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@PHDTHESIS{Khordakova:910209,
      author       = {Khordakova, Dina},
      title        = {{I}mpact of severe convection on the water vapor mixing
                      ratio in the extra-tropical stratosphere},
      volume       = {586},
      school       = {Wuppertal},
      type         = {Dissertation},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2022-03686},
      isbn         = {978-3-95806-648-9},
      series       = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
                      Umwelt / Energy $\&$ Environment},
      pages        = {ii, 136},
      year         = {2022},
      note         = {Dissertation, Wuppertal, 2022},
      abstract     = {The emission of anthropogenic greenhouse gases leads to a
                      continuous increase in average global surface temperatures.
                      The radiative effect of the anthropogenic sources is
                      amplified by feedback processes, like the water vapor
                      feedback. The rapid change in climatic conditions is evident
                      not only in the mean of the relevant weather parameters, but
                      also in the severity and frequency of extreme events.
                      Extreme convective events in the troposphere not only have
                      immediate impacts on the surface, they can also influence
                      the dynamics and composition of the stratosphere. One major
                      impact is the moistening of the stratosphere by the
                      transport of tropospheric air masses by overshooting
                      convection and pyro-convection. This effect plays a crucial
                      role in climate feedback as small changes of water vapor
                      mixing ratios in the upper troposphere and lower
                      stratosphere (UTLS) have a large impact on the radiative
                      budget of the atmosphere and hence have an additional
                      positive feedback on the changing climate. In this thesis
                      four cases are investigated in which water vapor was
                      injected into the stratosphere. Two of them are cases of
                      convective overshooting and two are cases of
                      pyro-convection. In all of these cases, unusual values of
                      water vapor were measured in the stratosphere and a
                      persistent dynamical signature (potential vorticity anomaly)
                      was produced. For the convective case, the measurements were
                      made by the Cryogenic Frostpoint Hygrometer (CFH) which
                      requires Triflouromethane (R-23) as a cooling agent. Since
                      the year 2020, R-23 has not been acquirable in Europe.
                      Hence, an alternative cooling method for the instrument was
                      successfully explored and tested. The two cases of
                      convective overshooting were investigated on two consecutive
                      days in the European mid-latitudes in early summer of 2019.
                      Using balloon-borne instruments, measurements of
                      convectively injected water vapor in the stratosphere were
                      performed. The magnitude of the affected stratospheric water
                      vapor reached up to 12.1 ppmv with an estimated background
                      value of 5 ppmv. The corresponding water vapor values
                      measured by the Microwave Limb Sounder (MLS) satellite in
                      the lower stratosphere (LS) are lower than the in-situ
                      observations and the fifth generation of ECMWF atmospheric
                      global reanalysis (ERA5) reanalysis overestimated water
                      vapor mixing ratios.},
      cin          = {IEK-7},
      cid          = {I:(DE-Juel1)IEK-7-20101013},
      pnm          = {2112 - Climate Feedbacks (POF4-211)},
      pid          = {G:(DE-HGF)POF4-2112},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      url          = {https://juser.fz-juelich.de/record/910209},
}