1. A study of process contributions to PM 2.5 formation during the 2004 ICARTT period using the Eta-CMAQ forecast model over the eastern U.S. Shaocai Yu $, Rohit Mathur +, Kenneth Schere +, Daiwen Kang $, Jonathan Pleim +, Jeffrey Young +, and Daniel Tong $ 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. 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

6. Tracks of (a) P-3, (b) DC-8 P-3 DC-8 P-3: Northeast ; DC-8: Eastern US

7.  Results: Operational evaluation at AIRNOW sites  Significant underprediction (7/16-7/24)  due to inadequate representation of biomass burning effects from outside the domain (Alaskan fire)

8.  Results (PM 2.5 forecast) 7/19/04 7/18/047/17/04 July 16-22, 2004: Evidence of effects of long range transport (Alaskan fire) (1) MODIS (satellite) observations for AOD (2) TOMS (satellite) observations for absorbing aerosol index  Significant underpredictions of PM 2.5 by the model during July 16 to 26 are mainly due to inadequate representation of biomass burning (carbonaceous aerosol) effects from outside the domain (Alaskan fire)

9.  Results (PM 2.5 Composition at IMPROVE, STN, CASTNET)  PM2.5 under prediction  Overpredicted SO 4 2-  Scatter for NO 3 -  The model under predicted OC by more than a factor of 2  Cause underprediction of PM 2.5 PM 2.5 SO 4 2- NH 4 + NO 3 - EC OC, TC Observation Model

10.  Results ( PM 2.5 composition )  The model overpredicted SO 4 2- by 20%  The model under predicted OC by more than a factor of 2  Cause under prediction of PM 2.5 IMPROVE STN ObsModelObsModel

11.  Results (PM 2.5 ): vertical profiles  Over predicted SO 4 2- aloft  under predicted NH 4 + and NO 3 -

12.  Results ( Vertical profiles for SO 2 and H 2 O 2 )  The model overpredicted SO 4 2- both at the surface and aloft,  in part, possibly reflecting the too much SO 2 cloud oxidation because of overpredictions of both SO 2 and H 2 O 2 in the model. Daily Layer Means (1) P-3 (2) DC-8 SO 2 :  Close to obs at high altitude  Higher than obs at low altitude relative to P3 obs (3) DC-8

13.  Results : HNO 3, and O 3 Vertical profiles (7/1-8/15) HNO 3 :  good at high altitude (1) P-3 Daily Layer Means (2) DC-8 O 3 :  good at low altitude  Overprediction  at high altitudes (3) P-3 (4) DC-8

14.  Preliminary results: PA along the back trajectories  Primary PM 2.5 and SO 2 sources: Washington, DC/NY/Boston urban corridor, Ohio River valley, Chicago  PM 2.5 >38  g m -3 : two sites in PA (8/17) South Allegheny High School John two sites in GA (8/18) South Dekalb Newnan SAHS John SD Newnan

15.  PA Results for PM 2.5  Column mean: layers 1-14 ( typical daytime boundary layer )  At SAHS: CLD and AERO productions as airmass travels over Ohio valley contribute to higher PM 2.5 on 8/17 24-hr back trajectories ending at 11 UTC 8/17

16.  PA Results for PM 2.5  Column mean: layers 1-14 At John site: CLD and AERO productions as airmass travels over Ohio valley contribute to higher PM 2.5 on 8/17

17.  PA Results for PM 2.5  Column mean: layers 1-14  At NN site: AERO and EMIS production as airmass travels over AL, MS, LA contributes to high PM 2.5 24 hr back trajectories ending at 11 UTC 8/19

18.  PA Results for PM 2.5  Column mean: layers 1-14 AT SD site: AERO and EMIS contribute to high PM2.5 as airmass travels over AL and MS, while HADV is the dominant sink

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

21.  Results Layer conc. Of PM 2.5 at NN, SD (GA)

22.  Results : SO 2 and HNO 3 Vertical profiles (3) P-3 (HNO 3 ) (4) DC-8 (HNO 3 ) HNO 3 :  Good performance Except  P3: 7/9, 8/11  DC-8: 7/18 (1) P-3 (SO 2 ) (2) DC-8 (SO 2 ) SO 2 :  Close to obs at high altitude  Higher than obs at low altitude most of time.

23.  Results : O 3 Vertical profiles Model reproduced obs at low altitude and more uniform Except: DC-8: 7/28, 8/11 P-3 : 7/9, 7/15, 7/20-22, 7/28, 8/14 (1) DC-8 (2) P-3

24.  Results : O 3 Vertical profiles  Lidar: Model reproduced obs magnitude at low altitude but smoother distribution  Ozonesonde: Over predictions above 6 km: Impact from GFS derived LBC and coarse model resolution in FT Obs 6km (2) July-August Median Profiles (Ozonesonde) (1) Lidar on Ship Model