Evaluation of CAMx: Issues Related to Sectional Models

1. Evaluation of CAMx: Issues Related to Sectional Models Ralph Morris, Bonyoung Koo, Steve Lau and Greg Yarwood ENVIRON International Corporation Novato, CA (rmorris@environcorp.com) Chao-Jung Chien, Gail Tonnesen and Zion Wang UCR CE-CERT PM Model Performance Workshop Research Triangle Park, North Carolina February 10-11, 2004

2. Outline • Development of CAMx4+ that combines CAMx4 with PMCAMx • Mechanism 4 (M4) 2-Section treatment (fine/coarse) • PMCAMx N-Section treatment • Effects of sectional treatment on nitrate in SoCal • Multi-Model Intercomparison using WUSA 1996 • CMAQ, REMSAD, CAMx_M4 (2-Section) and CAMx N-Section • Discussion of performance metrics • Which ones most appropriate for PM modeling • How to present model performance statistics • Model performance for dummies

3. Science Options in CAMx4+ • PM Size treatment • M4 2-Section (fine/coarse) all secondary PM is fine • N-Section (CMU treatment) • Aerosol Dynamics • ISORROPIA equilibrium (M4 must use) • MADM dynamic • HYBRID • Aqueous-Phase Chemistry • RADM bulk 1-section (M4 must use) • VSRM (CMU multi-section module)

4. Effects of Particle Size Distribution • Testing of assumptions of particle size distribution using new merged CAMx4/PMCAMX code (CAMx4+) • M4 = CAMx4 2-Section plus RADM aqueous • EQUI = N-Sections equilibrium + VRSM aqueous • MADM = 10-Sections dynamic + VRSM aqueous • RADM/EQ = 10-Sections equil. + RADM aqueous • RADM/EQ4 = 4-Sections equil. + RADM aqueous • October 17-18, 1995 Southern California Episode

5. 24-Hour Sulfate (g/m3) • October 18, 1995 • M4 peak SO4 39 g/m3 • EQUI peak SO4 51 g/m3 • ~ Long Beach Area • Differences due to more sulfate production in CMU VRSM than RADM aqueous-phase chemistry • Further downwind (Riverside) M4 produces more sulfate than EQUI M4 EQUI

6. 24-Hour Nitrate (g/m3) • October 18, 1995 • M4 peak NO3 83 g/m3 • EQUI peak NO3 54 g/m3 • Observed NO3 peak at Riverside ~40 g/m3 • Differences due to assuming all nitrate is fine vs. PM nitrate represented by 10 size sections (EQUI) M4 EQUI

7. M4 - EQUI • 24-Hour Nitrate (g/m3) • October 18, 1995 • M4 peak NO3 83 g/m3 • EQUI peak NO3 51 g/m3 • EQUI 10-Section dry deposits NO3 faster due to coarse mode resulting in less NO3 in downwind Riverside area that agrees better with observations •  Raises questions regarding CAMx_M4 & CMAQ assumption that all secondary PM is fine M4

8. 1996 Regional PM Modeling of Western US • WRAP Section 309 SIP modeling used 1996 36 km WUSA Database • 1996 MM5 Simulation (Olerud) • 1996 Base Case Emissions (UNC/UCR) • 1996 Base Case Modeling using CMAQ and REMSAD • Old (~2001) version of CMAQ • Many updates to emissions as part of Section 309 modeling • Use 1996 database to evaluate updates • Model updates CMAQ, REMSAD, CAMx • Emission Updates

9. 1996 Regional PM Modeling • Three models to Intercompare and Evaluate • CMAQ Version 4.3 (August 2003) • REMSAD Version 7.06 • CAMx Version 4+ • Develop Processors to Facilitate Intercomparison • CMAQ-to-REMSAD Emissions, IC, and BC Processors • CMAQ-to-CAMx Emissions, IC and BC Processors • Use CMAQ plume rise estimated in 3-D emission files • Substantial reduction in size of emission inputs • 3-D CMAQ files to 2-D plus (i,j,k) data

10. Science Algorithms Selected for 1996 Modeling

11. Notes on Science Summary of PM Models • CMAQ, CAMx_M4 & CAMx_4Sec all used RADM Aqueous-Phase Chemistry • CAMx_4Sec (N-Section) can also use CMU VRSM, but more computationally demanding • All models used equilibrium (ISORROPIA) approach • Dynamic and Hybrid available in CAMx4+ but computationally demanding • All models configured with CB4 Chemistry • REMSAD uses Micro-CB4 • Some changes in rates, especially Nitrate chemistry

12. Modal vs. Sectional Size Approaches Three Modes: Ten Sections: Although can integrate modal distribution in CMAQ to get PM2.5, in practice usually assume first two modes make up PM 2.5

13. Old CMAQ/REMSAD SO4 PerformanceSec 309 Old CMAQ = V0301 Early 2001New CMAQ = V4.3 August 2003 + MCIP2.2 October 2003 WRAP MF Meeting Improvements in CMAQ Performance using new version

14. 1996 Revised Evaluation – Western USA • January/July Comparisons w/ 4 Models • CMAQ V4.3 • REMSAD • CAMx_M4 • CAMx_4Sec • (F) = All coarse mode PM in CM • (C) = All Secondary PM is Fine • IMPROVE Network (~50 Sites in WUSA & 1996) • Only PM2.5 is speciated • CAMx-4Sec (F) & (C) comparisons can address secondary PM coarse mode issues

15. Revised WRAP 1996 CMAQ Modeling 95 x 85 36 km Grids EPA 1996 MM5 Simulation 18 Vertical Layers MCIP2.2, MM5REMSAD and MM5CAMx Processing of MM5 CB4 Chemistry

16. SO4 IMPROVE – January 1996 CMAQ Red CMAQ RedREMSAD Blue CAMx_M4 Blue

17. SO4 IMPROVE – January 1996 CMAQ Red CMAQ RedCAMx_4Sec (F) CAMx_4Sec (C)

18. SO4 IMPROVE – July 1996 CMAQ Red CMAQ RedREMSAD Blue CAMx_M4 Blue

19. SO4 IMPROVE – July 1996 CMAQ Red CMAQ RedCAMx_4Sec (F) CAMx_4Sec (C)

20. SO4 Time Series • Grand Canyon NP • CMAQ & REMSAD OBS = Red 1996 Annual • CMAQ & CAMx_M4 Models Exhibit Similar Behavior, e.g., Miss Observed High SO4 in Mid-June

21. NO3 IMPROVE – January 1996 CMAQ Red CMAQ RedREMSAD Blue CAMx_M4 Blue

22. NO3 IMPROVE – January 1996 CMAQ Red CMAQ RedCAMx_4Sec (F) CAMx_4Sec (C)

23. NO3 IMPROVE – July 1996 CMAQ Red CMAQ RedREMSAD Blue CAMx_M4 Blue

24. NO3 IMPROVE – July 1996 CMAQ Red CMAQ RedCAMx_4Sec (F) CAMx_4Sec (C)

25. NO3 Time Series • Grand Canyon NP • CMAQ & REMSAD OBS = Red 1996 Annual • CMAQ & CAMx_M4 Models Exhibit Similar Behavior, e.g., Underestimate Summer Observed NO3

26. OC IMPROVE – 1996 Annual CMAQ Red CMAQ RedREMSAD Blue CAMx_M4 Blue

27. EC IMPROVE – 1996 Annual CMAQ Red CMAQ RedREMSAD Blue CAMx_M4 Blue

28. Soil IMPROVE – 1996 Annual CMAQ Red CMAQ RedREMSAD Blue CAMx_M4 Blue

29. CM IMPROVE – 1996 Annual CMAQ Red CMAQ RedREMSAD Blue CAMx_M4 Blue

30. Presentation of PM Model Performance • Need to evaluate on a PM component basis (total PM mass or extinction doesn’t cut it) • Many networks using different instrumentation and species definitions so should not mix networks • Many statistical measures available that often give conflicting signals, which ones should we stress? • Subregional model performance needed • Interested in low as well as high values • No real PM benchmarks available • Results in tables of of numbers that are difficult to interpret and impossible to read

31. Presentation of PM Model Performance • Example Summary Model Performance plots for 1996 WUSA PM Model Intercomparison • Plot Bias versus Gross Error (borrowed from TCEQ) • Compare with Each Other and with Performance “Benchmarks” – Example “Benchmarks” used: • 15% Bias and 35% Error (15%/35%) [borrowed from ozone modeling] • 50% Bias and 75% Error (50%/75%) • Not suggesting these be the benchmarks, used for example purposes only

32. Presentation of PM Model Performance • Mean Normalized Bias Error (MNBE) • Mean Fractional Bias Error (MFBE) • Normalized Mean Bias Error (NMBE) NMBE = Absolute Bias/Average Observed

33. SO4 IMPROVE January 1996

34. SO4 IMPROVE July 1996

35. NO3 IMPROVE January 1996

36. NO3 IMPROVE July 1996

37. Organic Carbon (OC) IMPROVE January 1996 July 1996

38. Elemental Carbon (EC) IMPROVE January 1996 July 1996

39. Preliminary Conclusions 1996 WUSA Modeling • Although models exhibit variations in model performance, no one model is clearly performing better than the others across all species and periods • Model performance in revised 1996 Base Case simulations much improved over previous runs • Improved MM5 processing (e.g., MCIP2.2) • Improved model formulations (e.g., CMAQ V4.3, CAMx3+, REMSAD V7) • Model performance still less than stellar and varies by species and time period • 1996 MM5 simulation has issues • CAMx_4Sec run without NaCl estimate approximately 10% secondary PM is coarse (e.g., 12% SO4 across the WUSA IMPROVE network)