1. Ozone Budget From: Jacob

2. Ozone in the Atmosphere Lifetime: –~1 month –Highly variable – dependent on season, latitude, altitude, etc. Background concentrations: –less than 40 ppbv –can reach over 200 ppb in urban areas

3. Ozone in the Atmosphere From: Fishman et al., 2005, Atmos. Chem Phys. Discuss., 3, 1453

4. HO x Sources and Sinks Source: oxidation of VOCs: Sinks:

5. HO x Cycle

6. HO x in the Atmosphere Lifetime: –~1 second –highly variable (same reasons as for O 3 ) Typical concentrations: –~5 x 10 6 molecules/cm 3 –higher over oceans and southern hemisphere less anthropogenic CO and methane

7. NO x Sources and Sinks Sinks: From: Jacob

8. Nighttime NO x Chemistry There is no NO at night: sink -when the sun comes up

9. Peroxyacetylnitrates (PANs) Organic radicals of the form: RO ROO R(O)OO can sequester NO 2. The most common is PAN: CH 3 C(O)OONO 2.

10. NO x Cycle

11. NO x in the Atmosphere The lifetime of NO x varies, but is about 1 day near the surface and about 1 week in the upper troposphere. Concentrations range from a few pptv to 10’s of pptv. –higher concentrations near the ground. Urban areas may reach concentrations of 10s of ppbv.

12. NOx in the Atmosphere From: Lamsal et al., 2008, J. Geophys. Res., 113, D16308, doi:10.1029/2007JD009235

13. CO Budget From: Jacob

14. CO in the Atmosphere The lifetime of CO is about 2 months with respect to oxidation by OH CO is not well mixed globally –remote concentrations: 50-150 ppbv –over populated continental regions: 100-300 ppbv –in urban centers: > 1ppmv

15. CO in the Atmosphere From: Barret et al., 2005, Atmos. Chem Phys. Discuss., 5, 4599

16. CO in the Atmosphere

17. Methane Budget From: Jacob

18. Methane in the Atmosphere The overall lifetime of methane is 8.5 yrs. Current concentrations are about 1.8ppmv. –up from 800 ppbv preindustrial –methane and CO 2 concentrations track each other over geological time periods.

19. Methane in the Atmosphere

21. Beyond CO and Methane There are literally thousands of volatile organic compounds (VOCs) present in the atmosphere in trace amounts (pptv-ppbv). Many have short lifetimes –Low concentrations –Big influence on chemistry

22. Biogenic VOCs Terpene compounds are emitted by trees: Isoprene Monoterpene Sesquiterpene

23. Biogenic VOCs Globally, about 80% of VOCs emitted to the atmosphere are biogenic. Anthropogenic VOCs dominate only in industrial or some urban areas.

24. Photochemical Smog

25. O3O3 OH RO 2 RO HO 2 H2O2H2O2 HNO 3 O3O3 O3O3 P HOx k1k1 k2k2 k3k3 k4k4 k5k5 k6k6

26. Photochemical Smog

27. Case 1: Low NO x -O 3 production varies linearly with NO x -independent of hydrocarbons NO x -limited regime

28. Case 2: High NO x

29. -O 3 production varies linearly with hydrocarbons -varies inversely with NO x Hydrocarbon-limited regime

30. Ozone Pollution From: Jacob

31. Ozone Pollution In the background atmosphere:

32. Ozone Pollution In the urban atmosphere, there is a competition between NO 2 and RH for the OH radical: As a rule of thumb:

33. Why too much O 3 is a bad thing Health effects: –Irritation of the lungs (short exposure to high concentrations). –Permanent lung damage (long-term exposure). –Effects are worst for the elderly and people with asthma. Ecosystem effects: –Reduced photosynthesis (low crop yields). –Increased susceptibility to pests. –Leaf scarring.

34. Ozone Air Quality Standards Federal: –1 hour maximum concentration = 120 ppbv –8 hour average maximum concentration = 75 ppbv State of California: –1 hour maximum concentration = 90 ppbv

35. Ozone Problem Areas From: EPA

36. Air Quality Index From: EPA

37. Air Quality Index

38. Peak Ozone for California From: www.airnow.gov 1 - 50 51 - 100 101 - 150 151 - 200 201 - 250 Data Not Available AQI

39. LA Region Maximum Ozone From: California Air Resources Board

40. LA Region Ozone Exceedance From: California Air Resources Board

41. Sacramento Region Max Ozone From: California Air Resources Board

42. Sacramento Region Annual Ozone From: California Air Resources Board

43. Sacramento Ozone Exceedance From: California Air Resources Board

44. Sacramento Region Ozone Ozone data from: California Air Resources Board

45. 1 - 50 51 - 100 101 - 150 151 - 200 201 - 250 Data Not Available Ozone data from: www.airnow.gov AQI