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@ARTICLE{Vmel:889802,
      author       = {Vömel, Holger and Smit, Herman G. J. and Tarasick, David
                      and Johnson, Bryan and Oltmans, Samuel J. and Selkirk, Henry
                      and Thompson, Anne M. and Stauffer, Ryan M. and Witte,
                      Jacquelyn C. and Davies, Jonathan and van Malderen, Roeland
                      and Morris, Gary A. and Nakano, Tatsumi and Stübi, Rene},
      title        = {{A} new method to correct the electrochemical concentration
                      cell ({ECC}) ozonesonde time response and its implications
                      for “background current” and pump efficiency},
      journal      = {Atmospheric measurement techniques},
      volume       = {13},
      number       = {10},
      issn         = {1867-8548},
      address      = {Katlenburg-Lindau},
      publisher    = {Copernicus},
      reportid     = {FZJ-2021-00415},
      pages        = {5667 - 5680},
      year         = {2020},
      abstract     = {The electrochemical concentration cell (ECC) ozonesonde has
                      been the main instrument for in situ profiling of ozone
                      worldwide; yet, some details of its operation, which
                      contribute to the ozone uncertainty budget, are not well
                      understood. Here, we investigate the time response of the
                      chemical reactions inside the ECC and how corrections can be
                      used to remove some systematic biases. The analysis is based
                      on the understanding that two reaction pathways involving
                      ozone occur inside the ECC that generate electrical currents
                      on two very different timescales. The main fast-reaction
                      pathway with a time constant of about 20 s is due the
                      conversion of iodide to molecular iodine and the generation
                      of two free electrons per ozone molecule. A secondary
                      slow-reaction pathway involving the buffer generates an
                      excess current of about $2 \%–10 \%$ with a time
                      constant of about 25 min. This excess current can be
                      interpreted as what has conventionally been considered the
                      “background current”. This contribution can be
                      calculated and removed from the measured current instead of
                      the background current. Here we provide an algorithm to
                      calculate and remove the contribution of the slow-reaction
                      pathway and to correct for the time lag of the fast-reaction
                      pathway.This processing algorithm has been applied to
                      ozonesonde profiles at Costa Rica and during the Central
                      Equatorial Pacific Experiment (CEPEX) as well as to
                      laboratory experiments evaluating the performance of ECC
                      ozonesondes. At Costa Rica, where a $1 \% KI,$ 1/10th
                      buffer solution is used, there is no change in the derived
                      total ozone column; however, in the upper troposphere and
                      lower stratosphere, average reported ozone concentrations
                      increase by up to $7 \%$ and above 30 km decrease by up
                      to $7 \%.$ During CEPEX, where a $1 \% KI,$
                      full-buffer solution was used, ozone concentrations are
                      increased mostly in the upper troposphere, with no change
                      near the top of the profile. In the laboratory measurements,
                      the processing algorithms have been applied to measurements
                      using the majority of current sensing solutions and using
                      only the stronger pump efficiency correction reported by
                      Johnson et al. (2002). This improves the accuracy of the ECC
                      sonde ozone profiles, especially for low ozone
                      concentrations or large ozone gradients and removes
                      systematic biases relative to the reference instruments.In
                      the surface layer, operational procedures prior to launch,
                      in particular the use of filters, influence how typical
                      gradients above the surface are detected. The correction
                      algorithm may report gradients that are steeper than
                      originally reported, but their uncertainty is strongly
                      influenced by the prelaunch procedures.},
      cin          = {IEK-8},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IEK-8-20101013},
      pnm          = {243 - Tropospheric trace substances and their
                      transformation processes (POF3-243)},
      pid          = {G:(DE-HGF)POF3-243},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000586659500001},
      doi          = {10.5194/amt-13-5667-2020},
      url          = {https://juser.fz-juelich.de/record/889802},
}