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@ARTICLE{Saunois:22416,
      author       = {Saunois, M. and Emmons, L. and Lamarque, J.-F. and Tilmes,
                      S. and Wespes, C. and Thouret, V. and Schultz, M.},
      title        = {{I}mpact of sampling frequency in the analysis of
                      tropospheric ozone observations},
      journal      = {Atmospheric chemistry and physics},
      volume       = {12},
      issn         = {1680-7316},
      address      = {Katlenburg-Lindau},
      publisher    = {EGU},
      reportid     = {PreJuSER-22416},
      pages        = {6757 - 6773},
      year         = {2012},
      note         = {The National Center for Atmospheric Research is operated by
                      the University Corporation for Atmospheric Research under
                      the sponsorship of the National Science Foundation. The
                      authors acknowledge the strong support of the European
                      Commission, Airbus, and the airlines (Lufthansa, Austrian,
                      Air France) who carry free of charge the MOZAIC equipment
                      and perform the maintenance since 1994. MOZAIC is presently
                      funded by INSU-CNRS (France), Meteo-France, and
                      Forschungszentrum (FZJ, Julich, Germany). The MOZAIC data
                      base is supported by ETHER (CNES and INSU-CNRS). The authors
                      are grateful to all the agencies that provide ozone sonde
                      data to the World Ozone and Ultraviolet Radiation Data
                      Centre (WOUDC): German Weather Service - Meteorological
                      Observatory at Hohenpeissenberg and Lindenberg, the National
                      Meteorological Institute of the Netherlands, MeteoSwiss, the
                      Royal Meteorological Institute of Belgium and the Czech
                      HydroMeteorological Institute. The authors are grateful to
                      the two anonymous referees who helped to improve the
                      manuscript.},
      abstract     = {Measurements of ozone vertical profiles are valuable for
                      the evaluation of atmospheric chemistry models and
                      contribute to the understanding of the processes controlling
                      the distribution of tropospheric ozone. The longest record
                      of ozone vertical profiles is provided by ozone sondes,
                      which have a typical frequency of 4 to 12 profiles a month.
                      Here we quantify the uncertainty introduced by low frequency
                      sampling in the determination of means and trends. To do
                      this, the high frequency MOZAIC (Measurements of OZone,
                      water vapor, carbon monoxide and nitrogen oxides by
                      in-service AIrbus airCraft) profiles over airports, such as
                      Frankfurt, have been subsampled at two typical ozone sonde
                      frequencies of 4 and 12 profiles per month. We found the
                      lowest sampling uncertainty on seasonal means at 700 hPa
                      over Frankfurt, with around $5\%$ for a frequency of 12
                      profiles per month and $10\%$ for a 4 profile-a-month
                      frequency. However the uncertainty can reach up to 15 and
                      $29\%$ at the lowest altitude levels. As a consequence, the
                      sampling uncertainty at the lowest frequency could be higher
                      than the typical $10\%$ accuracy of the ozone sondes and
                      should be carefully considered for observation comparison
                      and model evaluation. We found that the $95\%$ confidence
                      limit on the seasonal mean derived from the subsample
                      created is similar to the sampling uncertainty and suggest
                      to use it as an estimate of the sampling uncertainty.
                      Similar results are found at six other Northern Hemisphere
                      sites. We show that the sampling substantially impacts on
                      the inter-annual variability and the trend derived over the
                      period 1998-2008 both in magnitude and in sign throughout
                      the troposphere. Also, a tropical case is discussed using
                      the MOZAIC profiles taken over Windhoek, Namibia between
                      2005 and 2008. For this site, we found that the sampling
                      uncertainty in the free troposphere is around 8 and $12\%$
                      at 12 and 4 profiles a month respectively.},
      keywords     = {J (WoSType)},
      cin          = {IEK-8},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IEK-8-20101013},
      pnm          = {Atmosphäre und Klima},
      pid          = {G:(DE-Juel1)FUEK491},
      shelfmark    = {Meteorology $\&$ Atmospheric Sciences},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000308287000005},
      doi          = {10.5194/acp-12-6757-2012},
      url          = {https://juser.fz-juelich.de/record/22416},
}