1. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Data Needs for Evaluation of Radical and NOy Budgets in SCOS97-NARSTO Air Quality Model Simulations February 14, 2001, SCOS97-NARSTO DataWorkshop Gail S. Tonnesen University of California, Riverside Bourns College of Engineering Center for Environmental Research and Technology

2. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Acknowledgments Funding for related projects –U.S. EPA –American Chemistry Council Datasets – Draft prerelease datasets provided by ARB

3. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Trace Gas Governing Equations j=1,N Coupled PDEs  C j  t   v.  C j + D  2 C j + P(C)  L(C)C j + E j  D j Operator Splitting:  C j  t =  v.  C j  C j  t = D  2 C j + E j  D j dC j  dt = P(C)  L(C)C j Gear solver is the gold standard for stiff ODEs

4. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Model Evaluation Verification, Validation or Evaluation? –Oreskes et al., 1994. Comparisons with ambient data. Validation of component processes. Indicators for testing O3 sensitivity. Sensitivity and uncertainty analysis.

5. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Family Definitions NO x = NO + NO 2 + (NO 3 + 2 N 2 O 5 + HONO + HNO 4 ) NO z = HNO 3 + RNO 3 + NO 3 – + PAN NO y = NO x + NO z = total oxidized nitrogen. HC = VOC (or ROG) + CH4 + CO O x = O 3 + O + NO 2 + NO z + 2 NO 3 + 3 N 2 O 5 + HNO 4 HO x = OH + HO 2 + RO 2

6. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Fundamental Photochemistry Tropospheric gas phase chemistry is driven by the OH radical: Radical Initiation Radical Propagation Radical Termination NO x termination

7. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside PSS Equilibrium NO 2 + h   NO + O O + O 2  O 3 O 3 + NO  O 2 + NO 2 NO 2 + O 3  NO 3 + O 2 NO 3 + h   NO 2 + O P(O x ): RO 2 + NO  RO + NO 2 HO 2 + NO  OH + NO 2

8. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Radical Initiation O 3 + h   O( 1 D) O( 1 D) + H 2 O  2 OH HCHO + h   2 HO 2 + CO HO 2 + NO  OH + NO 2 HONO + h   OH + NO PAN  RO 3 + NO 2

9. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Radical Propagation OH + CH 4 + O 2  CH 3 O 2 + H 2 O CH 3 O 2 + NO  NO 2 + CH 3 O CH 3 O + O 2  HO 2 + HCHO HO 2 + NO  NO 2 + OH 2x( NO 2 + h  + O 2  O 3 + NO ) Net Reaction: CH 4 + 4 O 2  2 O 3 + HCHO + H 2 O

10. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Radical and NO x termination OH + NO 2  HNO 3 HO 2 + HO 2  H 2 O 2 HO 2 + RO 2  ROOH RO 2 + NO  RNO 3 RO 3 + NO 2  PAN N 2 O 5 + H 2 O  2 HNO 3

11. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside

12. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside

13. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside

14. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Local Diagnostics – Instantaneous reaction rates at a given site. –Examples: P(OH), P(O x ), P(O x )/P(NO z ) –Cannot get production rates from time-series! Cumulative Trajectory Diagnostics –cumulative history of reaction rates and other loss processes in an air parcel integrated over hours or days. –Examples: [H 2 O 2 ], [HNO 3 ], [O 3 ], [O 3 ]/[NO z ] Model Evaluation

15. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Radical Initiation J-values & HCHO, O 3, H 2 O, HONO, H 2 O 2, PAN OH Chain Length  k OH HC i /(  k OH HC i + k OH NO 2 ) k HO2 NO /(k HO2 NO + k HO2 (RO 2 + 2 HO 2 ) ) Radical Termination NO 2 & OH, HO 2 & RO 2, NO & RO 2, O 3 NO x Termination, P(NO z ): NO 2 & OH, NO & RO 2, NO 2 & RCO 3, NO 3, N 2 O 5 & H 2 O P g (O x ) NO, HO 2, RO 2. Data Needs for Local Diagnostics

16. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Radical Initiation & Termination (approximate):Radical Initiation & Termination (approximate): (2 peroxides + NO z ) (2 peroxides + NO z ) OH Chain Length (approximate):OH Chain Length (approximate): O x / (2 peroxides + NO z ) 2 peroxides/NO z 2 peroxides/NO z NO x Termination, P(NO z ):NO x Termination, P(NO z ): HNO 3, speciated RNO 3, NO 3 -, PAN HNO 3, speciated RNO 3, NO 3 -, PAN P(O 3 ), P(O x ):P(O 3 ), P(O x ): O 3, & O 3 +NO 2 + NO z Data Needs for Cumulative Diagnostics

17. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Model Domain and Parameters 1997 Southern California Ozone Study (SCOS97). Aug 3 to 5, 1997 CMAQ and CAMx MM5 16 layers CB4 chemical mechanism Gear CMAQ, CMC CAMx Bott Advection Scheme No Aerosols Includes process analysis diagnostic outputs.

18. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Uncertainties In CMAQ vs CAMx Comparison Timing in CAMx - are emissions calculated as PST or PDT? Vertical mixing - CAMx has less vertical dispersion in early morning? Emissions - CMAQ may be missing large point sources. Problem with isoprene in CAMx

19. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Peak Model Ozone on Aug 5 (3rd day) Difficult to analyze effects accumulated over 3 days, so...

20. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Start Evaluation with spinup (1st day) Comparison of O3 at 15:00 PDT:

21. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Comparison of O3 aloft before start of 2d day Errata: all units are ppbV

22. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Pg(Ox) 7:00-8:00 PDT

23. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Pg(Ox) 8:00-9:00 PDT

24. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Pg(Ox) 9:00-10:00 PDT

25. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Pg(Ox) 10:00-11:00 PDT

26. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Pg(Ox) 11:00-12:00 PDT

27. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Cumulative Pg(Ox) 7:00-19:00 PDT

28. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside CO conc. at 9:00 PDT in LA: inversion breaks up 2 hours later in CAMx…is timing of emissions wrong?

29. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Cumulative P(OH) 7:00-19:00 PDT, Aug 3.

30. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside H2O at 12:00 PDT

31. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside % contribution of O1D to OH initiation, cumulative for Aug 3.

32. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside HO2 initiation, cumulative for Aug 3.

33. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside RO2 radical initiation, cumulative for Aug 3.

34. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Reactions of NO3 & O3 with isoprene, cumulative for Aug 3.

35. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Reactions of OH with isoprene, cumulative for Aug 3.

36. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Total new radical initiation, Layer 1, cumulative for Aug 3.

37. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Total OH Production, Layer 1, cumulative for Aug 3.

38. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside HNO3 mixing ratio, 24:00 PDT, Aug 5.

39. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside HNO3 produced by OH+NO2, Layer 1, cumulative for Aug 5.

40. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside HNO3 produced by OH+NO2, Later 3, cumulative for Aug 5.

41. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside HNO3 produced by N2O5+H2O, cumulative for Aug 5.

42. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside E-W Slice through LA, cumulative for Aug 5.

43. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Fraction HNO3 of total NOz, cumulative for Aug 5.

44. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Net Production of PAN, cumulative for Aug 5.

45. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Production of organic nitrates, cumulative for Aug 5.

46. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Total Production of NOz, cumulative for Aug 5.

47. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Ox production efficiency per NOx, cumulative for Aug 5. (Note: regions of gray within red are areas in which P(NOz) is negative).

48. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Indicators to Evaluate O3 Sensitivity Indicators based on HNO 3 or NO z may fail in CAMx simulations due to large contribution of N 2 O 5 +H 2 O to P(HNO 3 ). Alternative: Use indicators based on radical propagation efficiency, O 3 is VOC sensitive for: %HO 2 +NO > 93% %OH+HC < 80%

49. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Indicator of O3 sensitivity: %HO2+NO (cumulative for Aug 5).

50. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Indicator of O3 sensitivity: %OH+HC (cumulative for Aug 5). (Note colormap is inverted)

51. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Conclusions Minor problems with emissions, vertical dispersion and time zone need to be corrected before full evaluation. More serious issue w.r.t. N 2 O 5 chemistry. Uncertainty in fate of NO x is a critical issue for O 3 sensitivity and weekend effects. Validation of HO x budgets is equally important.

52. Center for Environmental Research and Technology/Environmental Modeling University of California at Riverside Recommendations Should adopt an up-to-date mechanism –SAPRC99, CB4-99, RACM2. Use NO y data to better characterize N 2 O 5 chemistry and NO x fate. Use sensitivity studies to evaluate effects of uncertainty in N 2 O 5 chemistry.