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@ARTICLE{Morgan:12645,
      author       = {Morgan, W.T. and Allan, J.D. and Bower, K.N. and Esselborn,
                      M. and Harris, B. and Henzing, J.S. and Highwood, E.J. and
                      Kiendler-Scharr, A. and McMeeking, G.R. and Mensah, A.A. and
                      Northway, M.J. and Osborne, S. and Williams, P.I. and
                      Krejci, R. and Coe, H.},
      title        = {{E}nhancement of the aerosol direct radiative effect by
                      semi-volatile aerosol components: airborne measurements in
                      {N}orth-{W}estern {E}urope},
      journal      = {Atmospheric chemistry and physics},
      volume       = {10},
      issn         = {1680-7316},
      address      = {Katlenburg-Lindau},
      publisher    = {EGU},
      reportid     = {PreJuSER-12645},
      pages        = {8151 - 8171},
      year         = {2010},
      note         = {This work is supported by Natural Environment Research
                      Council (NERC) ADIENT project NE/E011101/1, EUCAARI project
                      036833-2 and EUSAAR contract 026140. W. T. Morgan was
                      supported by NERC studentship NER/S/A/2006/14040 and a CASE
                      sponsorship from Aerodyne Research Inc. The NERC National
                      Centre for Atmospheric Science (NCAS) Facility for Ground
                      based Atmospheric Measurements (FGAM) supported the
                      maintenance of the cToF-AMS. NCAS also supported the
                      development of the data interpretation methods employed here
                      through its Composition Directorate. Thanks to the Cabauw
                      IMPACT team for provision of the radiosonde data. We thank
                      G. de Leeuw, the principal investigator at the AERONET
                      station at Cabauw for the provision of the AOD data and the
                      principal investigators at the other AERONET sites used. We
                      also thank F. Abicht, A. Minikin, T. Hamburger and A. Stohl
                      for their major contributions to the project. We thank the
                      FAAM, the Met Office, Avalon, DLR-Falcon and DirectFlight
                      personnel for their contributions to the campaign.},
      abstract     = {A case study of atmospheric aerosol measurements exploring
                      the impact of the vertical distribution of aerosol chemical
                      composition upon the radiative budget in North-Western
                      Europe is presented. Sub-micron aerosol chemical composition
                      was measured by an Aerodyne Aerosol Mass Spectrometer (AMS)
                      on both an airborne platform and a ground-based site at
                      Cabauw in the Netherlands. The examined period in May 2008
                      was characterised by enhanced pollution loadings in
                      North-Western Europe and was dominated by ammonium nitrate
                      and Organic Matter (OM). Both ammonium nitrate and OM were
                      observed to increase with altitude in the atmospheric
                      boundary layer. This is primarily attributed to partitioning
                      of semi-volatile gas phase species to the particle phase at
                      reduced temperature and enhanced relative humidity.
                      Increased ammonium nitrate concentrations in particular were
                      found to strongly increase the ambient scattering potential
                      of the aerosol burden, which was a consequence of the large
                      amount of associated water as well as the enhanced mass.
                      During particularly polluted conditions, increases in
                      aerosol optical depth of $50-100\%$ were estimated to occur
                      due to the observed increase in secondary aerosol mass and
                      associated water uptake. Furthermore, the single scattering
                      albedo was also shown to increase with height in the
                      boundary layer. These enhancements combined to increase the
                      negative direct aerosol radiative forcing by close to a
                      factor of two at the median percentile level. Such increases
                      have major ramifications for regional climate predictions as
                      semi-volatile components are often not included in aerosol
                      models.The results presented here provide an ideal
                      opportunity to test regional and global representations of
                      both the aerosol vertical distribution and subsequent
                      impacts in North-Western Europe. North-Western Europe can be
                      viewed as an analogue for the possible future air quality
                      over other polluted regions of the Northern Hemisphere,
                      where substantial reductions in sulphur dioxide emissions
                      have yet to occur. Anticipated reductions in sulphur dioxide
                      in polluted regions will result in an increase in the
                      availability of ammonia to form ammonium nitrate as opposed
                      to ammonium sulphate. This will be most important where
                      intensive agricultural practises occur. Our observations
                      over North-Western Europe, a region where sulphur dioxide
                      emissions have already been reduced, indicate that failure
                      to include the semi-volatile behaviour of ammonium nitrate
                      will result in significant errors in predicted aerosol
                      direct radiative forcing. Such errors will be particularly
                      significant on regional scales.},
      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:000281845800004},
      doi          = {10.5194/acp-10-8151-2010},
      url          = {https://juser.fz-juelich.de/record/12645},
}