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Evaluation of Ozone Forecasts from the Eta-CMAQ Model Suite During the 2002 NEAQS Study

This study evaluates ozone forecasts produced by the Eta-CMAQ model suite during the 2002 New England Air Quality Study (NEAQS). Utilizing observational data, the analysis focuses on model accuracy in predicting ozone levels, examining various source influences such as mobile and point sources. Key findings include the model's ability to reproduce observed peak ozone concentrations and the effects of NOx-sensitive regimes. The research highlights the need for improved estimates of photochemical processes crucial for accurate air quality assessments.

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Evaluation of Ozone Forecasts from the Eta-CMAQ Model Suite During the 2002 NEAQS Study

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  1. 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

  2. Introduction

  3. 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

  4. AIRMAP sites NE Model domain and site locations

  5. 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

  6. 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

  7. NMB (max 8-hr) Model O3 Max 1hr Max 8hr AQS O3 (ppb)

  8. Results3. Time-series eval. O3 NO Harvard Forest NO2 PAN CO NOy 8/11

  9. 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

  10. 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

  11. 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%)

  12. 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

  13. 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

  14. Contacts: Brian K. Eder email: eder@hpcc.epa.gov www.arl.noaa.gov/ www.epa.gov/asmdnerl

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