% IMPORTANT: The following is UTF-8 encoded.  This means that in the presence
% of non-ASCII characters, it will not work with BibTeX 0.99 or older.
% Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or
% “biber”.

@ARTICLE{Law:13759,
      author       = {Law, K.S. and Fierli, F. and Cairo, F. and Schlager, H. and
                      Borrmann, S. and Ravegnani, F. and Real, E. and Kunkel, D.
                      and Schiller, C. and Streibel, M. and Ulanovsky, A. and
                      Viciani, S. and Volk, C.M.},
      title        = {{A}ir mass origins influencing {TTL} chemical composition
                      over {W}est {A}frica during 2006 summer monsoon},
      journal      = {Atmospheric chemistry and physics},
      volume       = {10},
      issn         = {1680-7316},
      address      = {Katlenburg-Lindau},
      publisher    = {EGU},
      reportid     = {PreJuSER-13759},
      pages        = {10753 - 10770},
      year         = {2010},
      note         = {The M55-Geophysica SCOUT-AMMA campaign in West Africa was
                      funded by the Geophysica EEIG, French CNRS-INSU/CNES and
                      European Community sixth framework integrated projects
                      SCOUT-O3 (505390-GOCE-CT-2004) and AMMA-EU. The authors also
                      wish to acknowledge the contribution and help of Burkinabe
                      institutes and scientists in the organisation and execution
                      of the M55 aircraft campaign. Based on a French initiative,
                      AMMA was built by an international scientific group and
                      funded by a large number of agencies, especially from
                      France, UK, US and Africa. It has been the beneficiary of a
                      major financial contribution from the European Community's
                      Sixth Framework Research Programme. Detailed information on
                      scientific coordination and funding is available on the AMMA
                      International web site http://www.amma-international.org.
                      Scientists from ISAC-CNR acknowledge partial support from
                      Dipartimento Terra ed Ambiente, National Research Council.},
      abstract     = {Trace gas and aerosol data collected in the tropical
                      tropopause layer (TTL) between 12-18.5 km by the M55
                      Geophysica aircraft as part of the SCOUT-AMMA campaign over
                      West Africa during the summer monsoon in August 2006 have
                      been analysed in terms of their air mass origins. Analysis
                      of domain filling back trajectories arriving over West
                      Africa, and in the specific region of the flights, showed
                      that the M55 flights were generally representative of air
                      masses arriving over West Africa during the first 2 weeks of
                      August, 2006. Air originating from the mid-latitude lower
                      stratosphere was under-sampled (in the mid-upper TTL) whilst
                      air masses uplifted from central Africa (into the lower TTL)
                      were over-sampled in the latter part of the campaign.
                      Signatures of recent (previous 10 days) origins were
                      superimposed on the large-scale westward flow over West
                      Africa. In the lower TTL, air masses were impacted by recent
                      local deep convection over Africa at the level of main
                      convective outflow (350 K, 200 hPa) and on certain days up
                      to 370 K (100 hPa). Estimates of the fraction of air masses
                      influenced by local convection vary from 10 to $50\%$
                      depending on the method applied and from day to day during
                      the campaign. The analysis shows that flights on 7, 8 and 11
                      August were more influenced by local convection than on 4
                      and 13 August allowing separation of trace gas and aerosol
                      measurements into "convective" and "non-convective" flights.
                      Strong signatures, particularly in species with short
                      lifetimes (relative to CO2) like CO, NO and fine-mode
                      aerosols were seen during flights most influenced by
                      convection up to 350-365 K. Observed profiles were also
                      constantly perturbed by uplift (as high as $39\%)$ of air
                      masses from the mid to lower troposphere over Asia, India,
                      and oceanic regions resulting in import of clean oceanic
                      (e.g. O-3-poor) or polluted air masses from Asia (high O-3,
                      CO, CO2) into West Africa. Thus, recent uplift of CO2 over
                      Asia may contribute to the observed positive CO2 gradients
                      in the TTL over West Africa. This suggests a more
                      significant fraction of younger air masses in the TTL and
                      needs to taken into consideration in derivations of mean age
                      of air. Transport of air masses from the mid-latitude lower
                      stratosphere had an impact from the mid-TTL upwards
                      $(20-40\%$ above 370 K) during the campaign period importing
                      air masses with high O-3 and NOy. Ozone profiles show a less
                      pronounced lower TTL minimum than observed previously by
                      regular ozonesondes at other tropical locations.
                      Concentrations are less than 100 ppbv in the lower TTL and
                      vertical gradients less steep than in the upper TTL. The air
                      mass origin analysis and simulations of in-situ net
                      photochemical O-3 production, initialised with observations,
                      suggest that the lower TTL is significantly impacted by
                      uplift of O-3 precursors (over Africa and Asia) leading to
                      positive production rates (up to 2 ppbv per day) in the
                      lower and mid TTL even at moderate NOx levels. Photochemical
                      O-3 production increases with higher NOx and H2O in air
                      masses with O-3 less than 150 ppbv.},
      keywords     = {J (WoSType)},
      cin          = {IEK-7},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IEK-7-20101013},
      pnm          = {Atmosphäre und Klima},
      pid          = {G:(DE-Juel1)FUEK491},
      shelfmark    = {Meteorology $\&$ Atmospheric Sciences},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000284759500004},
      doi          = {10.5194/acp-10-10753-2010},
      url          = {https://juser.fz-juelich.de/record/13759},
}