THE MODELS-3 COMMUNITY MULTI-SCALE AIR QUALITY (CMAQ) MODEL:

2002 RELEASE – NEW FEATURES

Jonathan Pleim, Francis Binkowski, Robin Dennis, Brian Eder, Shaocai Yu, Gerald Gipson, James Godowitch,

Tanya Otte, Thomas Pierce, Shawn Roselle, Kenneth Schere, and Jeffrey Young

Atmospheric Modeling Division, NERL/USEPA

Models-3/CMAS WorkshopRTP, NC

October 21, 2002

CMAQ Chemical Transport ModelJune 2002 Release

• Advection– Piecewise parabolic method (PPM)– Bott scheme

• Vertical Diffusion– Eddy-diffusivity (Kz)– Asymmetric Convective Model (ACM)

• Horizontal Diffusion– Eddy-diffusivity with Kh grid size dependent

• Cloud Processes

– Aqueous chemistry and sub-grid clouds adapted from RADM

– Simple grid-resolved cloud scheme at all grid resolutions

• Plume in Grid– Embedded Lagrangian plume with gas-phase

photochemistry (aerosols will be added after June 2002)

• Dry deposition– RADM dry deposition model– M3dry: Adjunct to the PX Land Surface Model

• Gas-phase Chemical Mechanisms

– RADM2– CB4– SAPRC99 – All mechanisms linked to aerosol module and

aqueous chemistry

• Gas-phase Chemistry Solvers– Quasi-steady state approximation (QSSA)– SMVGEAR– Modified Euler Backward Iterative method for

all mechanisms

Updated Aerosol Model (Aero3)• Lognormal size distribution (g and Dg)

– Aitken mode (0-0.1 µm) – Accumulation mode (0.1-2.5 µm)– Coarse (PM10 - PM2.5)

• Aerosol processes:– Nucleation (revised)– Coagulation– ISORROPIA semivolatile equilibrium model– Clouds - CCN, aqueous chemistry, wet deposition

PM2.5}

• Aerosol chemistry– Inorganic: Sulfate,Nitrate, Ammonium

– Secondary anthropogenic and biogenic organic (updated yields and added semivolatile partitioning)

– Speciated primary emissions

• Elemental carbon, organic carbon, sulfate, nitrate

• Future: soil dust, sea salt

– Heterogeneous reaction of N2O5 -> HNO3

• Regional haze– Visibility estimates in deciviews

deciView = 10 ln (ext / 0.01)

• Explicit hour-averaging of CMAQ output species• Dynamic memory allocation / windowing

• New Meteorology Chemistry Interface Processor (MCIP2)– MM5v3 compatible– Surface and PBL parameters passed through – Compatible w/ PX LSM and M3dry

• Emissions– Sparse Matrix Operator Kernel Emissions

(SMOKE) System– Biogenic Emissions Inventory System (BEIS3)

• Plume rise modifications (SMOKE)– Corrected stable plume rise: Greatly reduces low

level emissions– Updated Neutral and Unstable algorithms– Added option for updated initial vertical plume

spread algorithm: generally much narrower initial spread

– Effects of these changes are still being evaluated

Model Domains

32 km

8 km2 km

Evaluation

• Nashville 1999

• Atlanta 1999

• Houston 2000

• Annual speciated PM 2001

• Tampa Bay 2002

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