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  • 1
    Electronic Resource
    Electronic Resource
    First measurements of the vertical distribution of CCl4 and CH3CC13 in the stratosphere (1983)
    Springer
    Naturwissenschaften 70 (1983), S. 514-517 
    Details
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00394059
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  • 2
    Electronic Resource
    Electronic Resource
    Atmospheric chemistry of carbon disulphide (1983)
    Springer
    Journal of atmospheric chemistry 1 (1983), S. 65-86 
    Details
    ISSN: 1573-0662
    Keywords: Atmospheric oxidation ; carbon disulphide ; carbonyl sulphide ; sulphur cycle ; kinetic studies ; hydroxyl radical ; oxygen atom ; photolysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The oxidation of carbon disulphide has been studied under conditions which are likely to pertain in the atmosphere. The quantum yield for direct photo-oxidation of CS2 in air at 1 atm pressure, using near UV radiation was 0.012, with OCS as a major product. The rate coefficient (k 1) for the reaction of OH with CS2, was determined from measurements of OCS formation in the near UV photolysis of HONO−CS2−O2−N2 mixtures. k 1 was dependent on oxygen concentration rising from ≤4×10-14 cm3 molecule-1 s-1 at O2≤15 Torr to (2.0±1.0)×10-12 cm3 molecule-1 s-1 at 1 atm air and 300 K. Equimolar amounts of carbonyl sulphide and sulphur dioxide were the major reaction products. The concentration of carbon disulphide in the ambient atmosphere was measured and the concentration to be expected in the background atmosphere was estimated. Rate and concentration data were used to show that carbon disulphide oxidation represents a major source for atmospheric carbonyl sulphide. It can also serve as an alternate source for atmospheric sulphur dioxide in addition to that produced from hydrogen sulphide and dimethyl sulphide. A consideration of atmospheric concentrations and rate data for these trace sulphur gases suggests that the natural sulphur budget is much smaller than the yearly amounts of sulphur dioxide emitted from anthropogenic sources.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00113980
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  • 3
    Electronic Resource
    Electronic Resource
    The annual cycle of peroxides and ozone in marine air at Cape Grim, Tasmania (1996)
    Springer
    Journal of atmospheric chemistry 23 (1996), S. 221-252 
    Details
    ISSN: 1573-0662
    Keywords: photochemistry ; hydrogen peroxide ; ozone ; Cape Grim ; Tasmania
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The concentration of gas-phase peroxides has been measured almost continuously at the Cape Grim baseline station (41° S) over a period of 393 days (7702 h of on-line measurements) between February 1991 and March 1992. In unpolluted marine air a distinct seasonal cycle in concentration was evident, from a monthly mean value of〉1.4 ppbv in summer (December) to 〈0.2 ppbv in winter (July). In the summer months a distinct diurnal cycle in peroxides was also observed in clean marine air, with a daytime build-up in concentration and decay overnight. Both the seasonal and diurnal cycles of peroxides concentration were anticorrelated with ozone concentration, and were largely explicable using a simple photochemical box model of the marine boundary layer in which the central processes were daytime photolytic destruction of ozone, transfer of reactive oxygen into the peroxides under the low-NOx ambient conditions that favour self-reaction between peroxy radicals, and continuous heterogeneous removal of peroxides at the ocean surface. Additional factors affecting peroxides concentrations at intermediate timescales (days to a week) were a dependence on air mass origin, with air masses arriving at Cape Grim from higher latitudes having lower peroxides concentrations, a dependence on local wind speed, with higher peroxides concentrations at lower wind speeds, and a systematic decrease in peroxides concentration during periods of rainfall. Possible physical mechanisms for these synoptic scale dependencies are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00055155
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  • 4
    Electronic Resource
    Electronic Resource
    Processing of oxidised nitrogen compounds by passage through winter-time orographic cloud (1996)
    Springer
    Journal of atmospheric chemistry 24 (1996), S. 211-239 
    Details
    ISSN: 1573-0662
    Keywords: air pollution ; field study ; modelling ; atmospheric chemistry ; troposphere ; clouds ; nitrogen compounds ; NO x ; NO3 ; N2O5 ; NO3 - ; NO2 - ; HNO3 ; HNO2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Four case studies are described, from a three-site field experiment in October/November 1991 using the Great Dun Fell flow-through reactor hill cap cloud in rural Northern England. Measurements of total odd-nitrogen nitrogen oxides (NO y ) made on either side of the hill, before and after the air flowed through the cloud, showed that 10 to 50% of the NO y , called NO z , was neither NO nor NO2. This NO z failed to exhibit a diurnal variation and was often higher after passage through cloud than before. No evidence of conversion of NO z to NO3 - in cloud was found. A simple box model of gas-phase chemistry in air before it reached the cloud, including scavenging of NO3 and N2O5 by aerosol of surface area proportional to the NO2 mixing ratio, shows that NO3 and N2O5 may build up in the boundary layer by night only if stable stratification insulates the air from emissions of NO. This may explain the lack of evidence for N2O5 forming NO3 - in cloud under well-mixed conditions in 1991, in contrast with observations under stably stratified conditions during previous experiments when evidence of N2O5 was found. Inside the cloud, some variations in the calculated total atmospheric loading of HNO2 and the cloud liquid water content were related to each other. Also, indications of conversion of NO x to NO z were found. To explain these observations, scavenging of NO x and HNO2 by cloud droplets and/or aqueous-phase oxidation of NO2 - by nitrate radicals are considered. When cloud acidity was being produced by aqueous-phase oxidation of NO x or SO2, NO3 - which had entered the cloud as aerosol particles was liberated as HNO3 vapour. When no aqueous-phase production of acidity was occurring, the reverse, conversion of scavenged HNO3 to particulate NO3 -, was observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00210284
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  • 5
    Electronic Resource
    Electronic Resource
    Tropospheric Ozone Research (TOR) A Sub-Project of EUROTRAC (1997)
    Springer
    Journal of atmospheric chemistry 28 (1997), S. 1-9 
    Details
    ISSN: 1573-0662
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005807600764
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  • 6
    Electronic Resource
    Electronic Resource
    Studies of Oxidant Production at the Weybourne Atmospheric Observatory in Summer and Winter Conditions (1999)
    Springer
    Journal of atmospheric chemistry 33 (1999), S. 111-128 
    Details
    ISSN: 1573-0662
    Keywords: Weybourne Atmospheric Observatory ; ozone production ; peroxy radicls ; nitrogen oxides ; peroxy acetyl nitrate ; oxidant (O3+NO2)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Detailed studies have been made of the behaviour of gases and radicals involved in the production of oxidants at the Weybourne Atmospheric Observatory in both summertime and wintertime conditions. In June 1995 the range of meteorological conditions experienced varied such that ozone destruction was observed in clean northerly air flows reaching Weybourne down the North Sea from the Arctic, and ozone production was observed in varying degrees in air with different loadings of nitrogen oxides and other precursors. The transition point for ozone destruction to ozone production occurred at a nitric oxide concentration of the order of 50 pptv. Plumes of polluted air from various urban areas in the U.K. were experienced in the June campaign at Weybourne. Quantitative studies of ozone production in a plume from the Birmingham conurbation on 18 June 1995 showed that the measurement of ozone production agreed well with calculated production rates from the product of the nitric oxide and peroxy radical concentrations (r2=0.9). In wintertime conditions (October–November 1994) evidence was also found for oxidant production, defined as the sum of O3+NO2. At this time of year the peroxy radical concentrations (RO2) were much lower than observed in the summertime and the nitric oxide (NO) was much higher. There was still sufficient RO2 during the day, however, for a slow accumulation of oxidant. Confirmatory evidence for this comes from the diurnal co-variance of (O3+NO2) with PAN, an excellent tracer of tropospheric photochemistry. The same type of covariance occurs in summer between PAN and ozone. The results obtained in these series of measurements are pertinent to understanding the measures necessary to control production of regional photochemical air pollution, and to the production of ozone throughout the northern hemisphere in winter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005969204215
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  • 7
    Electronic Resource
    Electronic Resource
    The Weybourne Atmospheric Observatory (1999)
    Springer
    Journal of atmospheric chemistry 33 (1999), S. 107-110 
    Details
    ISSN: 1573-0662
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026428102821
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  • 8
    Electronic Resource
    Electronic Resource
    Tropospheric Box-Modelling and Analytical Studies of the Hydroxyl (OH) Radical and Related Species: Comparison with Observations (1999)
    Springer
    Journal of atmospheric chemistry 33 (1999), S. 183-214 
    Details
    ISSN: 1573-0662
    Keywords: hydroxyl radical ; troposphere ; modelling ; steady state
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Calculated and observed hydroxyl (OH) fields are presented. Calculated OH was obtained in three ways using (1) a photochemical box-model (2) a simple OH steady state approach and (3) a variant on (2) – the ‘multiple equation steady state’ approach which assumes steady state for OH, HO2 and RO2 and hence obtains three simultaneous, non linear, equations. All three methods used data collected in June 1995 during the Weybourne Atmospheric Observatory Summer Experiment (WAOSE'95). Julian Days 169, 178, 179 and 180 displayed especially good data capture and were consequently chosen for study. The two steady state methods are essentially driven purely by observations and derive OH from the ratio of the relevant source and sink terms. The box-model was constrained where possible to observations; remaining unmeasured volatile organic compounds (VOCs) were initialised to an arbitrary low value of 10 ppt. Agreement between theory and experiment was usually around 50% and often better than this value, especially on J169, though discrepancies of up to a factor of 3 were occasionally apparent. Despite the inherent scatter, neither the box-model nor the simple steady state method were found to consistently over-estimate OH (a common feature of many numerical approaches) although this did occur to a certain extent using the multiple equation steady state approach, probably due to breakdowns in the steady state approximation. More data spread was evident in the box-model approach compared with the other methods. An analysis of the major sources and sinks of OH is presented for the three methods of calculation. Calculated and observed peroxy radicals are also presented. Calculated peroxy radicals were generally lower than that observed at night yet higher, sometimes by up to a factor of 7, during the day. Possible explanations for this result are explored.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006009901180
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  • 9
    Electronic Resource
    Electronic Resource
    The Role of In Situ Photochemistry in the Control of Ozone during Spring at the Jungfraujoch (3,580 m asl) – Comparison of Model Results with Measurements (2000)
    Springer
    Journal of atmospheric chemistry 37 (2000), S. 1-27 
    Details
    ISSN: 1573-0662
    Keywords: photochemistry ; tropospheric ozone ; peroxy radicals ; Alps ; lower free troposphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract A photochemical box model has been used to model themeasured diurnal ozone cycle in spring at Jungfraujochin the Swiss Alps. The comparison of the modelleddiurnal ozone cycle with the mean measured diurnalozone cycle in spring, over the period 1988–1996,shows a good agreement both with regard to the shapeand amplitude. Ozone concentrations increase duringthe daytime and reach a maximum at about 16:00–17:00(GMT) in both the modelled and the mean observed ozonecycle, indicative of net ozone production during thedaytime at Jungfraujoch in spring. The agreement isbetter when the modelled ozone cycle is compared withthe mean measured diurnal cycle (1988–1996) filteredfor north-westerly winds 〉5 m/s (representative ofregional background conditions at Jungfraujoch). Inaddition to ozone, the modelled diurnal cycle of[HO2] + [CH3O2] also shows rather goodagreement with the mean diurnal cycle of the peroxyradicals measured during FREETEX '96, a FREETropopsheric Experiment at Jungfraujoch in April/May1996. Furthermore, this mean diurnal cycle of the sumof the peroxy radicals measured during FREETEX '96 isused to calculate, using steady-state expressions, therespective diurnal cycle of the OH radical. Thecomparison of the OH diurnal cycle, calculated fromthe peroxy radical measurements during FREETEX '96,with the modelled one, reveals also good agreement.The net ozone production rate during the day-time is0.27 ppbv h-1 from the model, and 0.13 ppbvh-1 from the observations during FREETEX '96. Theobservations and model results both suggest that thediurnal ozone variation in spring at Jungfraujoch isprimarily of photochemical origin. Furthermore, theobserved and modelled positive net ozone productionrates imply that tropospheric in situphotochemistry contributes significantly to theobserved high spring ozone values in the observedbroad spring-summer ozone maximum at Jungfraujoch.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006349926926
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  • 10
    Electronic Resource
    Electronic Resource
    Intercomparison of Formaldehyde Measurements in Clean and Polluted Atmospheres (2000)
    Springer
    Journal of atmospheric chemistry 37 (2000), S. 53-80 
    Details
    ISSN: 1573-0662
    Keywords: fluorescence ; spectroscopy ; tunable diode laser ; differential optical absorption ; intercomparison
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Three different techniques used tomeasure atmospheric formaldehyde were compared duringa field campaign carried out at a clean maritime siteon the West coast of Ireland. Two spectroscopictechniques Differential Optical AbsorptionSpectroscopy (DOAS) and Tunable Diode Laser AbsorptionSpectroscopy (TDLAS), together with a glass coil/Hantzschreaction/fluorescence technique, wereemployed for measurements of atmospheric formaldehydeof the order of a few hundred pptv. The betteragreement was observed between the fluorescence andDOAS instruments.Two DOAS instruments were compared to the glasscoil/Hantzsch reaction/fluorescence technique at asemi-polluted site on the North Norfolk coast, U.K.,where concentrations of formaldehyde were observed atlevels up to 4 ppbv. A very good agreement wasobserved between the two instruments.The glass coil/Hantzsch reaction/fluorescence and theTDLAS instruments were also deployed simultaneously inorder to measure indoor air inside a mobile laboratorylocated at the Imperial College Silwood Park site nearAscot, U.K. The doors of the mobile laboratory wereleft open in order to obtain the backgroundformaldehyde concentrations. Closing them afterwardsallowed us to observe the increase in concentrationsas a result of indoor emissions. The agreement betweenthe two instruments was outstanding (correlationcoefficient was 99%).The results from this study showed that of the fourinstruments included in this intercomparison the glasscoil/Hantzsch reaction/fluorescence technique provedthe most suitable for continuous measurements offormaldehyde in the background atmosphere.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006383520819
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