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Xiaoming Hu and Yang Zhang North Carolina State University, Raleigh, NC Mark Z. Jacobson

EVALUATION AND IMPROVEMENT OF GAS/PARTICLE MASS TRANSFER TREATMENTS FOR 3-D AEROSOL SIMULATION AND FORECAST. Xiaoming Hu and Yang Zhang North Carolina State University, Raleigh, NC Mark Z. Jacobson Stanford University, Stanford, CA. Outline. BACKGROUND AND OBJECTIVES PRELIMINARY RESULTS

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Xiaoming Hu and Yang Zhang North Carolina State University, Raleigh, NC Mark Z. Jacobson

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  1. EVALUATION AND IMPROVEMENT OF GAS/PARTICLE MASS TRANSFER TREATMENTS FOR 3-D AEROSOL SIMULATION AND FORECAST Xiaoming Hu and Yang Zhang North Carolina State University, Raleigh, NC Mark Z. Jacobson Stanford University, Stanford, CA

  2. Outline • BACKGROUND AND OBJECTIVES • PRELIMINARY RESULTS • Stand alone condensation solvers • Gas/particle mass transfer approaches • 3-D test using WRF/Chem-MADRID • SUMMARY

  3. Bulk Gas Phase Condensable Species Volatile Species Nucleation Mass Transfer to/from the Surface of Particles Thermodynamic Equilibrium at the Particle Surface Condensational Growth Shrinkage by Volatilization Size-resolved PM Chemical Composition Coagulation Major Aerosol Dynamics Processes

  4. Gas/Particle Mass Transfer Approaches in AQMs

  5. Solvers for Condensation Equation • Eulerian approaches (e.g., Bott; Walcek) • Lagrangian approaches (e.g., Trajectory-Grid) • Hybrid (e.g., Analytical Predictor of Condensation (APC) scheme)

  6. Objectives • Identify a reliable yet efficient condensation scheme • Improve gas/particle mass transfer treatment • Apply improved modules for 3-D AQ simulation and forecast

  7. Test of Condensation Schemes Case from Seigneur et al. (1986) and Zhang et al., (1999)

  8. Sensitivity of APC scheme to Size Resolution Case from Seigneur et al. (1986)andZhang et al., 1999

  9. ICs for Test of Gas/Particle Mass Transfer Approaches

  10. Test of Gas/Particle Mass Transfer ApproachesHong Kong on May 7, 1998 • H+(aq) + Cl-(aq)  HCl(g) • H+(aq) + NO3-(aq)  HNO3(g) • NH4+(aq) + OH-(aq)  NH3(aq)+H2O(aq) • NH3(aq)  NH3(g) • 2Na+(aq)+SO42-(aq)  Na2SO4(s)

  11. Comparison with Observed PM Size DistributionHong Kong on May 7-8, 1998 • Similar obs. PM size • distribution on May 7-8 • Similar meteorology but • higher emissions on May 8 • Kinetic approach with • emissions gives the best fit Box model simulations

  12. CPU time of MADRID

  13. Application of WRF/Chem-MADRID with TexAQS2000 Episode & Resolution • Period: Aug. 28 – Sept. 2, 2000 • Domain: 88 x 88 grid cells • Horizontal resolution: 12 km • Vertical resolution: 57 layers Meteorology • Yonsei Univ. PBL scheme • NOAH land-surface scheme • Goddard short wave radiation • Rapid and accurate rad. tran. model (RRTM) long wave rad. Initial & Boundary Conditions • North Amer. Reg. Reanalysis Emissions • Gas: TCEQ inventory • PM: NEI v3 Gulf of Mexico • Chemistry • Gas: CBM-Z • Aerosol: • MADRID (Equilibrium vs. Kinetic)

  14. Comparison with Observations Equilibrium Kinetic APC

  15. Nitrate Predictions: Equilibrium vs. Kinetic Approaches Equilibrium • HNO3(g) + NaCl(s) NaNO3(s) + HCl(g) • HNO3(g) + Cl-(aq) NO3-(aq) + HCl(g) Kinetic APC Fine mode Coarse mode

  16. Predicted Size-Resolved Composition at Galveston Equilibrium Kinetic APC

  17. Summary • Bulk equilibrium approach failed to reproduce the observed size-resolved composition under conditions with high concentration of reactive species in the coarse particles. • Kinetic/hybrid approaches with APC are competitive for 3-D application in terms of both accuracy and computational efficiency. • WRF/Chem-MADRID with kinetic mass transfer approach predicts more coarse mode nitrate than the equilibrium approach for the TexAQS2000 episode.

  18. Acknowledgements • NOAA # DW13921548 and NSF Career Award # Atm-0348819 • Jerome Fast, William Gustafson Jr., PNNL, Richland, WA • Georg Grell and Steven Peckham, NOAA, ESRL, Boulder, CO • All members from Air Quality Forecasting Lab, NCSU, Raleigh, NC

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