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Centre for Atmospheric Science University of Cambridge

Centre for Atmospheric Science University of Cambridge. AMMA-UK: Work Package 5 Centre for Atmospheric Science University of Cambridge Glenn Carver Andrew Robinson Nicola Warwick (pretending to be John Pyle and Neil Harris). Work packages.

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Centre for Atmospheric Science University of Cambridge

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  1. Centrefor Atmospheric ScienceUniversity of Cambridge AMMA-UK: Work Package 5Centre for Atmospheric ScienceUniversity of CambridgeGlenn CarverAndrew RobinsonNicola Warwick(pretending to be John Pyle and Neil Harris)

  2. Work packages WP5.1 Use observations of the convective outflows in the TTL regions to analyse the chemical and dynamical processes occurring in such outflows. WP5.2 Use modelling techniques to assess global transport and impacts of species from WAM & estimate impacts on lower stratosphere. OWP5 TTL chemistry balloons. Two stratospheric balloons deployed during SOP2 to gain observations of the TTL region in the vicinity of the MCS events. WP4.5 Investigate global impact on burden of ozone of biogenic emissions from the WAM region.

  3. p-TOMCAT Chemical Transport Model • p-TOMCAT is a global offline chemical transport model • Includes a fairly detailed gas-phase / photolysis tropospheric chemistry scheme. • Also includes parametrizations for cloud mixing, boundary layer mixing, wet & dry deposition, emission inventories for surface and aircraft & lightning emissions. • Driven by ECMWF analyses (operational and ERA40) • Standard configurations are 6x6 degree and 3x3 degree horizontal resolutions with 31 levels • Used for many studies of tropospheric chemistry; including budget studies, field campaign support roles. • Recent technical development has seen a move to much higher resolutions.

  4. Tropical Tropopause Layer tracer studies • Work done by James Levine (Cambridge) • Motivation • Study troposphere to stratosphere transport to determine (any) preferred regions of entry. • Planning of SCOUT-O3 tropical campaigns • Studies used tracers in p-TOMCAT designed to allow the exchange of TTL air to lower strat. to be quantified.

  5. TTL regions 1 = Africa 5 = C. Pacific 2 = Indian O. 6 = E. Pacific 3 = Indonesia 7 = S. America 4 = W. Pacific 8 = Atlantic

  6. Release of trop. tracers T-tracers released one box below the tropopause (weighted-average of min-T and 2 PVU surfaces)

  7. Conversion to strat tracers T-tracers converted to S-tracers as a function of TTL origin and entry into the stratosphere

  8. Entry into the stratosphere 2000-01 Tropopause: min-T and 2 PVU

  9. Entry into the stratosphere 1997-8 Tropopause: min-T and 2 PVU

  10. High Resolution Chemical Modelling • Motivation • Emission datasets have global resolution of 1 degree or better : how does this impact on CTM simulations? • Improved representation of long-range transport and comparison with observations • Improved comparisons with aircraft data • Major technical changes to p-TOMCAT to achieve 1x1 and 0.5x0.5 degree global horizontal resolutions with full chemistry

  11. High resolution chemical modelling NO2 around model’s tropospause. Taken from short test run of the 0.5x0.5 version of p-TOMCAT. Transport and chemistry only.

  12. High resolution chemical modelling NO2 has strong diurnal variation. Destroyed by sunlight Resolution 640 x 320 0.56 degree Approx. 60km at equator

  13. Aircraft .v. model comparisons • Achieving a quantitative comparison of model .v. aircraft data is difficult because of the difference in scales • Fiona O’Connor used high resolution advection to demonstrate this improved comparisons with aircraft data • Ozone and CO were advected (no chemistry) for short periods using horizontal resolutions of 1x1 and 3x3 degrees for comparison with ACTO flights. • In most cases there was significant improvement in the comparison, due to the improved representation of the synoptic situation in the model

  14. Aircraft .v. model comparison 3x3 degrees

  15. Aircraft .v. model comparison 1x1 degrees

  16. Aircraft .v. model comparison 3x3 1x1

  17. Improvements to p-TOMCAT (1) Current chemistry scheme: NOx-CO-CH4-NMHCs (52 species) Addition of Isoprene (Paul Young / Guang Zeng) • Mainz Isoprene Scheme (MIM) (Pöschl et al., 2000) • ~40 isoprene-related reactions and 16 isoprene-related species: • Emission inventory from GEIA • Sensitivity studies using the Met. Office Unified Model

  18. The MIM NO3 OH C5H8 HO2 NO NALD MACRO2 HACET MGLY CH3CO3 ISO2H ISO2 MACR MACRO2H MPAN ISON CH3C(O)OOH / CH3C(O)OH PAN OH HO2 OH OH ± NO2 OH OH NO OH / NO3 OH ± NO2 HO2 OH HCHO + CO + NO2 OH

  19. Isoprene-Related Species 1. C5H8 - isoprene 2. ISO2 - hydroxy-peroxy radicals from C5H8+OH 3. ISOOH - beta-hydroxy hydroperoxides from ISO2+HO2 4. ISON - hydroxy-alkylnitrates from ISO2+NO and alkyl nitrates from C5H8+NO3 5. MACR - methacrolein and MVK and other C4-carbonyls 6. MACRO2 - hydroxy-peroxy radicals from MACR+OH 7. MACROOH - hydroxy-hydroperoxides from MACRO2+HO2 8. MPAN - peroxymethacrylic nitric anhydride and other higher peroxyacyl nitrates 9. HACET - hydroxyacetone and other C3-ketones 10. MGLY - methylglyoxal and other C3-aldehydes 11. NALD - nitrooxy-acetaldehyde (from decomposition of ISON) 12. MeCOOOH - peroxyacetic acid 13. MeCOOH - acetic acid 14. HCOOH - formic acid 15. PAN 16. acetyl radical (MeCO3)

  20. Improvements to p-TOMCAT (2) Addition of Bromine (Xin Yang / Nicola Warwick) • Bromine chemistry scheme: gas-phase and heterogeneous reactions on cloud particles and background aerosols • Br emissions from biogenic bromocarbons and sea-salt aerosol • Aim: to determine the influence of bromine chemistry on tropospheric ozone

  21. BrONO2 BrO HOBr Br2 HBr Br HBr, HOBr, Br2 BrNO2 Ocean/land Cloud particles / aerosols NO2 hv hv Br HO2,RO2 BrO O3 hv Particles hv NO, OH, RO2, BrO hv Heterogeneous or aqueous reactions ?? ~0.62 TgBr/yr CH3Br, CHBr3, CH2Br2, CH2BrCl, CHBr2Cl, CHBrCl2 hv, OH OH hv HO2, RO2, HCHO, RCHO OH wet or dry deposition NO2 hv Sea-salt ~3.1 TgBr/yr Bromine cycling scheme used in the p-TOMCAT model

  22. Emissions of Bromoform

  23. Bromine Source Studies Top-down estimates of bromoform emissions depend on location of emission: latitude (lifetime) local/non-local source

  24. Vertical Profiles of Bromoform Red – Scenario 3 (400 Gg/yr) Red – Scenario 4 (595 Gg/yr)

  25. Modelled Zonal Mean Total Bromine Zonal mean total organic and inorganic bromine in emission Scenario 6 (595 Gg CHBr3 / yr)

  26. Impact of bromine chemistry on tropospheric ozone Figure by Xin Yang

  27. Objectives • Define the scope of the chemistry (in collaboration with Leeds/UEA) • Include additional organics (e.g. isoprene, halocarbons) • Others? (e.g. oxygenates) • WAM emissions? • Define range of model experiments • Verification of new chemistry • Comparisons with measurements (high res. simulations) • Budget studies (global transport studies of emissions – impact on O3 in troposphere and lower stratosphere)

  28. Acknowledgements • p-TOMCAT: Glenn Carver, Fiona O’Connor, Nick Savage • TTL tracer studies : James Levine, Nick Savage • High resolution modelling : Glenn Carver • Aircraft / model comparisons : Fiona O’Connor • Aircraft campaign support : James Levine, Peter Cook, Nick Savage, Fiona O’Connor

  29. Current p-TOMCAT Species 1 'O(3P)' 1 'FM' 'Ox' F F F 'Atomic oxygen (ground state)' 'pptv' 2 'O(1D)' 1 'FM' 'Ox' F F F 'Atomic Oxygen (excited state)' 'pptv' 3 'O3' 1 'FM' 'Ox' T F F 'Ozone' 'ppbv' 4 'NO' 1 'FM' 'NOx' T F F 'Nitric Oxide' 'pptv' 5 'NO3' 1 'FM' 'NOx' T T F 'Nitrate Radical' 'pptv' 6 'NO2' 1 'FM' 'NOx' T F T 'Nitrogen Dioxide' 'ppbv' 7 'N2O5' 2 'TR' ' ' T T F 'Dinitrogene Pentoxide' 'ppbv' 8 'HO2NO2' 1 'TR' ' ' T T F 'Peroxynitric Acid' 'ppbv' 9 'HONO2' 1 'TR' ' ' T T F 'Nitric Acid', 'ppbv' 10 'OH' 1 'SS' ' ' F F F 'Hydroxyl Radical' 'pptv' 11 'HO2' 1 'SS' ' ' F T F 'Hydroperoxyl Radical' 'pptv' 12 'H2O2' 1 'TR' ' ' T T F 'Hydrogen Peroxide' 'ppbv' 13 'CH4' 1 'TR' ' ' F F T 'Methane' 'ppbv' 14 'CO' 1 'TR' ' ' T F T 'Carbon Monoxide' 'ppbv' 15 'HCHO' 1 'TR' ' ' T T T 'Formaldehyde' 'ppbv' 16 'MeOO' 1 'SS' ' ' F T F 'CH3OO' 'ppbv' 17 'H2O' 1 'CF' ' ' F F F 'Water Vapour' 'ppbv' 18 'MeOOH' 1 'TR' ' ' T T F 'CH3OOH' 'ppbv' 19 'HONO' 1 'TR' ' ' T T F 'HONO' 'ppbv' 20 'C2H6' 1 'TR' ' ' F F T 'Ethane' 'ppbv' 21 'EtOO' 1 'SS' ' ' F F F 'EtOO' 'ppbv' 22 'EtOOH' 1 'TR' ' ' T T F 'EtOOH' 'ppbv' 23 'MeCHO' 1 'TR' ' ' T F T 'CH3CHO' 'ppbv' 24 'MeCO3' 1 'SS' ' ' F F F 'Acetaldehyde' 'ppbv' 25 'PAN' 1 'TR' ' ' T F F 'Peroxyacetyl Nitrate' 'ppbv' 26 'C3H8' 1 'TR' ' ' F F T 'Propane' 'ppbv' 27 'n-PrOO' 1 'SS' ' ' F F F 'n-PrOO' 'ppbv' 28 'i-PrOO' 1 'SS' ' ' F F F 'i-PrOO' 'ppbv' 29 'n-PrOOH' 1 'TR' ' ' T T F 'n-PrOOH' 'ppbv' 30 'i-PrOOH' 1 'TR' ' ' T T F 'i-PrOOH' 'ppbv' 31 'EtCHO' 1 'TR' ' ' T F F 'EtCHO' 'ppbv' 32 'EtCO3' 1 'SS' ' ' F F F 'EtCO3' 'ppbv' 33 'Me2CO' 1 'TR' ' ' F F T 'Acetone' 'ppbv' 34 'MeCOCH2OO' 1 'SS' ' ' F F F 'CH3COCH2OO' 'ppbv' 35 'MeCOCH2OOH' 1 'TR' ' ' T T F 'CH3COCH2OOH' 'ppbv' 36 'PPAN' 1 'TR' ' ' T F F 'PPAN' 'ppbv' 37 'MeONO2' 1 'TR' ' ' F F F 'CH3ONO2' 'ppbv' 38 'O(3P)S' 1 'FM' 'Sx' F F F 'Stratospheric Ground State Atomic Oxygen' 'ppbv' 39 'O(1D)S' 1 'FM' 'Sx' F F F 'Stratospheric Excited State Atomic Oxygen' 'ppbv' 40 'O3S' 1 'FM' 'Sx' T F F 'Stratospheric Ozone' 'ppbv' 41 'NOXS' 1 'TR' ' ' T F F 'Stratospheric NOx' 'pptv' 42 'HNO3S' 1 'TR' ' ' T T F 'Stratospheric Nitric Acid' 'ppbv' 43 'NOYS' 1 'TR' ' ' T T F 'Stratospheric Reactive Nitrogen Species' 'ppbv' 44 'SPECH' 1 'TR' ' ' F F F 'Advected Specific Humidity' 'g/g' 45 'PT' 1 'TR' ' ' F F F 'Advected Potential Temperature' 'K' 46 'ISOPRENE' 1 'TR' ' ' F F T 'Isoprene' 'ppbv' 47 'C2H4' 1 'TR' ' ' F F T 'Ethene' 'ppbv' 48 'C2H2' 1 'TR' ' ' F F T 'Ethyne' 'ppbv' 49 'H2' 1 'CT' ' ' F F F 'Hydrogen' 'ppmv' 50 'CO2' 1 'CT' ' ' F F F 'Carbon dioxide' 'ppmv' 51 'O2' 1 'CT' ' ' F F F 'Oxygen' 'ppmv' 52 'N2' 1 'CT' ' ' F F F 'Nitrogen' 'ppmv'

  30. Global Bromoform Distribution - Surface bromoform/pptv bromoform/pptv Scenario 3 (400 Gg/yr) Scenario 4 (595 Gg/yr)

  31. Creating an Emission Dataset for Methyl Bromide • Six model emission scenarios:

  32. Methyl Bromide Seasonal Cycles Measurements from NOAA/CMDL (Montzka et al., 2003)

  33. CHBr3 Emissions (GgCHBr3/yr/km2) Total Global Emissions: 71% in coastal regions 29% in open ocean Dataset 1: 826 Gg/yr distributed according to Q&W (2003) Dataset 2: 210 Gg/yr distributed according to Q&W (2003)

  34. Tracer expt: sensitivities • Sensitivity to level of T-tracer release: insensitive • Sensitivity to dates of T-tracer release? • Continued emission vs. release at start of run?Differentiation between types of TST • Sensitivity to definition of the tropopause? • Sensitivities to model resolution and convection?

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