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@PHDTHESIS{Plger:12688,
      author       = {Plöger, Felix},
      title        = {{I}mpact of different vertical transport representations on
                      simulating process in the tropical tropopause layer ({TTL})},
      volume       = {101},
      issn         = {1866-1793},
      school       = {Universität Wuppertal},
      type         = {Dr. (Univ.)},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {PreJuSER-12688},
      isbn         = {978-3-89336-695-8},
      series       = {Schriften des Forschungszentrums Jülich : Energie $\&$
                      Umwelt / Energy $\&$ Environment},
      pages        = {VI, 104 S.},
      year         = {2010},
      note         = {Record converted from JUWEL: 18.07.2013; Universität
                      Wuppertal, Diss., 2010},
      abstract     = {The chemical and dynamical processes in the tropical
                      tropopause layer (TTL) control the amount of radiatively
                      active species like water vapour and ozone in the
                      stratosphere, and hence turn out to be crucial for
                      atmospheric trends and climate change. Chemistry transport
                      models and chemistry climate models are suitable tools to
                      understand these processes. But model results are subject to
                      uncertainties arising from the parametrization of model
                      physics. In this thesis the sensitivity of model predictions
                      to the choice of the vertical transport representation will
                      be analysed. Therefore, backtrajectories are calculated in
                      the TTL, based on different diabatic and kinematic transport
                      representations using ERA-Interim and operational ECMWF
                      data. For diabatic transport on potential temperature
                      levels, the vertical velocity is deduced from the
                      ERA-Interim diabatic heat budget. For kinematic transport on
                      pressure levels, the vertical wind is used as vertical
                      velocity. It is found that all terms in the diabatic heat
                      budget are necessary to cause transport from the troposphere
                      to the stratosphere. In particular, clear-sky heating rates
                      alone miss very important processes. Many characteristics of
                      transport in the TTL turn out to depend very sensitively on
                      the choice of the vertical transport representation.
                      Timescales for tropical troposphere-tostratosphere transport
                      vary between one and three months, with respect to the
                      chosen representation. Moreover, for diabatic transport
                      ascent is found throughout the upper TTL, whereas for
                      kinematic transport regions of mean subsidence occur,
                      particularly above the maritime continent. To investigate
                      the sensitivity of simulated trace gas distributions in the
                      TTL to the transport representation, a conceptual approach
                      is presented to predict water vapour and ozone
                      concentrations from backtrajectories, based on instantaneous
                      freeze-drying and photochemical ozone production. It turns
                      out that ozone predictions and vertical dispersion of the
                      trajectories are highly correlated, rendering ozone an
                      interesting tracer for aspects of transport in the TTL where
                      water vapour is not sensitive. Consequently, dispersion and
                      mean upwelling have similar effects on ozone profiles, with
                      slower upwelling and larger dispersion both leading to
                      higher ozone concentrations. Analyses of tropical upwelling
                      based on mean transport characteristics (e.g., mean ascent
                      rates) and model validation have to take into account this
                      ambiguity. Predicted ozone concentrations for kinematic
                      transport are robustly higher than for diabatic transport,
                      due to larger trajectory dispersion caused by the larger
                      inhomogeneity in the kinematic vertical velocity field.
                      During the tropical SCOUT-O3 campaign, kinematic ozone
                      predictions show an extreme high bias compared to in-situ
                      observations. The high sensitivity of many characteristics
                      of transport to the choice of the transport representation,
                      demonstrates the need to better constrain transport in the
                      TTL. Consequently, estimates of exact numbers from models,
                      e.g., for timescales of transport, are not reliable and only
                      a range of values can be given. However, there are robust
                      features of tropical transport, not depending on the
                      transport representation, as for example, a significant
                      impact of monsoon driven horizontal in-mixing from the
                      extratropics on the composition of the TTL. In fact, the
                      annual cycle of ozone above the tropical tropopause is
                      attributed, at least in ‘ECMWF-world’, to in-mixing of
                      ozone-rich extratropical air during summer.},
      cin          = {IEK-7},
      ddc          = {500},
      cid          = {I:(DE-Juel1)IEK-7-20101013},
      pnm          = {Atmosphäre und Klima},
      pid          = {G:(DE-Juel1)FUEK491},
      typ          = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
      url          = {https://juser.fz-juelich.de/record/12688},
}