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Christoph Knote, Dominik Brunner Empa, Materials Science and Technology, Dübendorf, Switzerland

Interactions of aerosols and gases with clouds and precipitation in the online-coupled regional chemistry transport model COSMO-ART. Christoph Knote, Dominik Brunner Empa, Materials Science and Technology, Dübendorf, Switzerland CMAS annual conference, Chapel Hill (NC), 2011. meteorology.

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Christoph Knote, Dominik Brunner Empa, Materials Science and Technology, Dübendorf, Switzerland

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  1. Interactions of aerosols and gases with clouds and precipitation in the online-coupled regional chemistry transport model COSMO-ART • Christoph Knote, Dominik Brunner • Empa, Materials Science and Technology, Dübendorf, Switzerland • CMAS annual conference, Chapel Hill (NC), 2011

  2. meteorology preprocessor inorganics SOA gas-phase natural emissions photolysis MADEsoot extended 12 modes explicit soot aging PAPA online calculation of photolysis rates INT2COSMO-ART IC/BC, emissions ISORROPIA II SORGAM / VBS COSMO non-hydrostatic NWP BVOCs RADMK extended RADM2 + add. isoprene reactions + updated rate constants + hetero. N2O5 hydrolysis Seasalt aerosols Dust Pollen COSMO-ART (Vogel et al., ACP, 2009) • regional chemistry transport model based on COSMO • online-coupled gas-phase chemistry and aerosol processes • studies of aerosol direct and indirect effects

  3. Henne et al., ACP, 10, 2010 Evaluation results (EMEP) summer winter spring fall O3 NO2 overestimation of SO2 concentrations SO2 Knote et al., Geosci. Model Dev. Disc., 4, 1809-1874, 2011 meas. model model meas.

  4. Evaluation results (EUCAARI AMS) too low sulfate too high nitrate Knote et al., Geosci. Model Dev. Disc., 4, 1809-1874, 2011

  5. Coupling to MESSy SCAV Tost et al., ACP, 2006 Scavenging (cloud droplets & rain drops) • gases: explicit description of transfer process kinetics (option for Henry‘s law equilibrium) • aerosols: Brownian motion + interception + impaction, parameterized nucleation Aqueous-phase chemistry • MECCA (Sander et al., 2005) + additions from CAPRAM (Ervens et al., 2003) • reduced version with sulfur-oxidation-focused mechanism • 45 transfer + chemical reactions, 35 species • ODE system solved via KPP

  6. droplet evaporates net mass transfer from smaller to larger (Acc. mode) aerosols Cloud processing of aerosols HNO3 SO2 aqueous chemistry H2O2 O3 NH3 dN/dlogDp diameter MADEsoot modes: 2 nucleation, 2 accumulation, 1 fresh soot

  7. t = t0 t = t0 + dt gas/aq. transfer washout condensation aq. chemistry evaporation Adaptations to regional scale Original SCAV formulation: • OK for GCMs with dt = O(1 h)NOT OK for COSMO-ART with dt = O(1 min) • liquid-phase species are now transported,partial evap./cond. of cloud possible(consistent with COSMO microphysics)

  8. time-step dependent! apply only to fraction of aerosols: fraction of freshly condensed cloud water (from COSMO microphysics) Adaptation: activation scheme empirical. derived from meas. of Svenningsson (1997) and Martinsson (1999) Stier et al. 2005 nucleation and growth brownian motion Tost et al., ACP 6, 565-574, 2006

  9. 2D flow-over-hill study • initial values / boundary profile:from 3D COSMO-ART simulation, 12 UTC summer in Payerne (CH) • 100 x 40 grid cells, 0.0045° (~500m) • Runge-Kutta time integration, dt = 15s • T/qv profile: Weisman Klemp, MWR, 1982u = 20 m/s Liquid precipitation content („rainfall“) Liquid water content (LWC)

  10. △SO2 (gas-phase) 2D study results △SO42- (aerosol) S wet deposition

  11. △SO2 (gas-phase) 2D study results SO2 scavenged △SO42- (aerosol) SO42- produced S wet deposition mass deposited

  12. △SO2 (gas-phase) 2D study results SO2 scavenged SO42- Aitken mode △SO42- (aerosol) SO42- produced SO42- accumulation mode S wet deposition mass deposited

  13. △SO2 (gas-phase) 2D study results SO2 scavenged SO42- Aitken mode △SO42- (aerosol) SO42- produced SO42- accumulation mode S wet deposition mass deposited cloud processing active

  14. 2D study results Chemistry boundary profile: Swiss midlands, 12 UTC, summer. measured pH: 5.9 (NABEL station Dübendorf, Swiss midlands, summer 2008 mean) simulated pH: 5.6 - 6 cloud droplet acidity Conclusions • scavenging working for gases and aerosols • oxidation of sulfur visible • cloud processing active let‘s go 3D!

  15. Sulfate aerosols (level slice at 1 km) Realistic simulation COSMO-ART-SCAV October 2008 17 km horiz. resolution 40 vertical levels full gas-phase chemistry and aerosols efficient sulfate aerosol production on cloud evaporation Cloud pH large variability in cloud pH

  16. Realistic study results ref. EMEP station data SCAV meas. SO2 ref. ref. meas. SCAV SCAV meas. EUCAARI AMS

  17. Conclusions • Successfulcouplingof COSMO-ART with SCAV • Detaileddescriptionofscavengingandaqueous-phase chemistry • Strong reductions in SO2concentrations • Improvedchemicalcompositionof PM1,nonref, but reduced total mass • Assumptionsmade in aq.-phase schemesmight not workfor online-coupledmodels

  18. prognostic prognostic prognostic prognostic Coupling overview gases kinetic transfer (ODE system) kinetic transfer evaporation evaporation rain droplets aqueous chemistry production aqueous chemistry cloud droplets wet deposition Brownian motion / nucleation Brownian motion / interception / impaction evaporation evaporation particles

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