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  • 1
    Electronic Resource
    Electronic Resource
    Tropospheric Ozone at High Latitudes in Clean and Polluted Air Masses, a Climatological Study (1997)
    Springer
    Journal of atmospheric chemistry 28 (1997), S. 111-123 
    Details
    ISSN: 1573-0662
    Keywords: surface ozone ; seasonal cycles ; NOx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Several years of continuous measurements of surfaceozone at Norwegian monitoring sites are studied in aclimatological way. The monitoring sites are at rurallocations extending from 58°N, a few hundredkilometers from the European continent and into theArctic at 79°N. The ozone observations are sorted intoclasses of integrated NOx emissions along 96 h backtrajectories. The average seasonal cycles of ozone areestimated for each class separately. The differencesindicate the change from the background air due toanthropogenic emissions. The average seasonal cycle ofozone in the cleanest air masses showed a maximum inspring and a minimum during summer and autumn at allsites, but the spring maximum was more pronounced atthe southernmost locations. Polluted air masses showedan ozone deficit during winter and a surplus duringsummer. The deviation from the background was clearlylinked to the integrated NOx emission along thetrajectories. In summer the calculations indicate thatthe number of ozone molecules formed per NOx moleculedrops with increasing emissions. The average seasonalcycle of ozone at Birkenes for different transportsectors indicate that the most pronounced ozoneformation takes place in air masses from E-Europe/Russia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005766612853
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  • 2
    Electronic Resource
    Electronic Resource
    European VOC Emission Estimates Evaluated by Measurements and Model Calculations (1997)
    Springer
    Journal of atmospheric chemistry 28 (1997), S. 173-193 
    Details
    ISSN: 1573-0662
    Keywords: volatile hydrocarbons ; observations and computer modelling ; tropospheric concentrations ; long range transport ; emission validation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Observations and model calculations of the concentration of hydrocarbonsat five Scandinavian rural sites during March–June 1993are reported.Decreasing concentrations from March to June are observedat all sites. The highest concentrations of hydrocarbons were found in air massescoming in from the southwest to southeast, indicating that long rangetransport fromcontinental Europe and the U.K. is important in pollution episodes. An episode of elevated concentrations of hydrocarbons observed at three of the sites in the middle of Marchis described and discussed in relation to the synoptic situation and thepresenceof other chemical compounds (NO2, PAN, total nitrate andozone).A Lagrangian numerical model is used to calculate the concentrations of theindividual hydrocarbons at the fivesites and comparison with observations is made.The calculated concentrations for nonmethane hydrocarbons with quite longchemicallifetimes agree well with the observations.For the sum of observed and calculated hydrocarbons the correlationcoefficientsare in the range of 0.65–0.88 for the five sitesand the ratio between calculated and measured concentrations was0.72–0.97, indicating thatthe European VOC emission inventory is quite well estimated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005859027649
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  • 3
    Electronic Resource
    Electronic Resource
    Gaseous and Particulate Oxidized and Reduced Nitrogen Species in the Atmospheric Boundary Layer in Scandinavia in Spring (1998)
    Springer
    Journal of atmospheric chemistry 30 (1998), S. 241-271 
    Details
    ISSN: 1573-0662
    Keywords: total nitrate ; total ammonium ; ozone ; filter pack ; denuder ; numerical modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Observations of the concentration of several nitrogen containing compounds at five rural Scandinavian sites during March–June 1993 are reported. Total nitrate (NO 3 - + HNO3) and total ammonium (NH 4 + + NH3) were measured by denuder and filter pack. In general the methods agree well. At all sites the particulate fraction dominated, with the largest fraction of NO 3 - and the lowest of NH 4 + at the sites which were closest to the emission sources. The fraction of NO 3 - of total nitrate increased with increasing NO2 concentrations, indicating that the nighttime conversion of NO2 to NO 3 - is an important route of formation for NO 3 - . A positive correlation was found between HNO3 and O3 in June at all sites, while no correlation was found early in the spring. Model calculations were made with a lagrangian boundary layer photooxidant model for the whole period, and compared to the measured concentrations. The calculated ratio between mean observed and modelled daily maximum concentrations of ozone over the measurement period were within +/−10% at all sites. The models ability to describe the daily ozone maximum concentration was satisfactory with an average deviation of 19–22% from the observed concentrations. HNO3 was underestimated by over 50% at all sites except the one closest to the emission sources. The correlation between modelled and observed concentrations was generally best for the sites with shortest transport distance from the sources of emission.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005901229253
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  • 4
    Electronic Resource
    Electronic Resource
    Boundary-layer ozone depletion as seen in the Norwegian Arctic in spring (1996)
    Springer
    Journal of atmospheric chemistry 23 (1996), S. 301-332 
    Details
    ISSN: 1573-0662
    Keywords: tropospheric ozone ; Arctic ; hydrocarbons ; halogens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Several years of measurements of ozone, hydrocarbons, sulphate and meteorological parameters from Spitsbergen in the Norwegian Arctic are presented. Most of the measurements were taken on the Zeppelin Mountain at an altitude of 474 m a.s.l. The focus is the episodes of ozone depletion in the lower troposphere in spring, which are studied in a climatological way. Episodes of very low ozone concentrations are a common feature on the Zeppelin Mountain in spring. The low ozone episodes were observed from late March to the beginning of June. When the effect of transport direction was subtracted, the frequenty of the low ozone episodes was found to peak in the beginning of May, possibly reflecting the seasonal cycle in the actual depletion process. Analyses based on trajectory calculations show that most of the episodes occurred when the air masses were transported from W-N. Ozone soundings show that the ozone depletion may extend from the surface and up to 3–4 km altitude. The episodes were associated with a cold boundary layer beneath a thermally stable layer, suppressing mixing with the free troposphere. The concentration of several individual hydrocarbons was much lower during episodes of low ozone than for the average conditions. The change in concentration ratio between the hydrocarbons was in qualitative agreement with oxidation of hydrocarbons by Br and Cl atoms rather than by OH radicals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00055158
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  • 5
    Electronic Resource
    Electronic Resource
    Carbonyls and nonmethane hydrocarbons at rural European sites from the mediterranean to the arctic (1996)
    Springer
    Journal of atmospheric chemistry 25 (1996), S. 33-66 
    Details
    ISSN: 1573-0662
    Keywords: hydrocarbons ; carbonyl compounds ; measurements ; European concentrations ; rural sites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Results of regular measurements during 1992–1995 of hydrocarbons and carbonyl compounds for a number of rural European monitoring sites are presented. The measurements are part of the EMEP programme for VOC measurements in Europe. In addition, several years of regular measurements are included from the Norwegian stations Birkenes at the south coast, and Zeppelin Mountain on Spitsbergen in the Arctic. The sampling frequency has been about twice per week throughout the years, implying that a substantial amount of measurement data are available. Almost all the chemical analyses have been performed by one laboratory, the EMEP Chemical Co-ordinating Centre located at NILU, which avoids problems of intercomparison and intercalibration among different laboratories. For the measured concentrations both seasonal and geographical variations are shown and discussed. The diurnal cycles of the hydrocarbon concentrations were studied in detail at one site, where the grab samples by EMEP where compared with a parallel continuous sampler, operated by EMPA, Switzerland. Hydrocarbons linked to natural gas and fuel evaporation become well mixed into the Arctic in the winter, whereas combustion products show a latitudinal gradient. The sum of oxygenated species constitutes about 5–15% of the sum of C2−C5 hydrocarbons in winter. In summer they are almost equal in magnitude, consistent with an increasing oxidation of hydrocarbons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00053285
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