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 +, Shaocai Yu $, Rohit Mathur +, Daiwen Kang $, Kenneth Schere +, Brian Eder +,Jonathan Pleim +, Brian Eder +, Jonathan Pleim +, Atmospheric Sciences Modeling Division NERL, U.S. EPA, RTP, NC $ On assignment from $ On assignment from Science and Technology Corporation + On assignment from Air Resources Laboratory, NOAA

Introduction

CMAQC ommunity M ultiscale A ir Q uality M odel 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

NE Model domain and site locations AIRMAP sites

ëParrish et al., 1991: Mobile source: CO, NOx Point source (power plants): SO 2, NOx SO2/NOy<1:mobile source SO2/NOy>1:point source ëSites were significantly influenced by polluted plume after 8/11:  mobile and point sources SO2 (CS) SO2 (TF) CO (CS) CO (TF) 8/11

 Results 1. O3 episode (8/6-8/17/2002) Modeled and observed (diamond) O 3 (ppb) (b) NMB=(model-obs)/obs ~45 ppbv O 3 ~110 ppbv O 3

Max 8hr Max 1hr AQS O 3 (ppb) Model O 3 NMB (max 8-hr)

 Results 3. Time-series eval. O3O3 NO NO 2 PAN CO NOy Harvard Forest 8/11

ëHanna et al. (2001): 50% uncertainty in JNO2 40 ppbv (or 20%) uncertainty in max O 3 Model reproduces 64-77% of observed JNO2 within a factor of 1.5  Priority: more accurate determination of JNO2 in model  Results 3. Time-series at AIRMAP sites

 Results 3. O 3 Lidar vertical profiles Obs Model  Extremely tough test: Temporal and 3-D field correctly Model reproduced obs at low altitude and more uniform Over predictions increase with altitude Ship Track

 Results (diagnostic evaluation) ë NO x -sensitive regimes: [O3]/[NOx], Photochemical age: [NOz]/[NOy], O3 production efficiency: [NOz]/[O3] ëArnold et al., 2003: [O3]/[NOx]<14: VOC-sensitive >46: NOx-sensitive ëBoth model and obs: three sites are mainly under strongly NOx- sensitive conditions (>53%)  NOx-sensitive regimes: [O3]/[NOx]

 Results Photochemical age: [NOz]/[NOy] ëArnold et al., 2003: [NO z ]/[NO y ]>0.6: aged NOx plume ëFor daytime (6 to 18 EST) hours: NOz/NOy>0.6CSTFHF Obs82%72%82% Model96%56%87% ëModel and Obs: accumulating O 3 aging the NOx in the similar way. CS TF HF

 Results O 3 production efficiency ë : O 3 -NO z slope ëParrish et al., 1993 : O 3 -NO z slope: ëupper limit of ë : Obs: 8.3 to 10.0 Model: 4.2 to 5.1 NOzëAt rural sites in E US ( Olszyna et al., 1994) : : 5 to 10 NOz O3O3 CS TF HF

Contacts: Brian K. Eder