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

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

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)

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

M4

EQUI

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

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

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

M4 - EQUI

0

10

20

30

40

50

60

70

80

90

0.01 0.1 1 10

M4

EQUI

MADM

RADM/EQ

Diameter [m]

dM

/dL

og

(D)

[g

/m3]

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

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

REMSADREMSAD CMAQCMAQ CAMx_M4CAMx_M4 CAMx_4SecCAMx_4Sec

Approach Reduced Form 1-Atmosphere 1-Atmosphere Full Science

Gas-Phase Micro-CB4 CB4

[SAPRC99, RADM, CB4-

2002]

CB4

[SAPRC99]

CB4

[SAPRC99]

Inorganic MARS-A ISORROPIA ISORROPIA ISORROPIA

[Dynamic, Hybrid]

Organic Aerosol Yields SORGAM SOAP SOAP

Aqueous Martin (1984) RADM RADM RADM

[VRSM]

Size Fine/Coarse 3-Modes Fine/Coarse 4-section

[N-Section]

Science Algorithms Selected for 1996 Modeling

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

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

Old CMAQ/REMSAD SO4 PerformanceSec 309 Old CMAQ = V0301 Early 2001

New CMAQ = V4.3 August 2003 + MCIP2.2

Mean Normalized Bias _ SO4

-100

0

100

200

300

400

500

1 2 3 4 5 6 7 8 9 10 11 12

Month

(%)

OLD

NEW

October 2003 WRAP MF Meeting

Improvements in CMAQ Performance using new version

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

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

SO4 IMPROVE – January 1996 CMAQ Red CMAQ Red

REMSAD Blue CAMx_M4 Blue

SO4 IMPROVE – January 1996 CMAQ Red CMAQ Red

CAMx_4Sec (F) CAMx_4Sec (C)

SO4 IMPROVE – July 1996CMAQ Red CMAQ Red

REMSAD Blue CAMx_M4 Blue

SO4 IMPROVE – July 1996 CMAQ Red CMAQ Red

CAMx_4Sec (F) CAMx_4Sec (C)

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

NO3 IMPROVE – January 1996 CMAQ Red CMAQ Red

REMSAD Blue CAMx_M4 Blue

NO3 IMPROVE – January 1996 CMAQ Red CMAQ Red

CAMx_4Sec (F) CAMx_4Sec (C)

NO3 IMPROVE – July 1996 CMAQ Red CMAQ Red

REMSAD Blue CAMx_M4 Blue

NO3 IMPROVE – July 1996 CMAQ Red CMAQ Red

CAMx_4Sec (F) CAMx_4Sec (C)

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

OC IMPROVE – 1996 Annual CMAQ Red CMAQ Red

REMSAD Blue CAMx_M4 Blue

EC IMPROVE – 1996 Annual CMAQ Red CMAQ Red

REMSAD Blue CAMx_M4 Blue

Soil IMPROVE – 1996 Annual CMAQ Red CMAQ Red

REMSAD Blue CAMx_M4 Blue

CM IMPROVE – 1996 Annual CMAQ Red CMAQ Red

REMSAD Blue CAMx_M4 Blue

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

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

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

Ni ie o

ioi=1

( ( ,t) - ( ,t))c cx x x 100 % ( ,t)c x

1MNBE =

N

N

li t,ixoct,ixec2

1t,ixoct,ixec

N

1MFBE

SO4 IMPROVE January 1996

SO4 IMPROVE July 1996

NO3 IMPROVE January 1996

NO3 IMPROVE July 1996

Organic Carbon (OC) IMPROVE

January 1996 July 1996

Elemental Carbon (EC) IMPROVE

January 1996 July 1996

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)