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Performance of the EMEP aerosol model: current results and further needs Presented by Svetlana Tsyro (EMEP/MSC-W). EMEP workshop on Particulate Matter Measurements & Modelling, New Orleans, April 20-23, 2004. Title. Outline. Short description of the aerosol model

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  1. Performance of the EMEP aerosol model: current results and further needs Presented by Svetlana Tsyro (EMEP/MSC-W) EMEP workshop on Particulate Matter Measurements & Modelling, New Orleans, April 20-23, 2004 Title

  2. Outline • Short description of the aerosol model • Model performance evaluation • Comparison with observations of calculated : • PM10 and PM2.5 masses • PM chemical composition, particle-bound water • particle numbers • Identified needs for the model further improvement • and validation • Summary / conclusions Meteorologisk Instituttmet.no

  3. EMEP Aerosol model (UNI-AERO): Aerosol components:SO42-, NO3-, NH4+, OC, EC, dust , sea salt + aerosol water (not yet included: SOA, primary biogenic OC, wind blown dust) Aerosol size distribution - 4 monodisperse size modes: nucleation, Aitken, accumulation, coarse Assumption:particles in the same mode have the same size and the same chemical composition (internally mixed) Accounts for aerosol dynamics (MM32):nucleation, condensation, coagulation, ‘mode merging’ Output: size resolved aerosol mass and number concentrations Resolution: 50 x 50 km2 , 20 layers up to 100 hPa Meteorologisk Instituttmet.no

  4. Gas emissions SOx Irreversible chemistry (gaseous and aqueous) H2SO4 PM emissions NOx NH3 PM2.5 OC EC Dust Aitken, accum. EQSAM Gas/aerosol & aerosol water Dust coarse Coarse PM SO4, HNO3 / NO3 NH4 / NH3, Na, Cl sea salt Aerosol dynamics (MM32) Nucleation H2SO4-H2O  SO4 Condensation H2SO4  SO4 Coagulation N, M, D Mode merging gases aerosol Dry deposition Wet scavenging PM-bound water Output: number and mass size distribution, chemical composition, PM2.5, PM10 (PM1) Schematic computational structure of UNI-AERO Meteorologisk Instituttmet.no

  5. Annual mean concentrations of PM in 2001 PM10 PM2.5 Aerosol model Measure-ments spatial coverage EMEP obs Systematic underestimation Meteorologisk Instituttmet.no

  6. Annual mean PM10 and PM2.5 (2001, EMEP) N=25 Bias=-51% Corr=0.15 N=17 Bias=-46% Corr=0.61 elevated C. Europe: bias = - 41% corr = 0.59 Spain: bias = - 67%, corr = 0.44 wind eroded & Saharan dust The model underestimates measured PM10 and PM2.5 PM10 – complex pollutant. To explain the discrepancies between calculated and measured PM10 verification of the individual components is needed. Meteorologisk Instituttmet.no

  7. Annual mean SIA (2001, EMEP) Sites with PM10 measurements Bias=-19% Corr=0.81 Sites without PM10 measurements Does not help to explain the discrepancy between modelled and measured PM Bias= 15% Corr=0.89 For that, co-located and concurrent measurements of ‘all’ aerosol components is needed Meteorologisk Instituttmet.no

  8. SIA (2001): model vs. EMEP measurements Bias = 9% Corr = 0.71 Bias = 7% Corr = 0.84 Bias = 19% Corr = 0.91 Meteorologisk Instituttmet.no

  9. What is needed: “component-wise” verification of modelled PM EXAMPLE for Birkenes, Norway (2001) Meteorologisk Instituttmet.no

  10. PM10 components Meteorologisk Instituttmet.no

  11. PM10 components PM emissions validation Meteorologisk Instituttmet.no

  12. One more example: Vienna Daily PM2.5 (June 1999 - June 2000): Meteorologisk Instituttmet.no

  13. Daily series of SO4, NO3 and NH4 in PM2.5 SO4 NO3 Na NH4 EC OC PM emissions validation EC Meteorologisk Instituttmet.no

  14. Chemical composition of PM2.5 and PM10 (1): Full chemical mass closure is rarely achieved . Unaccounted PM mass - up to 35-40% • Non-C atoms in organic aerosol  Particle-bound water •  Measurement artefacts Gravimetric method (Reference, EU and EMEP) for determining PM mass requires 48-h conditioning of dust-loaded filters at T=20C and Rh=50% -does not remove all water! At Rh=50% particles can contain 10-30% water Gravimetrically measured PM mass does not represent dry PM mass!!! Meteorologisk Instituttmet.no

  15. Chemical composition of PM2.5 and PM10 (2):To what extend can particle-bound water explain the model underestimation of measured PM? PM10 PM25 Unaccounted PM mass in obs Aerosol water in model results PM2.5 Austria,1-6/2000 (AUPHEP) Vienna Streithofen Meteorologisk Instituttmet.no

  16. Modelleddry PM2.5 vs. Identified PM2.5 mass Modelledwater in PM2.5 vs. Unaccounted PM2.5 mass Meteorologisk Instituttmet.no

  17. Model calculated dry PM2.5 (blue) and PM2.5 including aerosol water (black) vs. measured PM2.5 (red) Accounting for water in modelled PM2.5 gives better agreement with measurements BUT:verification of model calculated aerosol water with measurements is needed Meteorologisk Instituttmet.no

  18. Accounting for particle-bound water in PM2.5 Model calculations vs. gravimetric PM2.5 (EMEP, 2001) Dry PM2.5 + water Dry PM2.5 N=13 Bias=- 47% Corr=0.69 N=13 Bias=-28% Corr=0.68 Smaller negative bias Meteorologisk Instituttmet.no

  19. Accounting for particle-bound water in PM10 Model calculations vs. gravimetric PM10 (EMEP, 2001) Dry PM10 Dry PM10 + water N=13 Bias=- 64% Corr=0.26 N=13 Bias=-38% Corr=0.29 Smaller negative bias Slightly improved correlation Meteorologisk Instituttmet.no

  20. Verification of daily PM2.5 with EMEP measurements Meteorologisk Instituttmet.no

  21. Daily PM2.5 vs. EMEP measurements Hourly PM2.5 Aspvreten, SE 2000 Meteorologisk Instituttmet.no

  22. Aitken number (102/cm3) at Hyytiälä, Finland, 2000 Hourly Hourly, october Hourly, december Daily Meteorologisk Instituttmet.no

  23. Hourly Aitken number: nucleation effect No nucleation (July 12-17, 2000) Nucleation events (June 10-22, 2000) Hyytiälä, Finland BIOFOR  Prediction of nucleation events  Number of nucleated particles  Growth of newly formed particles Meteorologisk Instituttmet.no

  24. Accumulation (0.1 – 0.5 μm)particle number, 2000(10-2/cm3) Aspvreten, hourly Aspvreten, daily Värriö, hourly Värriö, daily Meteorologisk Instituttmet.no

  25. Daily total particle number, Austria (AUPHEP) Vienna urban Streithofen rural Emissions + meteorology Meteorologisk Instituttmet.no

  26. Summary on the model performance • The EMEP aerosol model underestimates PM2.5 and PM10 (SOA and natural dust not yet included) • Accounting for particle-bound water improves the agreement between model calculated and gravimetrically determined PM mass • Verification of model calculated aerosol water • Largest discrepancy: OC, EC, mineral dust • Implementation of SOA, wind blown dust. • Emissions chemical speciation! • Particle number – more difficult (esp. Aitken): • Emissions size disaggregation! Aerosol dynamics Meteorologisk Instituttmet.no

  27. Measurement needs • Information on PM chemical composition is essential for further improvement of PM mass calculations • Co-located concurrent measurements are needed: • (process understanding, source allocation) • Particle-bound water • Particle number concentration: size distribution • Particle fluxes (dry deposition) over different land-use types, size resolved • Wet scavenging • Vertical profiles Meteorologisk Instituttmet.no

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