Development and Initial Applications The 7th CMAS Workshop CMAQ Dust Module: Development and Initial Applications Daniel Tong$, Rohit Mathur+, David Mobley+, David-C Wong+, Shaocai Yu$, Hsinmu Lin$, Tianfeng Chai+ $ ARL/NOAA, on assignment from Science & Technology Corp. + Atmospheric Modeling and Analysis Division, US EPA, RTP, NC Acknowledgement: We thank Jon Pleim for comments, Marc Houyoux and Alice Gilliland for CMAQ input, Steve Howard for help with data processing. Disclaimer: This work constitutes a contribution to the NOAA Air Quality Program. Although it has been reviewed by EPA and approved for presentation, it does not necessarily reflect their policies or views.

Environmental Impacts of Dust Particles Climate: Direct: absorbing & scattering; Indirect: CCN; Bio-available iron  phytoplankton  CO2 sink; Atmospheric Chemistry: Reduce photolysis rates by over 50%; Reacting platform for O3, HO2 and N2O5; Buffering acid rain; Air Quality: Reduce visibility; PM air quality standards; Human Health: Sources for toxic metals; Ubiquitous constituents of inhalable PM; (Source: IPCC, 2007)

(Source: US EPA, NEI Air Pollutant Emissions Trends, 2006) PM2.5 Emissions in the U.S. ? Anthropogenic (Source: US EPA, NEI Air Pollutant Emissions Trends, 2006)

Calculating Natural Dust Emissions in U.S. Key factors: Dessert and agricultural land; Soil moisture (rain & snow cover); Soil components (sand, silt and clay); Vegetation coverage and roughness Surface wind speed); Threshold wind speeds (Source: blog.maricopanewhomes.net)

Dust Emission Algorithm Dust production using Owen’s Equation (Marticorena et al, 1997): Threshold Friction Velocity (source: Gillette 1980, 1988): Soil type Sand Loamy Sand Sandy Loam Silt Loam Loam Sandy Clay Loam Silty Clay Loam Clay Loam Sandy Clay Silty Clay Clay Desert Land 0.42 0.51 0.66 0.34 0.49 0.78 0.33 0.71 0.56 Agricultural 0.28 0.29 1.08 0.64 0.54

Size Distribution & Chemical Speciation Size Distribution -- Bins (source: Marticorena et al, 1995; Ginoux et al., 2001; Draxler et al., 2001): Threshold wind speeds from wind tunnel experiments Threshold values dependent on average particle sizes for each bin Chemical Speciation (Pelt & Zobek, 2007; Ansley et al., 2006): 99% of PM2.5 emissions into PMFINE (eventually A25J); 1% of PM2.5 emissions into PSO4, PNO3, PEC & POA; 100% of PM2.5-10 emissions into PMC (eventually ASOIL);

CMAQ Configuration Emissions Meteorology CMAQ (version 4.6) 2002 NEI for anthropogenic emissions; BEIS 3 for biogenic emissions; Year-specific wildfires and prescribed burning; Natural dust emissions turning on and off. Meteorology MM5 with Pleim-Xiu Land Surface module on; CMAQ (version 4.6) Jan. 1 – Dec. 31, 2002; Domain: Continental US, N Mexico and S. Canada; MOZART-2 for lateral boundary conditions; CB05 gas chemistry and AE4 aerosol modules; Online calculation of photolysis rates;

Natural Dust (PM2.5) Emissions in 2002

Dust Emissions over Western Canadian

Topography Filter Impact of topography on dust availability (Prospero et al., 2001)

Monthly Profile of U.S. Dust Emissions Dust emissions most active in Spring

PM2.5 Emissions by Sector (2002) Top PM2.5 emission sectors (and uncertainties!): Miscellaneous (anthropogenic) and Natural Emissions

Dust Impact on PM2.5 and O3 PM2.5 Change O3 Change (a Major Dust Episode in late May 2002) PM2.5 Change O3 Change Dust impact on O3 through reduced photolysis rates only; Direct interactions of O3 with dust not implemented.

Dust Impact on PM2.5 Performance (dust contribution < 1 mg/m3) Without Dust NMB = -26.2% With Dust NMB = -25.2% Outside dust plumes, the addition of natural PM emissions improves CMAQ performance to predict PM2.5

Dust Impact on PM2.5 Performance (dust contribution 1 ~ 2 mg/m3) w/o dust NMB = -11% w/ dust NMB = 9% Improved performance in areas of moderate impact

Dust Impact on PM2.5 Performance (dust contribution: > 3 mg/m3) Inside plume, resolved under-prediction, but working too hard!

Conclusion Annual natural PM2.5 emissions in the U.S. Impact of natural emissions on air quality simulation Contribute to 30% of primary PM2.5 emissions (preliminary) Most active in Spring Mostly from Southwest and Rocky Mountain regions Dust emissions affect both PM2.5 and O3 concurrently The additional emissions improve CMAQ performance for PM2.5, but cause over-prediction inside the plume;

Future Work Data verification Implementation for air quality forecast Comparison with more ground observations; AOD calculation and comparison with satellite data; Change PREMAQ to extract soil type and moisture from MET model; Update CMAQ codes to include dust module;