1. Charmex workshop Trieste 1/Total http://charmex.lsce.ipsl.fr Working sesssion « chemical processes » overview Relevant questions : -VOC reactivity, oxidized VOC budget, => radical budget, Prod (O3) ? - Caracterizing air mass processing ? - Organic aerosol formation in relation to precursors - Aerosol evolution, oxidative state, other properties - How to include these processes in models Common studies, Common publications ?

2. Charmex workshop Trieste 2/Total http://charmex.lsce.ipsl.fr Working sesssion « chemical processes » overview Proposed talks : Agnes Borbon, overview over results of the CARBOSOR project Nora Zannoni, Results on OH reactivity Evelyne Freney, SOA formation and relation to precursor gases Jean Sciare, Organic aerosol oxidative state Open discussion (introduction) :

3. Charmex workshop Trieste 3/Total http://charmex.lsce.ipsl.fr Working sesssion « chemical processes » Introduction to discussion : Gases ….. Remaining issues for missing VOC reactivity? which missing compounds, how to measure, model them? HOx budget calculations: OH budget to be constrained with total VOC reactivity? Air mass classification from reactive compound ratios,

4. Charmex workshop Trieste 4/Total http://charmex.lsce.ipsl.fr

5. Charmex workshop Trieste 5/Total http://charmex.lsce.ipsl.fr

6. Charmex workshop Trieste 6/Total http://charmex.lsce.ipsl.fr

7. Charmex workshop Trieste 7/Total http://charmex.lsce.ipsl.fr Ozone during low-altitude flights (400-700 m a.s.l.): general findings  Various ozone levels recorded (30-80 ppbv), no major pollution episode  No systematic ozone diurnal evolution over sea  Daytime O 3 increase in 9 out of 15 daytime flights  Daytime growth rate by ~ 1-2 ppbv/h (less than usually observed in the continental boundary-layer)  Daytime ozone decrease in a few cases O 3 (ppbv) Hour UTC Common study with modellers Ozone levels (+ other measurements) Ozone net production / loss Chemical regime diagnostics

8. Charmex workshop Trieste 8/Total http://charmex.lsce.ipsl.fr Working sesssion « chemical processes » overview Introduction to discussion : Aerosol (1) Kinetics of SOA build-up, hope to get observational data ? OA / O3 plots, an alternative for data exploitation ? SOA / VOC precursor relationships in near source regions (as for WP1 biogenic flights ), a possibility to derive SOA yields from terrain data ?

9. Charmex workshop Trieste 9/Total http://charmex.lsce.ipsl.fr Kinetics of SOA formation BC et CO : dilution tracer -log(NOx/NOy) : proxy of photochemical aging Build-up of OA (AMS) as photochemical age increases (MONA et PTRMS) in Paris plume Freney et al., ACP, 2013 megapoli Urban Plume (Paris MEGAPOLI) ? SAFMED 2013 Sampling air masses with different degrees of processing Chemical age

10. Charmex workshop Trieste 10/Total http://charmex.lsce.ipsl.fr Rationale of OA vs. O X (O 3 + NO 2 ) plots VOC + OH -> … -> …. -> a 1 O X + a 2 SVOC under high NOx conditions, a similar VOC mix, a given partition ratio for SVOC into gaz and particle phase, => the SOA to O X ratio or slope a 1 /a 2 expresses the ability of air masses to produce SOA normalised by chemical reactivity => Use this ratio for model evaluation, normalising out errors in emissions, OH level

11. Charmex workshop Trieste 11/Total http://charmex.lsce.ipsl.fr Results from the Megapoli campaign ATR fligthts in the Paris plume Ox (O 3 +NO 2 ) in ppb Zhang et al., under preparation, 2014 Observation Black: observation AMS OA vs Ox Purple : CHIMERE simulations with VBS (Volatility basis set) scheme, high yield Green, the same, but with low yields corresponding to high NOx conditions Could these type of plots also be prepared for Charmex data ?

12. Charmex workshop Trieste 12/Total http://charmex.lsce.ipsl.fr SOA / VOC precursor relationships in near source regions: a possibility to derive SOA yields from terrain data ? isoprene + OH -> a 1 C MVK+MACR +…. + a 2 C SOA Aerosol yield a 2 can be derived from other 3 paraleters or at least test different SOA yields from isoprene oxidation in models

13. Charmex workshop Trieste 13/Total http://charmex.lsce.ipsl.fr Working sesssion « chemical processes » Points for discussion : Aerosols (2) Aerosol oxidation state: how does it evolve with distance from sources and with time ? Molecular analysis, what can we learn from it ? Mixing states : common studies between HTDMA + ATOFMS data sets Interaction between aerosol compounds, OA + sulfate ? aerosol + gaz interactions, what is the available surface of dust, BC, aerosol ?

14. Charmex workshop Trieste 14/Total http://charmex.lsce.ipsl.fr Working sesssion « chemical processes » Points for discussion : Interaction observation – modelling:  Model evaluation  Model - Improvement  Use for budget studies Models : in WP1 /WP2: Polyphemus, CHIMERE, Méso-NH, others ? Mocage, WRF-Chem, ….. Gecko - 0D ? =>=>=> « General » evaluation campaign observations + long term data sets =>=>=> Specific « evaluation » with data sets isolating processes OA / precursor gas ratios Testing of different SOA schemes : Pun et al. 2006 -> CHIMERE Volatility basis set with adaptaions Polyphemus module Meso-NH module Simplified set derived from GECKO 3D (thesis INERIS LISA) Others …