A detailed evaluation of the WRF-CMAQ forecast model performance for O3, and PM2.5 during the 2006 TexAQS/GoMACCS study

Shaocai Yu$, Rohit Mathur+, Daiwen Kang$, Jonathan Pleim+, Daniel Tong$, Brian Eder+ and Kenneth Schere+

Atmospheric Sciences Modeling DivisionNERL, U.S. EPA, RTP, NC 27711.

$ On assignment from Science and Technology Corporation + On assignment from Air Resources Laboratory, NOAA

Introduction

Introduction

O3, PM2.5 (d< 2.5 mm) forecast

Necessary (major concern in U.S.)O3: a secondary pollutant PM2.5: primary and secondary pollutantproduced by natural and human activities and photo-chemical reactions adversely affects human health and visibility

Warn the public: unhealthy air voluntarily reduce emission-producing activities

Forecasting methods (EPA, 1999):Persistence, climatology, regression equation etc.3-D air quality models: Spatial and temporal distributions Understand chemical-physical processes controlling O3 and PM2.5 formation

CMAQCommunity Multiscale Air Quality Model

Community Model

Multiscale

consistent model structures for interaction of urban through Continental scales

Multi-pollutant

ozone, speciated particulate matter, visibility, acid depositionand air toxics

Objectives

Comprehensively examine the ability of WRF-CMAQ in representing chemical-physical processes for O3, PM2.5 chemical composition (SO42-, NO3-, and NH4+), and their gas precursors with 2006 TexAQS/GoMACCS and PAMS data

Evaluate 3-D WRF-CMAQ model performance on the spatial and temporal variations of PM2.5 and O3 with AIRNOW Obs over the eastern US

2006 Texas Air Quality Study/Gulf of Mexico Atmospheric Composition and Climate Study (TexAQS/GoMACCS) Photochemical Assessment Monitoring Stations (PAMS)

Model Description

WRF-CMAQ model:

WRF/NMM forecast model provides meteorological fields for CMAQ CB-4 (version 4.2): photochemical processes Emissions processed using SMOKE processing system12 km horizontal grid resolution 22 Vertical layers between surface and 100 mb

2006 TexAQS Period: August 1 to October 15, 2006Using results: 12 UTC WRF simulation cycle run

166142268 grid cells259gridcellsNortheast1x DomainEast 3x Domain Testing Domain: Summer 2006Experimental: CONUS 5X442 grid cells265gridcellsOperational: EUS 3xCONUS 5x DomainThis Study

Observations

EPA AIRNOW network:Hourly PM2.5 and O3 at 614 sites in eastern US.PAMS dataHourly O3, CO, NO, NO2, NOx, SO2 at 9 urban sites

Tracks of ship Tracks of P-3 flights

Observations

TexAQS/GoMACCS DataVertical profiles (O3, HNO3, SO2, H2O2, PM2.5 (SO42-, NO3-, NH4+)) (aircraft (P-3))Ocean data (O3, NO2, NOy, CO, SO2, isoprene, HCHO, toluene) on Ron Brown ship

Results: Operational evaluation for O3 at AIRNOW sites overprediction (8/25-9/30)Very low O3 concentrations

ObsModelUnderprediction: high conc. range

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Decreasing trend67

Increasing trend33

Decrease 67%

Increase 33%

Significant 15.4%

Results: Operational evaluation for PM2.5 at AIRNOW sites due to underestimation of SO42-, NH4+ (see later)Mean:Underpredicted obs PM2.5 by 16%Significant underprediction (8/1-8/31)

Obs11.77.9Mod9.96.6

Obs11.77.9Mod9.96.6

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Decreasing trend67

Increasing trend33

Decrease 67%

Increase 33%

Significant 15.4%

Results: Time-series evaluation with shipGas speciesover Gulf of Mexico

O3Model37.82Obs35.04NO2Model11.07Obs6.14NOyModel15.91Obs10.28COModel129.61Obs122.48SO2Model2.11Obs3.32ISOPModel0.23Obs0.28HCHOModel2.39Obs1.82TOLModel0.30Obs0.50ALDModel2.02Obs1.07

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Decreasing trend67

Increasing trend33

Decrease 67%

Increase 33%

Significant 15.4%

Meteorological parametersResults: Time-series evaluation with ship dataModel underestimated SO42-, NH4+, NO3- by -29, -41, -86%, respectively over Gulf of MexicoMean

TempObs28.9 Model28.7WDIR10Obs167.4 Model164.3WSPD10Obs3.6 Model3.9RGRNDObs461.8 Model466.2

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Decreasing trend67

Increasing trend33

Decrease 67%

Increase 33%

Significant 15.4%

Results (PM2.5 SO42-, NH4+): vertical profilesOver predicted SO42- aloft but under prediction at surface CB-4 chemical mechanism produces too much H2O2 (Yu et al., 2007)Layer means for model and observations from the aircraft (P3) during the 2006 TexAQS/GoMACCS The model under predicted NH4+ both at the surface and aloft, Daily Layer Means

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Decreasing trend67

Increasing trend33

Decrease 67%

Increase 33%

Significant 15.4%

Results (Vertical profiles for O3,CO and SO2 )Daily Layer MeansSO2:Close to obs at high altitudeHigher than obs at low altitudeO3: good at low altitudeOverprediction at high altitudesCO: good at low altitudeUnder-prediction at high altitudes

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Decreasing trend67

Increasing trend33

Decrease 67%

Increase 33%

Significant 15.4%

Daily Layer MeansResults (Vertical profiles for NOy, NO2 and NO )NOy, NO2, NO and HNO3:

Generally good at high altitudesOverprediction at low altitudes

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Decreasing trend67

Increasing trend33

Decrease 67%

Increase 33%

Significant 15.4%

Acetaldehyde:overprediction

Daily Layer MeansToluene, Isoprene: underestimation Results (Vertical profiles of VOC species)

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Decreasing trend67

Increasing trend33

Decrease 67%

Increase 33%

Significant 15.4%

Site 1 (Washington, D.C.)Results: Time-series evaluation at PAMS sites

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Decreasing trend67

Increasing trend33

Decrease 67%

Increase 33%

Significant 15.4%

Results: summary at 4 sites and all 9 PAMS sites

site1234Total O3Obs22.415.523.217.021.8 Model26.828.138.018.632.7 NMB 208163950COObs1020.4276.3301.2319.9379.4 Model423.5333.6186.8351.9275.8 NMB-5821-3810-27NOObs19.618.614.613.913.3 Model5.35.41.215.55.8 NMB-73-71-9211-56NO2Obs13.519.514.815.913.7 Model24.222.010.730.315.6 NMB7913-279114NOxObs33.136.025.929.824.6 Model29.527.111.745.820.5 NMB-11-25-5554-16SO2Obs3.24.28.72.34.7 Model10.48.22.611.86.8 NMB22493-7040744

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Decreasing trend67

Increasing trend33

Decrease 67%

Increase 33%

Significant 15.4%

Contacts:Brian K. Eder

email: eder@hpcc.epa.gov

www.arl.noaa.gov/

www.epa.gov/asmdnerl

Conclusions

Model was able to reproduce the day to day variations in O3 and PM2.5 at AIRnow sitesOverprediction of O3 from 8/25 to 9/30 due to low conc.Under-predicted PM2.5 by 16%, especially from 8/1 to 8/31Due to under-prediction of SO42- and NH4+ Over the Gulf of Mexico on ship:Good for O3 and CO, but underestimated SO2, isoprene and toluene by >20%, and overestimated NO2, NOy and acetaldehyde by >50%. underestimated SO42-, NH4+, NO3- by -29, -41, -86%, respectively

Contacts:Brian K. Eder

email: eder@hpcc.epa.gov

www.arl.noaa.gov/

www.epa.gov/asmdnerl

Conclusions (Continued)

Vertical profiles (P3): Overpredicted SO42- aloft but underestimated at the surface, underestimated NH4+ at both aloft and surface.CB-4 chemical mechanism produces too much H2O2 for SO42-Low altitudes: good for O3, CO, overestimation for NO2, NOy, NO, HNO3High altitudes: good for NO2, NOy,HNO3, SO2, overestimation for O3, acetaldehydeToluene and isoprene: underestimation from low to high altitudes

PAMS 9 surface sites: The model performance varied from site to site for different species:Generally overpredicted O3, NO2, SO2, but underpredicted CO, NO and NOx.

DisclaimerThe research presented here was performed under the Memorandum of Understanding between the U.S. Environmental Protection Agency (EPA) and the U.S. Department of Commerce's National Oceanic and Atmospheric Administration (NOAA) and under agreement number DW13921548. This work constitutes a contribution to the NOAA Air Quality Program. Although it has been reviewed by EPA and NOAA and approved for publication, it does not necessarily reflect their policies or views.

Site 2Results: Time-series evaluation at PAMS sites

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Decreasing trend67

Increasing trend33

Decrease 67%

Increase 33%

Significant 15.4%

Results: Total sulfur during 2004 ICARTTResults (preliminary): Time-series evaluation at PAMS sitesMeanSO2: very scatter, over-predict low conc. but under-predict high conc.

Obs4.65NMM5.94ARW6.85

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Decreasing trend67

Increasing trend33

Decrease 67%

Increase 33%

Significant 15.4%

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Decreasing trend67

Increasing trend33

Decrease 67%

Increase 33%

Significant 15.4%

Results: O3 Vertical profilesSulfur Dioxide 2002 Summer 12-km Eastern USResults: Standard CMAQ performance for SO2

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Decreasing trend67

Increasing trend33

Decrease 67%

Increase 33%

Significant 15.4%

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Change ( /46 years)

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Decreasing trend67

Increasing trend33

Decrease 67%

Increase 33%

Significant 15.4%