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@ARTICLE{Gautrois:31206,
      author       = {Gautrois, M. and Brauers, T. and Koppmann, R. and Rohrer,
                      F. and Stein, O. and Rudolph, J.},
      title        = {{S}easonal variability and trends of volatile organic
                      compounds in the lower polar troposphere},
      journal      = {Journal of Geophysical Research},
      volume       = {108},
      issn         = {0148-0227},
      address      = {Washington, DC},
      publisher    = {Union},
      reportid     = {PreJuSER-31206},
      pages        = {13},
      year         = {2003},
      note         = {Record converted from VDB: 12.11.2012},
      abstract     = {[1] Measurements of the atmospheric mixing ratios of 10
                      nonmethane hydrocarbons (NMHC) and four halocarbons (methyl
                      chloride, dichloromethane, trichloroethene, and
                      tetrachloroethene) were conducted between January 1989 and
                      July 1996 at Alert (Canadian Arctic, 82degrees27'N,
                      62degrees31'W). About 270 canister samples were analyzed
                      covering the 7-year period with an average frequency of
                      about one sample every 9 days. The mixing ratios of these
                      volatile organic compounds (VOC) exhibit considerable
                      variability, which can partly be described by systematic
                      seasonal dependencies. The highest mixing ratios were always
                      observed during winter. During spring, the mixing ratios
                      decrease for some compounds to values near the detection
                      limit. The amplitudes of the seasonal variability, the time
                      of the occurrence of the maxima, and the relative steepness
                      of the temporal gradients show a systematic dependence on OH
                      reactivity. The steepest relative decrease is less than
                      $1\%$ d(-1) for methyl chloride, increasing to about $4\%$
                      d(-1) for highly reactive VOC. Similarly, the highest
                      relative increase rates vary between $0.5\%$ d(-1) for VOC
                      with low reactivity to $4\%$ d(-1) for reactive VOC. With
                      the exception of ethyne, toluene, and methyl chloride the
                      concentrations of all measured VOC decrease during the
                      studied period, although this decrease is not always
                      statistically significant. In general, the largest changes
                      were found for the most reactive VOC, although the seemingly
                      random overall variability observed for these compounds
                      results in substantial uncertainties. For the less reactive
                      VOC (ethane, benzene, and propane) the average relative
                      annual decrease rate is in the range of a few percent per
                      year. Dichloromethane and tetrachloroethene showed a
                      decrease of 4 and $14\%$ yr(-1), respectively. The average
                      decrease rate for the other alkanes is in the range of some
                      $10\%$ yr(-1), indicating a substantial change of emission
                      rates during this period. A likely explanation is a
                      reduction in VOC emissions in the area of the former Soviet
                      Union, most likely Siberia, as a consequence of the recent
                      major economic changes in this region. The measurements were
                      compared with the results of chemical transport models'
                      simulations using the Emission Database for Global
                      Atmospheric Research NMHC emission inventory. Although the
                      model captures most of the main features of the shapes of
                      the seasonal cycles of the NMHC, the results clearly show
                      that model estimates are consistently too low compared to
                      the observations. Most likely this is the consequence of an
                      underestimate of the NMHC emission rates in the emission
                      inventory.},
      keywords     = {J (WoSType)},
      cin          = {ICG-II},
      ddc          = {550},
      cid          = {I:(DE-Juel1)VDB48},
      pnm          = {Chemie und Dynamik der Geo-Biosphäre},
      pid          = {G:(DE-Juel1)FUEK257},
      shelfmark    = {Meteorology $\&$ Atmospheric Sciences},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000184339200002},
      doi          = {10.1029/2002JD002765},
      url          = {https://juser.fz-juelich.de/record/31206},
}