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@ARTICLE{Ziereis:906759,
      author       = {Ziereis, Helmut and Hoor, Peter and Grooß, Jens-Uwe and
                      Zahn, Andreas and Stratmann, Greta and Stock, Paul and
                      Lichtenstern, Michael and Krause, Jens and Bense, Vera and
                      Afchine, Armin and Rolf, Christian and Woiwode, Wolfgang and
                      Braun, Marleen and Ungermann, Jörn and Marsing, Andreas and
                      Voigt, Christiane and Engel, Andreas and Sinnhuber,
                      Björn-Martin and Oelhaf, Hermann},
      title        = {{R}edistribution of total reactive nitrogen in the
                      lowermost {A}rctic stratosphere during the cold winter
                      2015/2016},
      journal      = {Atmospheric chemistry and physics},
      volume       = {22},
      number       = {5},
      issn         = {1680-7316},
      address      = {Katlenburg-Lindau},
      publisher    = {EGU},
      reportid     = {FZJ-2022-01674},
      pages        = {3631 - 3654},
      year         = {2022},
      abstract     = {During winter 2015/2016, the Arctic stratosphere was
                      characterized by extraordinarily low temperatures in
                      connection with a very strong polar vortex and with the
                      occurrence of extensive polar stratospheric clouds. From
                      mid-December 2015 until mid-March 2016, the German research
                      aircraft HALO (High Altitude and Long-Range Research
                      Aircraft) was deployed to probe the lowermost stratosphere
                      in the Arctic region within the POLSTRACC (Polar
                      Stratosphere in a Changing Climate) mission. More than 20
                      flights have been conducted out of Kiruna, Sweden, and
                      Oberpfaffenhofen, Germany, covering the whole winter period.
                      Besides total reactive nitrogen (NOy), observations of
                      nitrous oxide, nitric acid, ozone, and water were used for
                      this study. Total reactive nitrogen and its partitioning
                      between the gas and particle phases are key parameters for
                      understanding processes controlling the ozone budget in the
                      polar winter stratosphere. The vertical redistribution of
                      total reactive nitrogen was evaluated by using
                      tracer–tracer correlations (NOy–N2O and NOy–O3). The
                      trace gases are well correlated as long as the NOy
                      distribution is controlled by its gas-phase production from
                      N2O. Deviations of the observed NOy from this correlation
                      indicate the influence of heterogeneous processes. In early
                      winter no such deviations have been observed. In January,
                      however, air masses with extensive nitrification were
                      encountered at altitudes between 12 and 15 km. The excess
                      NOy amounted to about 6 ppb. During several flights, along
                      with gas-phase nitrification, indications for extensive
                      occurrence of nitric acid containing particles at flight
                      altitude were found. These observations support the
                      assumption of sedimentation and subsequent evaporation of
                      nitric acid-containing particles, leading to redistribution
                      of total reactive nitrogen at lower altitudes. Remnants of
                      nitrified air masses have been observed until mid-March.
                      Between the end of February and mid-March, denitrified air
                      masses have also been observed in connection with high
                      potential temperatures. This indicates the downward
                      transport of air masses that have been denitrified during
                      the earlier winter phase. Using tracer–tracer
                      correlations, missing total reactive nitrogen was estimated
                      to amount to 6 ppb. Further, indications of transport and
                      mixing of these processed air masses outside the vortex have
                      been found, contributing to the chemical budget of the
                      winter lowermost stratosphere. Observations within
                      POLSTRACC, at the bottom of the vortex, reflect
                      heterogeneous processes from the overlying Arctic winter
                      stratosphere. The comparison of the observations with CLaMS
                      model simulations confirm and complete the picture arising
                      from the present measurements. The simulations confirm that
                      the ensemble of all observations is representative of the
                      vortex-wide vertical NOy redistribution.},
      cin          = {IEK-7},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IEK-7-20101013},
      pnm          = {2112 - Climate Feedbacks (POF4-211)},
      pid          = {G:(DE-HGF)POF4-2112},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000772232400001},
      doi          = {10.5194/acp-22-3631-2022},
      url          = {https://juser.fz-juelich.de/record/906759},
}