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Eric Fujita, Robert Keislar, and William Stockwell Desert Research Institute

Weekend/Weekday Ozone Observations in the South Coast Air Basin Sponsored by National Renewable Energy Laboratory and Coordinating Research Council. Eric Fujita, Robert Keislar, and William Stockwell Desert Research Institute University and Community College System of Nevada Reno, Nevada

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Eric Fujita, Robert Keislar, and William Stockwell Desert Research Institute

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  1. Weekend/Weekday Ozone Observationsin the South Coast Air BasinSponsored byNational Renewable Energy Laboratory and Coordinating Research Council Eric Fujita, Robert Keislar, and William Stockwell Desert Research Institute University and Community College System of Nevada Reno, Nevada Weekend/Weekday Ozone Effect Workshop Sacramento, CA April 13, 2000

  2. Ozone Formation Chemistry O HCHO, RCHO 3 n h NO 2 CO, VOC PAN RO 2 HO H O 2 2 HO 2 ROOH from HNO HO 3 2 from RO 2 NO NO 2 n h O 3 Low ROG/NOx NO2 + h = O + NO O + O2 + M = O3 + M O3 + NO = NO2 + O2 High ROG/NOx

  3. NO2* = NOx-NO

  4. CO Versus NMHC from DRI Canister Samples During Summer 1995 and 1996

  5. Heavy-Duty Diesel Hydrocarbon Emission Rates Measured on Chassis Dynamometer from Mid-1970s to Mid-1990s for 4-Stroke Engines Source: Zielinska, 1999 Health Assessment Document for Diesel Emissions: Chapter 2 - Diesel Emissions, atmospheric concentrations, transport and transformation. U.S. EPA Office of Health and Environmental Assessment.

  6. Heavy-Duty Diesel NOx Emission Rates Measured on Chassis Dynamometer from Mid-1970s to Mid-1990s for 4-Stroke Engines Source: Zielinska, 1999 Health Assessment Document for Diesel Emissions: Chapter 2 - Diesel Emissions, atmospheric concentrations, transport and transformation. U.S. EPA Office of Health and Environmental Assessment.

  7. Trends in Federal 1-Hr Exceedances 80s 90s

  8. Factors Affecting High Ozone on Weekends • Overnight NO2/NOx ratios and carryover of NO2 and are similar for WEs and WDs making the potential ozone production about equal for the same level of emissions during the morning commute period. Overnight NO2/NOx ratios and carryover of NO2 are greater in eastern part of the basin. • Greater NO emissions on WD mornings delay O3 accumulation. Delay is greater in western portion of the basin. • Higher overnight CO and ROG and lower NO emissions on WEs result in higher ROG/NOx and ROG/NO2 ratios, which increase the rate of ozone formation. • Where O3(max) occurs before O3(potential max) can be reached, the strength of the WE effect depends upon duration of the ozone accumulation period. • The strength of the WE effect has increased where ROG/NOx ratios have decreased over time. • Duration of the ozone accumulation period has become shorter over time accounting for downward trend in ozone levels, especially in decade of the 90s.

  9. Status of ProjectWeekend/Weekday Ozone Observationsin the South Coast Air BasinDesert Research Institute and Sonoma Technology, Inc. • PHASE I: Retrospective Analysis of Ambient and Emissions Data and Refinement of Hypotheses • Preliminary report due 3/31/00 • Final report 5/31/00 • PHASE II: Field Measurements to Test Hypotheses • Conduct field measurements in SoCAB during summer 2000 • Data Report due 2/28/01 • PHASE III: Data Analysis and Final Report • Draft Reports due 12/15/01 • Synthesis of Results and final report due 2/28/02

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