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Section 11 Case Studies of Episodes

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  1. Section 11Case Studies of Episodes What is a Case Study? How to Conduct Case Studies Examples

  2. What is a Case Study? • Analysis of the causes of an air quality episode • Case studies provide insight into important processes • Components of a case study • Air quality conditions • Weather situation • Summary of episode • Important air quality processes • Important meteorological processes Section 11 – Case Study of Episodes

  3. How to Conduct Case Studies • Select a few air quality episodes to study • Include ramp-up and cleanout days • Review locations, magnitude, and duration of poor air quality • Review surface and upper-air weather patterns • Create backward trajectories to estimate transport • Estimate upwind air quality to quantify local versus background contributions • Review the temperature soundings to estimate vertical mixing • Summarize the important processes that produced the episode Section 11 – Case Study of Episodes

  4. Examples • Each example includes • Location and background • Air quality conditions • Weather situation (surface, upper-air, stability, winds, etc.) • Summary of episode (air quality and meteorology) • Case study examples • PM10 episode • Ozone episode • PM2.5 episode • CO episode • Long-range transport episode • Multi-pollutant episode • Smoke episode Section 11 – Case Study of Episodes

  5. Case Study of PM10 Episode in Cairo, Egypt • Location and background • Air quality conditions • Weather situation • Summary of episode (air quality and meteorology) Section 11 – Case Study of Episodes

  6. Cairo Location – Cairo, Egypt Section 11 – Case Study of Episodes

  7. Air Quality Conditions Time series plot of PM10 concentrations in Cairo in October 1999. The October 20-25, 1999, episode is outlined (Dye et al., 2000). Section 11 – Case Study of Episodes

  8. H Weather Situation (1 of 6) • Surface and upper-air weather patterns 500-mb heights (dm) (solid) and 850-mb temperatures (oC) (dashed) (left), and sea level pressure (mb) and surface wind flags (right) on October 20, 1999, at 1400 LT Section 11 – Case Study of Episodes

  9. L Light northerly winds Weak trough just passed Weather Situation (2 of 6) • Surface and upper-air weather patterns 500-mb heights (dm) (solid) and 850-mb temperatures (oC) (dashed) (left), and sea level pressure (mb) and surface wind flags (right) on October 23, 1999, (high PM day) at 1400 LT Section 11 – Case Study of Episodes

  10. Weather Situation (3 of 6) Moderate northerly winds Strong trough just passed Surface and upper-air weather patterns 500-mb heights (dm) (solid) and 850-mb temperatures (oC) (dashed) (left), and sea level pressure (mb) and surface wind flags (right) on October 25, 1999, (cleanout day) at 1400 LT Section 11 – Case Study of Episodes

  11. 32 20-Oct 21-Oct 22-Oct 23-Oct 31.5 21 24-Oct 25 20 25-Oct 22 31 24 Latitude (degrees) 23 30.5 Short transport on high PM day 30 29.5 29.5 30 30.5 31 31.5 32 32.5 Longitude (degrees) Weather Situation (4 of 6) • Backward trajectories to estimate transport 12-hr backward trajectories ending in Cairo at 1400 LT each day October 20 to 25, 1999. Section 11 – Case Study of Episodes

  12. Weather Situation (5 of 6) • Upper-air nighttime soundings to estimate vertical mixing 0200 LT temperature soundings taken at Helwan from October 20 to 25, 1999. Section 11 – Case Study of Episodes

  13. Warming Height (m) 21 22 25 24 20 23 Temperature (ºC) Weather Situation (6 of 6) • Upper-air daytime soundings to estimate vertical mixing 1400 LT temperature soundings taken at Helwan from October 20 to 25, 1999. Section 11 – Case Study of Episodes

  14. Summary of Episode • Episode characteristics • Weak upper-level troughs passed over and north of Egypt • The troughs lowered surface pressures to the north, thereby weakening the northerly winds, but winds still remained light-to-moderate from the north • Aloft temperatures warmed, the capping inversion lowered, and vertical mixing was reduced • Despite the moderately strong northerly winds, the reduced vertical mixing allowed for high PM10 concentrations • The episode ended when a strong trough followed by a ridge passed over Egypt, increasing the northerly winds and weakening the inversion Section 11 – Case Study of Episodes

  15. Examples • GTT – Please provide examples of other case studies • For each example include • Location and background • Air quality conditions • Weather situation (surface, upper-air, stability, winds, etc.) • Summary of episode (air quality and meteorology) • Case study examples • Ozone episode • PM2.5 episode • PM10 episode (done) • CO episode • Long-range transport episode • Multi-pollutant episode • Smoke episode Section 11 – Case Study of Episodes

  16. Case Study of Ozone Episode • Location and background • Air quality conditions • Weather situation • Summary of episode (air quality and meteorology) Section 11 – Case Study of Episodes

  17. Case Study of Ozone Episode • Youngstown, Ohio, USA • Summer 2002 Section 11 – Case Study of Episodes

  18. 24-hr Backward Trajectory Surface Pressure (msl) 500-mb Heights L H L H L L H L H H H H H H H Jun07th12:00 pmEST Jun13th12:00 pmEST Jun11th12:00 pmEST Jun12th12:00 pmEST Jun08th12:00 pmEST Jun09th12:00 pmEST Jun10th12:00 pmEST Case Study of Ozone Episode 9-11 June 2002 Episode Youngstown Regional 8-hr O3 Maximum 160 * 140 * 120 * 100 Maximum AQI 80 * * 60 * * 40 20 0 7-Jun 8-Jun 9-Jun 12-Jun 13-Jun 10-Jun 11-Jun Section 11 – Case Study of Episodes

  19. 24-hr Backward Trajectory Surface Pressure (msl) 500-mb Heights L H H H H H Jul08th12:00 pmEST Jul10th12:00 pmEST Jul06th12:00 pmEST Jul07th12:00 pmEST Jul09th12:00 pmEST Case Study of Ozone Episode * Youngstown Regional 8-hr O3 Maximum * * * * Section 11 – Case Study of Episodes

  20. Summary of Ozone Episodes • Episode characteristics • Ridge of high pressure created high pressure system • Recirculation was important for the 9-11 June and July 8, 2002 • Episodes occurred on weekdays, which typically have higher emission patterns • Trajectories are useful for diagnosing air movement • Transport of ozone from upwind regions contributed to the ozone on 11 June 2002 Section 11 – Case Study of Episodes

  21. AUSTRALIA SYDNEY Case Study of Ozone Episode in Sydney, Australia • Ozone episode Section 11 – Case Study of Episodes

  22. Eg: Syndey O3 Event Dec 1998 Section 11 – Case Study of Episodes

  23. AUSTRALIA MELBOURNE Case Study of Smoke Episode in Melbourne, Australia • Smoke episode Section 11 – Case Study of Episodes

  24. Case Study of Smoke Episode in Melbourne, Australia Section 11 – Case Study of Episodes

  25. Case Study of Smoke Episode in Melbourne, Australia • Visible satellite image and modeled smoke Section 11 – Case Study of Episodes

  26. How to Conduct Case Studies • Select a few air quality episodes to study • Include ramp-up and cleanout days • Review locations, magnitude, and duration of poor air quality • Review surface and upper-air weather patterns • Create backward trajectories to estimate transport • Estimate upwind air quality to quantify local versus background contributions • Review the temperature soundings to estimate vertical mixing • Summarize the important processes that produced the episode Section 11 – Case Study of Episodes