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@PHDTHESIS{Knstler:878229,
      author       = {Künstler, Christopher},
      title        = {{M}easurements of {A}tmospheric {OH} and {HO}$_{2}$
                      {R}adicals by {L}aser-{I}nduced {F}luorescence on the {HALO}
                      {A}ircraft during the {OMO}-{ASIA} 2015 {C}ampaign},
      volume       = {495},
      school       = {Universität Köln},
      type         = {Dissertation},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2020-02698},
      isbn         = {978-3-95806-477-5},
      series       = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
                      Umwelt / Energy $\&$ Environment},
      pages        = {156 S.},
      year         = {2020},
      note         = {Universität Köln, Diss.,2020},
      abstract     = {The goal of this work was to investigate the chemistry of
                      atmospheric OH and HO$_{2}$ radicals in the upper
                      troposphere during the Asian summer monsoon period2015
                      within the Oxidation Mechanism Observation (OMO) campaign.
                      Concentrations of OH and HO$_{2}$ were measured by a
                      laser-induced fluorescence instrument (AirLIF) on the German
                      research aircraft HALO between the Mediterranean Sea and the
                      Maldives in the Indian Ocean. The measured data are compared
                      to theoretical model predictions in order to test the
                      understanding of atmospheric oxidation processes. For this
                      purpose the precedingly developed AirLIF instrument at
                      Forschungszentrum Jülich was thoroughly characterized in
                      the laboratory and different calibration concepts applied
                      and compared. The radical measurements during OMO were then
                      evaluated and a zero-dimensional chemical box-model
                      calculation for the expected OH and HO$_{2}$ radical
                      concentrations was tested against the measurement results.
                      For the radical measurements using the AirLIF instrument on
                      HALO, the ambient air is first sampled and decelerated by a
                      factor of 10 inside a shrouded inlet. The air is then
                      expanded into a measurement cell at low pressure inside the
                      aircraft, where OH is detected by laser excited
                      fluorescence. The OH and HO$_{2}$ channel of AirLIF needed
                      to be characterized for the flight conditions during OMO.
                      Different calibration concepts have been applied and
                      combined to determine the OH and HO$_{2}$ detection
                      sensitivities as a function of flight altitude, ambient
                      pressure and temperature. These include the well-established
                      ground-based calibrations between flights to track the
                      absolute sensitivities. The relative dependence with
                      altitude was measured in the laboratory using a newly
                      designed photochemical radical source which allows
                      calibration at reduced pressure to simulate ambient air
                      pressure at flight conditions. For the OH-channel as an
                      additional option an in-flight calibration unit inside the
                      shrouded inlet was used. It is however limited to below 10
                      km, because the radical production by the artificial
                      photolysis of ambient water vapour becomes too small. To
                      simulate the in-flight conditions, other research groups
                      have confided inusing different nozzle sizes to change the
                      mass-flow through the system ins-tead of varying ambient
                      pressure. As part of a consistency check, both methods have
                      been compared in detail and it is confirmed that they
                      essentially agree. However, discontinuities in the pressure
                      dependence of the OH [...]},
      cin          = {IEK-8},
      cid          = {I:(DE-Juel1)IEK-8-20101013},
      pnm          = {899 - ohne Topic (POF3-899)},
      pid          = {G:(DE-HGF)POF3-899},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      url          = {https://juser.fz-juelich.de/record/878229},
}