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@ARTICLE{Stein:155942,
      author       = {Stein, O. and Schultz, Martin and Bouarar, I. and Clark, H.
                      and Huijnen, V. and Gaudel, A. and George, M. and Clerbaux,
                      C.},
      title        = {{O}n the wintertime low bias of {N}orthern {H}emisphere
                      carbon monoxide found in global model simulations},
      journal      = {Atmospheric chemistry and physics},
      volume       = {14},
      number       = {17},
      issn         = {1680-7324},
      address      = {Katlenburg-Lindau},
      publisher    = {EGU},
      reportid     = {FZJ-2014-04865},
      pages        = {9295 - 9316},
      year         = {2014},
      abstract     = {Despite the developments in the global modelling of
                      chemistry and of the parameterization of the physical
                      processes, carbon monoxide (CO) concentrations remain
                      underestimated during Northern Hemisphere (NH) winter by
                      most state-of-the-art chemistry transport models. The
                      consequential model bias can in principle originate from
                      either an underestimation of CO sources or an overestimation
                      of its sinks. We address both the role of surface sources
                      and sinks with a series of MOZART (Model for Ozone And
                      Related Tracers) model sensitivity studies for the year 2008
                      and compare our results to observational data from
                      ground-based stations, satellite observations, and vertical
                      profiles from measurements on passenger aircraft. In our
                      base case simulation using MACCity (Monitoring Atmospheric
                      Composition and Climate project) anthropogenic emissions,
                      the near-surface CO mixing ratios are underestimated in the
                      Northern Hemisphere by more than 20 ppb from December to
                      April, with the largest bias of up to 75 ppb over Europe in
                      January. An increase in global biomass burning or biogenic
                      emissions of CO or volatile organic compounds (VOCs) is not
                      able to reduce the annual course of the model bias and
                      yields concentrations over the Southern Hemisphere which are
                      too high. Raising global annual anthropogenic emissions with
                      a simple scaling factor results in overestimations of
                      surface mixing ratios in most regions all year round.
                      Instead, our results indicate that anthropogenic CO and,
                      possibly, VOC emissions in the MACCity inventory are too low
                      for the industrialized countries only during winter and
                      spring. Reasonable agreement with observations can only be
                      achieved if the CO emissions are adjusted seasonally with
                      regionally varying scaling factors. A part of the model bias
                      could also be eliminated by exchanging the original
                      resistance-type dry deposition scheme with a
                      parameterization for CO uptake by oxidation from soil
                      bacteria and microbes, which reduces the boreal winter dry
                      deposition fluxes. The best match to surface observations,
                      satellite retrievals, and aircraft observations was achieved
                      when the modified dry deposition scheme was combined with
                      increased wintertime road traffic emissions over Europe and
                      North America (factors up to 4.5 and 2, respectively). One
                      reason for the apparent underestimation of emissions may be
                      an exaggerated downward trend in the Representative
                      Concentration Pathway (RCP) 8.5 scenario in these regions
                      between 2000 and 2010, as this scenario was used to
                      extrapolate the MACCity emissions from their base year 2000.
                      This factor is potentially amplified by a lack of knowledge
                      about the seasonality of emissions. A methane lifetime of
                      9.7 yr for our basic model and 9.8 yr for the optimized
                      simulation agrees well with current estimates of global OH,
                      but we cannot fully exclude a potential effect from errors
                      in the geographical and seasonal distribution of OH
                      concentrations on the modelled CO.},
      cin          = {IEK-8 / JSC},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IEK-8-20101013 / I:(DE-Juel1)JSC-20090406},
      pnm          = {233 - Trace gas and aerosol processes in the troposphere
                      (POF2-233) / 411 - Computational Science and Mathematical
                      Methods (POF2-411)},
      pid          = {G:(DE-HGF)POF2-233 / G:(DE-HGF)POF2-411},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000341992000029},
      doi          = {10.5194/acp-14-9295-2014},
      url          = {https://juser.fz-juelich.de/record/155942},
}