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  • 1
    ISSN: 1420-9136
    Keywords: Electron paramagnetic resonance ; Free radicals ; Matrix isolation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract With some special adaptations the technique of matrix isolation followed by detection through electron paramagnetic resonance (EPR) can also be used for the measurement of atmospheric radical concentrations. A light weight cryogenic sampling device has been constructed. It uses condensation of atmospheric CO2 or H2O at 77 K for matrix formation and trapping of the radicals. The sampler has been flown on a balloon for stratospheric sampling. First data on stratospheric, HO2 and NO2 at 32 km altitude have been obtained on a flight on 8 August 1976 and will be reported.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 113 (1975), S. 389-402 
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary New measurements on the stratospheric distribution of H2, CH4, CO and N2O are presented and used to demonstrate the natural variability of the trace gas concentrations. The present CH4 and H2 measurements and data from older balloon flights are combined to give average vertical profiles. These profiles are compared with water vapor data from various authors to see if the vertical decrease in CH4 is matched by a corresponding increase in H2O. By comparing the average measured profiles to those predicted by a one-dimensional chemical model, profiles of the vertical eddy diffusion coefficientk z are deduced. Generally, a barrier in the low stratosphere and increasing transport in middle and upper stratosphere seem required to match theoretical and experimental profiles. The limitations of the calculatedk z are discussed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 116 (1978), S. 452-464 
    ISSN: 1420-9136
    Keywords: Trace gases ; Atmosphere ; Sources and Sinks ; Methane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract In 1972 average mixing ratio of methane in the troposphere was 1.41 ppm and 1.3 ppmv for the northern and southern hemisphere, respectively, which corresponds to a total amount of 4×1015 g of CH4 present in the atmosphere. Most is of recent biologic origin.14C analyses show that no more than 20 percent is released by fossil sources. The various ecosystems producing CH4 are discussed and the total annual production is estimated to lie between 5.5×1014 g/yr and 11×1014 g/yr. The corresponding turnover times for atmospheric CH4 range from 4 to 7 yrs. The destruction of CH4 takes place mainly in the troposphere, most probably through the reaction of CH4 + OH ↠ CH3 + H2O. About 10 percent of the CH4 is destroyed in the stratosphere. The CH4 cycle contributes on the order of 1 percent to the atmospheric carbon cycle.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 116 (1978), S. 545-553 
    ISSN: 1420-9136
    Keywords: Chlorofluoromethanes ; Stratospheric chlorine ; Trace gas observation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Available data on halogenated molecules in the stratosphere will be reviewed. Presently vertical profiles of CFCl3 and CF2Cl2 in the stratosphere exist to 50 km altitude. Only measurements in the lower stratosphere are reported for the other major halocarbons, CCl4 and CH3Cl. Profiles of the product species ClO, Cl, HCl, and HF exist to about 35 km. Comparison with theoretical profiles from 1-D models shows generally good agreement except for ClO where the earliest measured concentrations exceed the calculated ones considerably.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 116 (1978), S. 575-582 
    ISSN: 1420-9136
    Keywords: Chlorofluoromethanes ; Stratospheric chlorine ; Oceanographic tracers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Depth profiles of the chlorofluoromethanes (CFM), CFCl3 and CF2Cl2, have been obtained together with tritium profiles from water samples collected in the Norwegian Sea between surface and 2800 m depth. CFM analysis was performed by vacuum extraction of the dissolved gases from 500 ml samples of seawater and subsequent gaschromatographic measurement. The CFM concentration decreases with depth to about 10 percent of surface concentration at depths below 2000 m. The same behaviour is found for the tritium content. From a correlation of the CFM and tritium concentration the upper limit of the preindustrial atmospheric CFM levels can be estimated to ≤5 percent of the present day concentrations.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 106-108 (1973), S. 1352-1360 
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Stratospheric profiles of CH4 and H2 over eastern Texas have been derived up to 31 km altitude from air samples collected aboard a balloon and analyzed by gas chromatography. For H2, contamination during flight and measurement presented a problem which has been resolved only recently. The earlier profiles require corrections which are rather large for the highest altitudes. The three profiles indicate an increase of the H2 concentration in the lower stratosphere from about 0.5 p.p.m. per volume at the tropopause to about 0.8 p.p.m. at around 27 km altitude. Above that altitude the H2 concentration decreases again. An air sample collected between 44 and 62 km by a rocket-borne cryogenic sampler had an H2 concentration of 0.4 p.p.m. The five CH4 profiles showed a decrease in CH4 concentration with altitude generally with a steeper gradient directly above the tropopause and a weaker gradient at higher altitudes reaching 0.9 p.p.m. at 30 km altitude. The CH4 concentration in the rocket sample was 0.25 p.p.m., in good agreement with the gradient obtained from the balloon samples.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 66 (1979), S. 307-311 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Notes: Abstract Present methane concentrations in the northern troposphere average 1.65 ppm. Most CH4 is of recent biogenic origin. 14C analyses indicate that no more than 10% is released by fossil sources. The various CH4-producing ecosystems are described and the total annual production is estimated to lie between 5.9×1014 and 9.3×1014 g/y. CH4 is destroyed through photochemical oxidation mainly in the troposphere. In this process CH2O, H2, and CO are produced as intermediates. Tropospheric CH4 provides an important source of stratospheric water vapor.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of atmospheric chemistry 1 (1983), S. 27-51 
    ISSN: 1573-0662
    Keywords: Variance ; trace/gases ; stratosphere ; mixing length ; mixing surfaces
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The relative variances in stratospheric observations of longlived trace gases CH4, N2O, CF2Cl2, CFCl3 show large differences. These differences are greatly reduced when the local mean standard deviation is normalized to the local vertical gradient. This ratio, called ‘equivalent displacement height’ exhibits a characteristic vertical profile which is very similar for all the longlived trace gases, as well as for O3. With the help of this ratio, it is demonstrated that the variances are essentially due to natural causes, i.e., transport. Using the mixing length hypothesis a theoretical expression for the equivalent displacement height is derived. From it the meridional slope of the mixing surfaces and the mixing length can be calculated as function of the altitude. Additional information is obtained on the variance of that slope. The uncertainty of the measured mean trace gas profiles is defined.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of atmospheric chemistry 2 (1984), S. 117-124 
    ISSN: 1573-0662
    Keywords: Acetylene ; stratospheric profiles ; trace gas measurements ; stratosphere-troposphere exchange
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Stratospheric measurements of acetylene up to altitudes of 30 km are presented. The air samples were collected during three different balloon flights, two of them at 44°N, one at 32°N using balloon borne, liquid neon-cooled, cryosamplers. Their acetylene concentration was measured in the laboratory by flame ionisation gaschromatography. The different profiles at 32°N and 44°N are discussed with respect to possible vertical exchange processes and compared with published model calculations.
    Type of Medium: Electronic Resource
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  • 10
    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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