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Operational and diagnostic evaluations of ozone forecasts by the Eta-CMAQ model suite during the 2002 new England air quality study (NEAQS)

Shaocai Yu$,Rohit Mathur+, Daiwen Kang$,Kenneth Schere+,

Brian Eder+,Jonathan Pleim+,

Atmospheric Sciences Modeling Division

NERL, U.S. EPA, RTP, NC 27711.

$On assignment from Science and Technology Corporation

+ On assignment from Air Resources Laboratory, NOAA

CMAQ Community Multiscale Air QualityModel

- Community Model
- Multiscale
- consistent model structures for interaction of urban through Continental scales
- Multi-pollutant
- ozone, speciated particulate matter, visibility, acid deposition
- and air toxics

AIRMAP sites

NE Model domain and site locations

SO2 (CS)

- Parrish et al., 1991:
- Mobile source: CO, NOx
- Point source (power plants): SO2, NOx
- SO2/NOy<1:mobile source
- SO2/NOy>1:point source

CO (CS)

SO2 (TF)

- Sites were significantly influenced by polluted plume after 8/11:
- mobile and point sources

CO (TF)

8/11

Results1. O3 episode (8/6-8/17/2002)

Modeled and observed (diamond) O3 (ppb)

~45 ppbv O3

~110 ppbv O3

(b) NMB=(model-obs)/obs

Results3. Time-series at AIRMAP sites

- Hanna et al. (2001):
- 50% uncertainty in JNO2
- 40 ppbv (or 20%) uncertainty in max O3
- Model reproduces
- 64-77% of observed JNO2 within a factor of 1.5
- Priority: more accurate determination of JNO2 in model

Results

3. O3 Lidar vertical profiles

Obs

- Extremely tough test:
- Temporal and 3-D field correctly
- Model reproduced obs at low altitude and more uniform
- Over predictions increase with altitude

Model

Ship Track

Results (diagnostic evaluation)

- NOx-sensitive regimes: [O3]/[NOx], Photochemical age: [NOz]/[NOy],

O3 production efficiency: [NOz]/[O3]

- NOx-sensitive regimes: [O3]/[NOx]

- Arnold et al., 2003:
- [O3]/[NOx]<14:VOC-sensitive
- >46:NOx-sensitive

- Both model and obs: three sites are mainly under strongly NOx-sensitive conditions (>53%)

ResultsPhotochemical age: [NOz]/[NOy]

- Arnold et al., 2003:
- [NOz]/[NOy]>0.6:aged NOx plume

CS

- For daytime (6 to 18 EST) hours:

TF

- Model and Obs: accumulating O3
- aging the NOx
- in the similar way.

HF

Results

O3 production efficiency

- : O3-NOz slope

- Parrish et al., 1993 :
- O3-NOz slope:
- upper limit of
- :
- Obs: 8.3 to 10.0
- Model: 4.2 to 5.1

CS

TF

- At rural sites in E US (Olszyna et al., 1994):
- : 5 to 10

NOz

O3

HF

NOz

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