CMAQ (Community Multiscale Air Quality) pollutant Concentration change horizontal advection vertical advection horizontal dispersion vertical diffusion chemical reaction deposition (wet & dry) emission A 3-D chemical transport model that sovles the mass conservation equation: Gas-phase species:Ozone, volatile organic compounds (VOCs), ammonia, reactive nitrogen, etc Aerosol-phase species:Sulfate, nitrate, ammonium, organics, etc Gas-phase chemistry mechanism:SAPRC99 or CB-05 Aerosol dynamics:3 log-normal size distributions

CMAQ Spatial & Temporal Resolutions Temporal Resolution: – Takes input at hourly time time steps – Runs at sub-hourly time steps (adaptive) – Provides output of hourly concentrations & deposition rates Vertical Resolution: – Typically layers from the surface to ~15km with more layers concentrated near the surface Spatial Resolution follows WRF, but domain is smaller than WRF – Examples: 36-km for continental US: 94 x 140 = 13,169 grid cells per layer 12-km for California: 285 x 315 = 89,775 grid cells per layer 12-km for PNW: 95x 95 = 9,025 grid cells per layer 1-km for an urban area – Can be nested (following WRF)

CMAQ Spatial Resolution Example 12-km grids over the PNW

CMAQ Inputs and Outputs Emission Models: MEGAN, BlueSky, SMOKE, etc Emission Models: MEGAN, BlueSky, SMOKE, etc WRF CMAQ Gridded hourly P, T, U, V, W, Q, R, precip & LULC information LULC Data, Anthropogenic Emission Inventory, Fire Data Gridded & Speciated Hourly Emission Rates Chemical Boundary Conditions Gridded, hourly ambient concentrations and deposition rates

AIRPACT-3 Forecast Link N Deposition Rates CMAQ Output Examples December 2010 Nitrogen Deposition

Coupled WRF-CMAQ WRF CMAQ AQPREP Prepares virtual CMAQ-compatible input meteorological files AQPREP Prepares virtual CMAQ-compatible input meteorological files Aerosol Optical Properties, Cloud Condensation Nuclei Ozone Aerosol Optical Properties, Cloud Condensation Nuclei Ozone Feedbacks between Air Quality and Meteorology: Aerosol scattering & absorption effects on shortwave radiation (using CAM option) and photolysis Aerosol impact on cloud microphysics Ozone impact on longwave radiation (using RRTMG option) Coupler

CMAQ Architecture, etc Runs in linux/unix environment: – ….. Language – 99% Fortran (Intel or PGI compiler) – < 1% C File format – netCDF, though different convention than WRF cvs for version control

CMAQ Applications Daily air-quality forecast Visibility reduction Impact of climate change on air quality Impact of air quality on meteorology (coupled WRF-CMAQ)

The MEGAN model MEGAN estimates emissions of non-methane biogenic volatile organic compounds (BVOC) using geo-gridded, species and vegetation density-dependent emission factors (EF) for various BVOC. These EFs represent average emission rates for a given geographic area under standard temperature and light conditions. Emission rates are computed using actual light and temperature data for a model domain and time period to simulate the effect of deviations of these factors from standard conditions on emissions. The EF (Ɛ) is also multiplied by dimensionless coefficients which simulate the effects of leaf age (Ɣ age ), within- canopy conditions (Ɣ CE ), and soil moisture (Ɣ SM ) on emissions.

MEGAN Spatial and Temporal Resolutions

MEGAN Inputs and Outputs Input – Vegetation species distribution and density information – LAI – Temperature – Radiation – Soil Moisture Output – Biogenic VOC emissions – Working on N 2 O and CH 4 emission rates

MEGAN Architectures, etc Various versions – Visual Basic/Python/ArcGIS – Fortran version compatible with CMAQ – Online version built in WRF-Chem

MEGAN Applications Provides input for global and regional air- quality/chemical transport models – Impact of biogenic VOC on ozone formation – Impact of BVOC on secondary organic aerosol formation – Biosphere-Atmosphere Exchange