Krish Vijayaraghavan, Prakash Karamchandani Christian Seigneur AER San Ramon, CA 3rd Annual CMAS Models-3 Conference October 18-20, 2004 Chapel Hill, NC Application of CMAQ-APT to the Central California Ozone Study

Overview Limitations of 3-D grid modeling CMAQ-APT: Plume-in-grid (PiG) air quality model State-of-the science treatment of stack plumes at the sub-grid scale 3-D grid host model - CMAQ Reactive plume model – SCICHEM Impact of PiG treatment on ozone and HNO 3 concentrations

Interface between CMAQ and SCICHEM Domain, grid information geophysical data meteorological data deposition velocities CMAQSCICHEM Emissions, IC/BC Output puff information Point source emissions Dump puffs chemical concentrations chemical concentrations I/O API I/O API I/O API I/O API Standard SCICHEM output Puff diagnostics (process analysis) Control File

Improvements to CMAQ-APT Optional treatment for the effects of building downwash on plume rise and dispersion (PRIME) Incorporation of CMAQ code updates released in September 2003 (version 4.3) Incorporation of modifications in SCICHEM version 1601 (January 2004 release) Young & Boris chemistry solver

Application to Central California Central California Ozone Study (CCOS) Ozone episode: July 30 to August 1, 2000 Study domain –185 x 185 grid cells –Horizontal grid resolution of 4 km –20 layers from surface to tropopause (surface layer ~ 30 m)

Features of July/August 2000 CCOS episode Observed peak ozone during the modeling period was 134 ppb at San Andreas station on August 1, 2000 Prevailing winds from the coast to the Central Valley Wildfires in the southeast (Tulare County near the Sierra Nevada)

Model Inputs Meteorology driven by MM5 CMAQ emissions, initial and boundary conditions from CAMx files (ARB) 3-D gridded emissions using SMOKE plume rise processor Ten largest NO x emitting plants (with 56 stacks) selected for plume-in-grid (PiG) treatment

PiG Sources Top 10 NO x emissions 1.Pittsburg power plant (16 Mg/day NO x ) 2.Riverside Cement 3.California Cement 4.Moss Landing power plant 5.Martinez refinery 6.Hanson Cement 7.Unknown 8.Portland Cement 9.IMC Chemicals 10.Contra Costa power plant Total = 101 Mg/day (4% of domain-wide NO x emissions)

Simulations CMAQ base simulation –All emissions in domain in 3-D gridded format CMAQ background simulation –3-D gridded emissions without PiG sources CMAQ-APT simulation –3-D gridded emissions other than PiG sources –PiG sources treated separately with SCICHEM

Extended San Francisco Bay Area

CMAQ Base: Surface Ozone 3 p.m. PDT on July 30, 2000

(Base – Background) Surface Ozone 3 p.m. PDT on July 30, 2000

(APT – Base) Surface Ozone 3 p.m. PDT on July 30, 2000

Evolution of Plume Chemistry Early Plume Dispersion NO/NO 2 /O 3 chemistry 1 2 Mid-range Plume Dispersion Reduced VOC/NO x /O 3 chemistry — acid formation from OH and NO 3 /N 2 O 5 chemistry Long-range Plume Dispersion 3 Full VOC/NO x /O 3 chemistry — acid and O 3 formation

CMAQ Base: Surface HNO 3 3 p.m. PDT on July 31, 2000

(Base – Background) Surface HNO 3 3 p.m. PDT on July 31, 2000

(APT – Base) Surface HNO 3 3 p.m. PDT on July 31, 2000

Comparison of CMAQ-APT results in CCOS and NARSTO CCOS –APT produces up to 10 ppb lower ozone than Base and up to 1.5 ppb lower HNO 3 NARSTO –APT produces up to 40 ppb lower ozone than Base and up to 24 ppb lower HNO 3 (Karamchandani et al., J. Geophys. Res.,107, 4403, 2002) NO x emissions from PiG sources are about 50 times higher in NARSTO than in CCOS

Conclusions CMAQ-APT applied to July/August 2000 CCOS episode O 3 concentrations using APT show both decrements (up to 10 ppb) and increments (up to 6 ppb) with respect to the base The VOC vs. NO x limited nature of the background environment explains the differences in O 3 production and destruction between the APT and base results

Conclusions Surface HNO 3 concentrations are up to 1.5 ppb (about 10%) lower in the CCOS APT simulation and 24 ppb lower in the NARSTO APT simulation, compared to the base cases Effect of PiG treatment on HNO 3 is important for PM nitrate and regional haze modeling. PiG treatment for PM (CMAQ-MADRID-APT) is currently being tested (Karamchandani et al., AWMA, October 2004)

Acknowledgements California Energy Commission California Air Resources Board EPRI Titan/ARAP