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@ARTICLE{Kunz:17224,
      author       = {Kunz, A. and Pan, L.L. and Konopka, P. and Kinnison, D.E.
                      and Tilmes, S.},
      title        = {{C}hemical and dynamical discontinuity at the extratropical
                      tropopause based on {STRT}08 and {WACCM} analyses},
      journal      = {Journal of Geophysical Research},
      volume       = {116},
      issn         = {0148-0227},
      address      = {Washington, DC},
      publisher    = {Union},
      reportid     = {PreJuSER-17224},
      year         = {2011},
      note         = {A. Kunz is supported by the German Academy of Sciences
                      Leopoldina (LPDS 2009-25) and the visitor's program of the
                      Atmospheric Chemistry Division at the National Center for
                      Atmospheric Research (NCAR). NCAR is funded by the National
                      Science Foundation. Fruitful discussions with Rolf Muller,
                      Thomas Birner, and Tanya Peevey during the progress of this
                      work are particularly acknowledged. Thanks to Heini Wemli
                      and to two anonymous reviewers for their helpful comments.},
      abstract     = {Using isentropic trace gas gradients of O-3 and CO, the
                      discontinuity in the chemical composition of the upper
                      troposphere (UT) and lower stratosphere (LS) is examined on
                      middle world isentropes from 300 to 380 K. The analysis is a
                      follow-up study of the dynamical discontinuity as
                      represented by the potential vorticity (PV) gradient-based
                      tropopause, which is based on the product of isentropic PV
                      gradients and wind speed. Overall, there is fairly good
                      consistency between the chemical discontinuity in trace gas
                      distributions and the PV gradient-based tropopause. Trace
                      gas gradients at the PV gradient-based tropopause are
                      stronger in winter than in summer, revealing the seasonal
                      cycle of the tropopause transport barrier. The analysis of
                      the trace gas gradients also identifies atmospheric
                      transport pathways in the upper troposphere-lower
                      stratosphere (UTLS). Several regions where trace gas
                      gradients are found to be decoupled from the dynamical field
                      indicate preferred transport pathways between the UT and LS.
                      In particular, anomalous CO and O-3 gradients above eastern
                      Africa, eastern Asia, and the West Pacific are likely
                      related to convective transport, and anomalous O-3 gradients
                      over the North Atlantic and North Pacific are related to
                      isentropic transport connected to frequent wave breaking.
                      The results indicate that the PV gradient-based tropopause
                      definition provides a good identification of the dynamical
                      and chemical discontinuity and is therefore effective in
                      locating the physical boundary in the UTLS.},
      keywords     = {J (WoSType)},
      cin          = {IEK-7},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IEK-7-20101013},
      pnm          = {Atmosphäre und Klima},
      pid          = {G:(DE-Juel1)FUEK491},
      shelfmark    = {Meteorology $\&$ Atmospheric Sciences},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000298255700008},
      doi          = {10.1029/2011JD016686},
      url          = {https://juser.fz-juelich.de/record/17224},
}