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@ARTICLE{Steinhorst:45233,
      author       = {Steinhorst, H.-M. and Konopka, Paul and Günther, G. and
                      Müller, R.},
      title        = {{H}ow permeable is the edge of the {A}rctic vortex: {M}odel
                      studies of winter 1999-2000},
      journal      = {Journal of Geophysical Research},
      volume       = {110},
      issn         = {0148-0227},
      address      = {Washington, DC},
      publisher    = {Union},
      reportid     = {PreJuSER-45233},
      pages        = {D06105},
      year         = {2005},
      note         = {Record converted from VDB: 12.11.2012},
      abstract     = {The edge of the Arctic vortex constitutes a strong barrier
                      to transport; however, the extent of isolation of the vortex
                      air as a function of altitude and season is relatively
                      poorly quantified. In this study, by examining the transport
                      of midlatitude air parcels across the vortex edge into the
                      vortex, we analyze the permeability of the vortex edge. With
                      the three-dimensional version of CLaMS (Chemical Lagrangian
                      Model of the Stratosphere) we explore the dilution of the
                      vortex air due to mixing in winter 1999-2000. An artificial,
                      passive tracer was initialized on 1 December 1999 inside the
                      polar vortex with a value of $100\%$ and with a value of
                      zero outside the polar vortex. Using several different
                      definitions of the vortex edge, the resulting intrusions of
                      midlatitude air into the vortex show the same mean features.
                      This demonstrates that the diagnosed dilution does not
                      strongly depend on the details of the definition of the
                      vortex edge. At about the end of March 2000, the vertical
                      structure of the vortex consisted of well-isolated, pure
                      vortex layers around 500 K and 750 K, with some more diluted
                      layers in between and at the vortex bottom. The influence of
                      wave activity on the evolution of the intrusion layers is
                      studied. The divergence of the Eliassen-Palm flux shows such
                      a high variability during the whole period that it is not
                      possible to assess a direct causality of certain intrusion
                      layers and some specific patterns. Some characteristics of
                      the vortex edge, in particular the shape of the gradient of
                      potential vorticity (PV), can influence the dilution of the
                      vortex. In cases without a distinct maximum in the PV
                      gradient, the defined "vortex edge'' may vary substantially
                      from day to day. The comparison of some properties of the
                      vortex (wind speed, PV field, area of the vortex, the
                      maximum of the PV gradient) of undisturbed versus diluted
                      layers and the variation in time of the intrusions were
                      analyzed. All observed intrusions begin in conditions of
                      weak PV gradient, indicating that the value of the maximum
                      of the PV gradient may be used as a quantitative measure of
                      the permeability of the vortex edge.},
      keywords     = {J (WoSType)},
      cin          = {ICG-I},
      ddc          = {550},
      cid          = {I:(DE-Juel1)VDB47},
      pnm          = {Chemie und Dynamik der Geo-Biosphäre},
      pid          = {G:(DE-Juel1)FUEK257},
      shelfmark    = {Meteorology $\&$ Atmospheric Sciences},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000227874900003},
      doi          = {10.1029/2004JD005268},
      url          = {https://juser.fz-juelich.de/record/45233},
}