% IMPORTANT: The following is UTF-8 encoded.  This means that in the presence
% of non-ASCII characters, it will not work with BibTeX 0.99 or older.
% Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or
% “biber”.

@ARTICLE{Krause:856977,
      author       = {Krause, Jens and Hoor, Peter and Engel, Andreas and
                      Plöger, Felix and Grooß, Jens-Uwe and Bönisch, Harald and
                      Keber, Timo and Sinnhuber, Björn-Martin and Woiwode,
                      Wolfgang and Oelhaf, Hermann},
      title        = {{M}ixing and ageing in the polar lower stratosphere in
                      winter 2015–2016},
      journal      = {Atmospheric chemistry and physics},
      volume       = {18},
      number       = {8},
      issn         = {1680-7324},
      address      = {Katlenburg-Lindau},
      publisher    = {EGU},
      reportid     = {FZJ-2018-06266},
      pages        = {6057 - 6073},
      year         = {2018},
      abstract     = {We present data from winter 2015–2016, which were
                      measured during the POLSTRACC (The Polar Stratosphere in a
                      Changing Climate) aircraft campaign between December 2015
                      and March 2016 in the Arctic upper troposphere and lower
                      stratosphere (UTLS). The focus of this work is on the role
                      of transport and mixing between aged and potentially
                      chemically processed air masses from the stratosphere which
                      have midlatitude and low-latitude air mass fractions with
                      small transit times originating at the tropical lower
                      stratosphere. By combining measurements of CO, N2O and SF6
                      we estimate the evolution of the relative contributions of
                      transport and mixing to the UTLS composition over the course
                      of the winter.We find an increasing influence of aged
                      stratospheric air partly from the vortex as indicated by
                      decreasing N2O and SF6 values over the course of the winter
                      in the extratropical lower and lowermost stratosphere
                      between Θ = 360K and Θ = 410K over the North
                      Atlantic and the European Arctic. Surprisingly we also found
                      a mean increase in CO of (3.00±1.64)ppbV from January to
                      March relative to N2O in the lower stratosphere. We show
                      that this increase in CO is consistent with an increased
                      mixing of tropospheric air as part of the fast transport
                      mechanism in the lower stratosphere surf zone. The analysed
                      air masses were partly affected by air masses which
                      originated at the tropical tropopause and were
                      quasi-horizontally mixed into higher latitudes.This increase
                      in the tropospheric air fraction partly compensates for
                      ageing of the UTLS due to the diabatic descent of air masses
                      from the vortex by horizontally mixed,
                      tropospheric-influenced air masses. This is consistent with
                      simulated age spectra from the Chemical Lagrangian Model of
                      the Stratosphere (CLaMS), which show a respective fractional
                      increase in tropospheric air with transit times under 6
                      months and a simultaneous increase in aged air from upper
                      stratospheric and vortex regions with transit times longer
                      than 2 years.We thus conclude that the lowermost
                      stratosphere in winter 2015–2016 was affected by aged air
                      from the upper stratosphere and vortex region. These air
                      masses were significantly affected by increased mixing from
                      the lower latitudes, which led to a simultaneous increase in
                      the fraction of young air in the lowermost Arctic
                      stratosphere by $6\%$ from January to March 2016.},
      cin          = {IEK-7},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IEK-7-20101013},
      pnm          = {244 - Composition and dynamics of the upper troposphere and
                      middle atmosphere (POF3-244)},
      pid          = {G:(DE-HGF)POF3-244},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000431293300002},
      doi          = {10.5194/acp-18-6057-2018},
      url          = {https://juser.fz-juelich.de/record/856977},
}