced the measurement error (1 σ) to ±10% for NO2 and ±15% for HO2. Two diurnal variations of RO2 and NO2 at ground level and vertical profiles in the lower troposphere are presented.
    Type of Medium: Electronic Resource
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