Utah Wintertime PM2.5 Modeling Lance Avey Utah Division of Air Quality

Ammonium Sulfate 9% Organic Carbon 20% Ammonium Nitrate 58% Other 5% Elemental Carbon 5% Dust 2% PM2.5 Speciation NOx + VOCs HNO 3 (nitric acid) HNO 3 + NH 3 NH 4 NO 3 (particulate)

NAAQS for PM2.5 EPA revised the NAAQS for PM2.5 in December of 2006 –24-hr standard was lowered from 65 micrograms per cubic meter (µg/m 3 ) to 35 µg/m 3 –Annual standard was retained at 15 µg/m 3 –Retained the 24-hr standard for PM10 at 150 µg/m 3

State Implementation Plan Basic Elements include: –Modeled Attainment Demonstration (with chemistry) –Emissions Inventories –Emission Limits –Attainment Dates (2 – 7 years after SIP)

Retrospective Modeling Replicate the meteorological, emissions, and chemistry of past high PM2.5 episodes In the future, the same meteorology and chemistry will cause high PM2.5 episodes Future emissions will change –Population Growth, new technologies, cleaner vehicles Allows DAQ to evaluate how future changes in emissions (and control strategies) effect PM2.5

Emissions Point, Area, Mobile

36/12/4 km Horizontal Domain 37 vertical layers –1 st layer at ~ 12 meters – 10 layers below 250 meters –Initialization uses 12km-NAM Re-analysis Pleim-Xiu LSM & Surface Layer, ACM2 PBL Simulations were ran in 5.5 day segments Observational and Analysis Nudging UDAQ Retrospective WRF

Modeling Domain 4km x 4km

WRF Output 2010 Jan 04 – Midnight Local Time

CMAQ Nitrate (ug/m3) 2010 Jan 04 – Midnight Local Time

Future Year Modeling -Same Meteorology -Same Chemistry -Changes in Emissions