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@PHDTHESIS{Lohse:256276,
      author       = {Lohse, Insa Mareike},
      title        = {{S}pektrale aktinische {F}lussdichten und
                      {P}hotolysefrequenzen – {U}ntersuchungen in der
                      atmosphärischen {G}renzschicht und der freien
                      {T}roposphäre},
      volume       = {285},
      school       = {Universität Köln},
      type         = {Dr.},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2015-06240},
      isbn         = {978-3-95806-086-9},
      series       = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
                      Umwelt / Energy $\&$ Environment},
      pages        = {VI, 111, VII-XXIII S.},
      year         = {2015},
      note         = {Universität Köln, Diss., 2015},
      abstract     = {Solar UV radiation is driving atmospheric photochemistry
                      because the photolysis of atmospheric trace gases yields
                      highly reactive atoms or radicals. Thus, trace gas
                      concentrations as well as accurate photolysis frequencies
                      are needed to understand atmospheric photochemical
                      processes. Especially under varying cloud conditions,
                      measurements can often not be replaced by radiative transfer
                      calculations with sufficient accuracy. In this work,
                      airborne measurements of the separate upwelling and
                      downwelling components of the actinic flux densities
                      (280–650 nm) were performed with CCD-spectroradiometers.
                      For accurate UV measurements a thorough treatment of stray
                      light was applied for the single monochromator based array
                      spectrometers. Moreover, the angular sensitivities of the
                      optical receivers were determined to analyze their influence
                      under various atmospheric conditions using radiative
                      transfer calculations of realistic atmospheric radiance
                      distributions. Corresponding correction factors in the range
                      of $5\%$ were derived. The overall performance was tested on
                      the ground by in-field comparisons with a
                      doublemonochromator reference system and found to have
                      maximum deviations of $7\%.$ Measurements of the spectral
                      actinic flux density were performed aboard Zeppelin NT in
                      the atmospheric boundary layer during the PEGASOS campaign
                      2012/13 over different parts of Europe. Moreover the
                      research aircraft HALO was used during the NARVAL campaign
                      2013/14 for measurements in the upper troposphere and the
                      lower stratosphere over the Atlantic Ocean. Typical Zeppelin
                      flight heights ranged from 100m to 900m and flights were
                      therefore always performed below possible cloud layers. Thus
                      the measurements were influenced by potentially overlaying
                      clouds and a small upwelling part of radiation. Radiative
                      transfer calculations of the downwelling component under the
                      assumption of clearsky conditions showed good agreement with
                      the maximum values of the measurements. The upwelling
                      component of the spectral actinic flux density was
                      unexpectedly greater than the model results. The reason for
                      this is unknown and requires further reasearch. Owing to the
                      typical flight heights of HALO in the range 8–14 km, the
                      measurements were affected by a high upwelling part of
                      radiation, especially when flying over clouds. The measured
                      downwelling components of j(O$^{1}$D) and j(NO$_{2}$) for
                      all flights and various cloud conditions showed only small
                      deviations of 4–5\% compared to clearsky model
                      calculations. Cloud-microphysical properties of underlying
                      clouds were retrieved for a certain time period of a
                      HALO-flight using spectral radiance measurements performed
                      by the Leipzig Institute for Meteorology and were used as
                      additional input parameters for radiative transfer
                      calculations of spectral actinic flux densities. The
                      deviations between model and measurements of up to 40\% for
                      the upwelling component can partly be attributed to the
                      geometrical receiving characteristics of the radiance optic.
                      Comparisons of measured photolysis frequencies and model
                      values of regional and global chemistry transport models
                      showed good agreements with small underestimations of
                      j(NO$_{2}$) by the models in the range of 20\%. For the
                      PEGASOS campaign the regional EURAD-IM model was found to
                      overestimate j(O$^{1}$D) significantly due to a low and
                      constant ozone column in the model. For the NARVAL campaign
                      good agreement for j(O$^{1}$D) with the global MOZART model,
                      that uses variable, modelled ozone columns, was obtained.},
      cin          = {IEK-8},
      cid          = {I:(DE-Juel1)IEK-8-20101013},
      pnm          = {243 - Tropospheric trace substances and their
                      transformation processes (POF3-243) / HITEC - Helmholtz
                      Interdisciplinary Doctoral Training in Energy and Climate
                      Research (HITEC) (HITEC-20170406)},
      pid          = {G:(DE-HGF)POF3-243 / G:(DE-Juel1)HITEC-20170406},
      typ          = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
      url          = {https://juser.fz-juelich.de/record/256276},
}