Atmospheric Chemistry and Climate by ewghwehws

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									          A multi-model
          analysis of the
    tropospheric ozone budget
 David Stevenson1, F.J. Dentener2, M.G. Schultz3, K. Ellingsen4, T.P.C. van Noije5, O. Wild6,
    G. Zeng7, M. Amann8, C.S. Atherton9, N. Bell10, D.J. Bergmann9, I. Bey11, T. Butler12,
      J. Cofala8, W.J. Collins13, R.G. Derwent14, R.M. Doherty1, J. Drevet11, H.J. Eskes5,
A.M. Fiore15, M. Gauss4, D.A. Hauglustaine16, L.W. Horowitz15, I.S.A. Isaksen4, M.C. Krol2, J.-
          F. Lamarque17, M.G. Lawrence12, V. Montanaro18, J.-F. Müller19, G. Pitari18,
 M.J. Prather20, J.A. Pyle7, S. Rast3, J.M. Rodriguez21, M.G. Sanderson13, N.H. Savage7, D.T.
                      Shindell10, S.E. Strahan21, K. Sudo6, and S. Szopa16
   1. University of Edinburgh, School of GeoSciences, Edinburgh, United Kingdom. 2. Joint Research Centre, Institute for Environment and Sustainability, Ispra, Italy.
                       3. Max Planck Institute for Meteorology, Hamburg, Germany. 4. University of Oslo, Department of Geosciences, Oslo, Norway.
                            5. Royal Netherlands Meteorological Institute (KNMI), Atmospheric Composition Research, De Bilt, the Netherlands.
       6. Frontier Research Center for Global Change, JAMSTEC, Yokohama, Japan. 7. University of Cambridge, Centre of Atmospheric Science, United Kingdom.
  8. IIASA, International Institute for Applied Systems Analysis, Laxenburg, Austria. 9. Lawrence Livermore National Laboratory, Atmos. Science Div., Livermore, USA.
                    10. NASA-Goddard Institute for Space Studies, New York, USA. 11. Ecole Polytechnique Fédéral de Lausanne (EPFL), Switzerland.
                      12. Max Planck Institute for Chemistry, Mainz, Germany. 13. Met Office, Exeter, United Kingdom. 14. rdscientific, Newbury, UK.
                        15. NOAA GFDL, Princeton, NJ, USA. 16. Laboratoire des Sciences du Climat et de l'Environnement, Gif-sur-Yvette, France.
                                      17. National Center of Atmospheric Research, Atmospheric Chemistry Division, Boulder, CO, USA.
                                                         18. Università L'Aquila, Dipartimento di Fisica, L'Aquila, Italy.
                                                        19. Belgian Institute for Space Aeronomy, Brussels, Belgium.
                                                 20. Department of Earth System Science, University of California, Irvine, USA
                                         21. Goddard Earth Science & Technology Center (GEST), Maryland, Washington, DC, USA.
  Tropospheric ozone budget
• Ozone is an important greenhouse gas and air pollutant

• Ozone budget and lifetime crucial for:
   –   Long-range transport
   –   Global Warming Potentials
   –   Oxidising capacity
   –   Climate-Chemistry (radiative forcing and feedbacks)

• Previous intercomparisons (e.g. IPCC TAR literature survey) of
  modelled tropospheric ozone budget hampered by:
   – Definition of PO3 and LO3
   – Definition of troposphere
   – Differences in emissions

• What we really want to understand are differences due to model
  formulation (chemistry, convection, resolution, mixing,
  boundary conditions…)
  Defining the O3 or Ox budget
                                        Stratospheric input
                    HO2NO2




        PAN               NO2                  O3                  L:
                                            O(3P) O(1D)
dep                                                              O3 + HO2
                                                               O3 + OH
            N2O5                            O3 deposition     O(1D) + H2O
                                                              O3 + alkenes
                NO3             dep
                                                                + other net
                                      P: NO + RO2               loss terms
Some studies             HNO3
use wider definition;
should make only                             NO
minor difference
      Different model chemical schemes – potential source of differences
   ACCENT Intercomparison
• Prescribed anthropogenic emissions
  – but modellers used their own natural emissions, so
    still some emissions uncertainty
• Defined O3 budget terms
  – but some modellers used their own definitions,
    specific to chemical scheme
  – requested 3D monthly mean P and L
  – also O3 deposition; inferred stratospheric input
• Defined tropopause O3=150 ppbv
  – centralised analysis
    20 Models supplied O3 budgets
•   CHASER_CTM                   •   MOZ2-GFDL
•   CHASER_GCM                   •   MOZART4
•   FRSGC/UCI                    •   MOZECH
•   GEOS-CHEM                    •   MOZECH2
•   GMI/CCM3                     •   STOCHEM-HadAM3
•   GMI/DAO                      •   STOCHEM-HadGEM
•   GMI/GISS                     •   TM4
•   LLNL-IMPACT                  •   TM5
•   LMDz/INCA-CTM                •   ULAQ
•   LMDz/INCA-GCM                •   UM_CAM
CTMs driven by analyses                     CTMs coupled to GCMs
                    CTMs driven by GCM output
                                 Year 2000 Tropospheric O3 budget                                S1 Tropospheric O3 budget

          7500
          7000                                                                                                                                                                                            P   L        P-L   D      Sinf
          6500
          6000
          5500
          5000
          4500
TgO3/yr




          4000
          3500
          3000
          2500
          2000
          1500
          1000
           500
             0
          -500




                                                                                                                                         MOZECH
                                                   GEOS-CHEM




                                                                                        gmigis
                              CHASER_GCM
                 CHASER_CTM




                                                                                                                                                                          STOCHEM_HadGEM
                                           FRSGC




                                                                                                                                                  NCAR
                                                                                                                 LMDzINCA




                                                                                                                                                                                           TM4

                                                                                                                                                                                                 TM5
                                                                                                                            LMDzINCAc




                                                                                                                                                                                                       ULAQ
                                                                               GMIDAO




                                                                                                                                                         STOCHEM_HadAM3
                                                               GFDL




                                                                                                   LLNL-IMPACT




                                                                                                                                                                                                              UM_CAM
                                                                      GMICCM




                                                                                                                                                                                                                                 Mean

                                                                                                                                                                                                                                           Median
     Tg(O3)/yr                                                  P                                L                                      D                                 Sinf                         B/Tg(O3)
                                                                                                                                                                                                                                   t/days
ACCENT                                                     5100                         4670                                    1000                                      550                             340                              22
IPCC TAR                                                   3420                         3470                                            770                               770                             300                              24
 Zonal Annual Mean Ozone chemical production




                        Ozone
                     chemical
                    production
 Relatively high
 values throughmainly reflects
              Differences at poles
             NOx distributions
whole troposphere


                        Relatively low
                          values in
                         tropical UT
Zonal Annual Mean Ozone chemical destruction




             Ozone
            chemical
           destruction
         mainly reflects
         H2O distribution
          (also O3 distribution)
Zonal Annual Mean Ozone net chemical production
Surface level O3 Net Chemical Production
Multi-model ensemble mean
      ozone P, L, NCP




                       Ship NOx



        = 0.997    Surface
Multi-model ensemble mean
      ozone P, L, NCP




        = 0.975
Multi-model ensemble mean
      ozone P, L, NCP




        = 0.930
Multi-model ensemble mean
      ozone P, L, NCP




        = 0.870
Multi-model ensemble mean
      ozone P, L, NCP




        = 0.792      Mid-trop
                   net destruction
Multi-model ensemble mean
      ozone P, L, NCP




        = 0.700      Mid-trop
                   net destruction
Multi-model ensemble mean
      ozone P, L, NCP




        = 0.600      Mid-trop
                   net destruction
Multi-model ensemble mean
      ozone P, L, NCP




        = 0.505
Multi-model ensemble mean
      ozone P, L, NCP




        = 0.422
Multi-model ensemble mean
      ozone P, L, NCP




                     Upper-trop
        = 0.355   net production
                      lightning
Multi-model ensemble mean
      ozone P, L, NCP




                     Upper-trop
        = 0.300   net production
                      lightning
Multi-model ensemble mean
      ozone P, L, NCP




                     Upper-trop
        = 0.250   net production
                      lightning
Multi-model ensemble mean
      ozone P, L, NCP




                     Upper-trop
        = 0.200   net production
                      lightning
Multi-model ensemble mean
      ozone P, L, NCP




                     Upper-trop
        = 0.150   net production
                      lightning
Multi-model ensemble mean
      ozone P, L, NCP




                     Upper-trop
        = 0.099   net production
                      lightning
                     Global O3 budget terms
                                                           Results for a
                                                           single model,
                            Higher burden                  several scenarios
                              goes with
O3 lifetime / days



                            longer lifetime
                                                             Colours signify
                                                             different models



                      MFR


                                                               Ensemble mean
                                         A2
                                                               model (offset)
                                      As emissions rise,
                                      burden increases,
                                         lifetime falls        Climate change
                                                               shortens lifetime
                                                               but burden can
                                                               rise/fall
                                    O3 burden / Tg(O3)
                  Conclusions
• First well-constrained analysis of several model’s ozone
  budgets, with consistent definitions of budget terms,
  tropospheric domain, and anthropogenic emissions
• Broadly consistent gross features
• Production reflects NOx distribution
• Destruction reflects H2O (and O3) distribution
• Some inter-model differences in lightning
  NOx/convection; isoprene; H2O; polewards transport; BL
• Quite large differences compared to IPCC TAR
   – NOx and isoprene emissions
   – Stratospheric input
• Deposition also crucial; most of the O3 budget is in BL
           Further information
• Dentener et al., in press, Env. Sci. Tech.
   – Overview of intercomparison
• Stevenson et al., in press, JGR
   – Tropospheric O3 and CH4
• Van Noije et al., in press, ACPD
   – NO2 columns, modelled & GOME
• Shindell et al., submitted, JGR
   – CO, modelled & MOPITT
• Dentener et al., submitted, GBC
   – Deposition of N and S
• Ellingsen et al., in prep.
   – Surface O3 air quality
• +probably more
• dstevens@staffmail.ed.ac.uk

								
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