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@ARTICLE{Schlosser:6107,
      author       = {Schlosser, E. and Brauers, T. and Dorn, H.-P. and Fuchs, H.
                      and Häseler, R. and Hofzumahaus, A. and Holland, F. and
                      Wahner, A. and Kanaya, Y. and Kajii, Y. and Miyamoto, K. and
                      Nishida, S. and Watanabe, K. and Yoshino, A. and Kubistin,
                      D. and Martinez, M. and Rudolf, N. and Harder, H. and
                      Berresheim, H. and Elste, T. and Plass-Dülmer, C. and
                      Stange, G. and Schurath, U.},
      title        = {{T}echnical {N}ote: {F}ormal blind intercomparison of {OH}
                      measurements: results from the international campaign
                      {HO}x{C}omp},
      journal      = {Atmospheric chemistry and physics},
      volume       = {9},
      issn         = {1680-7316},
      address      = {Katlenburg-Lindau},
      publisher    = {EGU},
      reportid     = {PreJuSER-6107},
      pages        = {7923 - 7948},
      year         = {2009},
      note         = {This work was supported by the EU FP-6 program EUROCHAMP
                      (grant no. RII3-CT-2004-505968) and ACCENT (Priority
                      1.1.6.3. Global Change and Ecosystems, grant no.
                      GOCE-CT-2004-505337).We thank F. Rohrer, R. Tillmann, and B.
                      Bohn for helpful discussions and supporting measurements,
                      and F. J. Johnen for assistance with the experiments.},
      abstract     = {Hydroxyl radicals (OH) are the major oxidizing species in
                      the troposphere. Because of their central importance,
                      absolute measurements of their concentrations are needed to
                      validate chemical mechanisms of atmospheric models. The
                      extremely low and highly variable concentrations in the
                      troposphere, however, make measurements of OH difficult.
                      Three techniques are currently used worldwide for
                      tropospheric observations of OH after about 30 years of
                      technical developments: Differential Optical Laser
                      Absorption Spectroscopy (DOAS), Laser-Induced Fluorescence
                      Spectroscopy (LIF), and Chemical Ionisation Mass
                      Spectrometry (CIMS). Even though many measurement campaigns
                      with OH data were published, the question of accuracy and
                      precision is still under discussion.Here, we report results
                      of the first formal, blind intercomparison of these
                      techniques. Six OH instruments (4 LIF, 1 CIMS, 1 DOAS)
                      participated successfully in the ground-based, international
                      HOxComp campaign carried out in Julich, Germany, in summer
                      2005. Comparisons were performed for three days in ambient
                      air (3 LIF, 1 CIMS) and for six days in the atmosphere
                      simulation chamber SAPHIR (3 LIF, 1 DOAS). All instruments
                      were found to measure tropospheric OH concentrations with
                      high sensitivity and good time resolution. The pairwise
                      correlations between different data sets were linear and
                      yielded high correlation coefficients (r(2)=0.75-0.96).
                      Excellent absolute agreement was observed for the
                      instruments at the SAPHIR chamber, yielding slopes between
                      1.01 and 1.13 in the linear regressions. In ambient air, the
                      slopes deviated from unity by factors of 1.06 to 1.69, which
                      can partly be explained by the stated instrumental
                      accuracies. In addition, sampling inhomogeneities and
                      calibration problems have apparently contributed to the
                      discrepancies. The absolute intercepts of the linear
                      regressions did not exceed 0.6x106 cm(-3), mostly being
                      insignificant and of minor importance for daytime
                      observations of OH. No relevant interferences with respect
                      to ozone, water vapour, NOx and peroxy radicals could be
                      detected. The HOxComp campaign has demonstrated that OH can
                      be measured reasonably well by current instruments, but also
                      that there is still room for improvement of calibrations.},
      keywords     = {J (WoSType)},
      cin          = {ICG-2},
      ddc          = {550},
      cid          = {I:(DE-Juel1)VDB791},
      pnm          = {Atmosphäre und Klima},
      pid          = {G:(DE-Juel1)FUEK406},
      shelfmark    = {Meteorology $\&$ Atmospheric Sciences},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000271240500017},
      url          = {https://juser.fz-juelich.de/record/6107},
}