NOAA National Air Quality Forecast Guidance for Ozone and Particulate MatterDecember 9, 2009Daewon W. Byun1*Hsin-Mu Lin1, Daniel Tong1, Tianfeng Chai1, Ariel Stein1, Roland Draxler1, Hyun-Cheol Kim1, Fantine Ngan1, Pius Lee1, Rick Saylor1, Jeff McQueen2, Youhua Tang2, Jianping Huang2, Hochun Hwang2, Dong-Chul Kim2, Marina Tsidulko2, Rohit Mathur5, George Pouliot5, Shobha Kondragunta4, Jerry Gorline, Ivanka Stajner3, and Paula Davison31NOAA/Air Resources Laboratory2NOAA/NCEP, 3NOAA/OST, 4NOAA/NESDIS5EPA/Atmospheric and Modeling & Analysis Division

OutlineOverview of NOAA National Air Quality Forecasting SystemPerformance of ozone guidancePerformance of experimental PM forecastingFY10 & future developmental plans

*National Air Quality Forecast Capability

Improve model bases for AQ alertsProvide AQ information for people at risk

Near-term Operational Targets:Ozone, smoke coverage extended NationwideWhen NCEP is ready for CONUS 4-km NAM meteorology (NAM-B at 4-km) High resolution AQ prediction (4km) for CONUS

Longer range:Quantitative PM2.5 predictionExtend air quality forecast range to 48-72 hoursInclude broader range of significant pollutantsFY09 Prediction Capabilities: Operations at 12-km resolution: Ozone, expanded from EUS to CONUS, 9/07Smoke implemented over CONUS, 3/07Experimental testing:Ozone upgradesSmoke predictions over Alaska and HawaiiDevelopmental testing: Ozone over AK and HIComponents for particulate matter (PM) forecasts2009: smoke

142NAM-CMAQ NAQFC Current Configuration Ozone production & PM experimental http://www.weather.gov/aqEmissions: EPA CEM anthropogenic inventories 2005 base year projected to current year w/ EGUBEIS V3 Biogenic Emissions

Met Model: North American Model (NMM) Non-hydrostatic Multi-scale Model (NMM)12 km 60 Levels

AQ Model: EPA Community Model For Air QualityCMAQ V4.6: 12 km/L22 CONUS DomainOper: CB-IV gas-phaseExper/Dev: CB05/ Aero-4 aerosolsOutput available on National Digital Guidance Database48 hour forecasts from 06/12 UTC CyclesCONUS 5x DomainEastern US 3x DomainFY 06-07Data and Modeling Systems

Number of observed values higher than 76 ppb threshold 1200 UTC8-h ozone, by regionFewer cases in the East in 2009,compared to 2007 and 2008(except for CA) Performance of O3 forecastJerry Gorline

8-h ozone bias, three-year comparisonAugust 2007, 2008, 2009CONUS, 1200 UTC cycle (48 hour forecast mean) experimental:slightly higher bias in 20092007: CBIV2008: CB052009: CB05Jerry Gorline

NCEP Air Quality Forecast 2009 Verification (1 hr Max ozone for Day 2 for June, July, Aug)- Increasing Bias trend as Summer progressed for Eastern U.S. Max temp bias improves slightly by August but ozone errors increased in East U.S.RMSEBIASCB-IVCB-05*** CB-05 mechanism is used for improving SOA, etc for CMAQ4.7Jeff McQueenEastWest

Sept.Rock Mountain Upper MidwestNortheast USPacific Coast RegionLower MidwestSoutheast US1/1/-9/30 2009

Rock Mountain RegionUpper MidwestNortheast USPacific Coast RegionLower MidwestSoutheast US

Interim summary of NAQFS O3High O3 events decreased considerably 2007 2008 2009 except for CA. Also, CB05 high bias much more serious than CB-IV. CB05 high bias increased in 2009 compared to 2008High bias accumulates in Eastern USWould 2009 economic downturn cause higher model bias due to wrong emission projection (e.g., Bill Ryan)?Causes of CB05 high bias over CB-IV may be ???Addition of terpene emissions make more radicals available affecting formation of PAN species NOY recycling (additional NOx source)Inadequate removal processes (dry & aqueous deposition)Anything else (such as interaction of gas-, aerosol, and heterogeneous reactions)?

How dose PM behaves? Seasonal variation of activity8-h ozone vs. 1-h aerosols (June 2008 to August 2009)Threshold: 76 ppb (ozone) 35 ug/m3 (aerosols)Aerosols are active in both winter and summer

2009 AQFS Performance DevelopmentalPM2.5, US (CB05/Aero4, Daily Max)OBS meanCMAQ meanMean BiasNormalizedMean BiasRMSENormalized Mean ErrorCorrelation(hourly)

Correlation(daily max)1/1/-9/30 2009

Rock Mountain Upper MidwestNortheast USPacific Coast RegionLower MidwestSoutheast US1/1/-9/30 2009

Rock Mcountain RegionUpper MidwestNortheast USPacific Coast RegionLower MidwestSoutheast US

Regional performance of aerosols Fraction Correct (FC) Jan 2008 to Sept 2009, 35 ug/m3lower bias inwinter 2009 compared to winter 2008,except PC regionCB05AERO-41/1/-9/30 2009

Forecast and Obs (1 hr avg) for Oct 31-Nov 30, 2009(48 hour mean forecast vs. Obs)PC region show not much bias in Nov. 2009, but UM shows high bias (~ 10 ug/m3)UM PC Jerry Gorline

Underprediction prevalent in Eastern U. S. on Aug 16

Large area of overprediction by Aug 24

Preliminary SEARCH Data Jefferson St., Atlanta, GARain ?Rick Saylor

Preliminary SEARCH Data Yorkville, GAIntermittent RainRick SaylorComparison with AQFS model speciation output underway..

Investigation of model bias:

Study sulfate production by different mechanisms

Gas phase chemistry: CB-IV, CB05, SAPRC99, CB05 Cloud processes & Aqueous chemistry Scavenging and wet deposition Model domain Eastern US Horizontal: 12-km resolution Vertical: variable thickness 22 layers Study period: 14-23 July, 2004 (ICARRT case) 2004 ICARRTAriel Stein

Differences in Sulfate Production (by mechanism)Backward trajectoriesover source areasVariable & away from large sourcesTotal similar but CB-IV mostly from H2O2 & MHPCB05 & SAPRC show contributions from PE/MN & PAA

H2O2CB-IV formation rate 60% higher than CB05 and SAPRC-99. CB05 produces more new HO2 than SAPRC-99

MethylhydroperoxideCB-IV: XO2 + HO2 MHPCB05: MEO2 +HO2 MEPXMEPX + OH prodMEPX + hn prodHCO3 + HO2 MEPXSAPRC99:C_O2 + HO2 COOHCOOH + OH prodCOOH + hn prodobsMHP from CB-IV seriously over estimatedMEPX from CB05 & COOH from SAPRC well predicted butAriel Stein

CBIV: PACD well predictedPA + HO2 prod + 0.21 PACDPeroxyacetic acidSAPRC-99:PAA overpredictedPA + HO2 prod + 0.75 PAACB05:PACD overpredictedPA + HO2 prod + 0.8 PACDPACD + OH PACXO3 + HO2 prod +0.8 PACD

On-going work Include Fire Emissions: Link NESDIS HMS/USDA Bluesky/ARL HYSPLIT inputCMAQ ModelChemical-Transport ComputationNCEP Meteorological Model (NAM)PREMAQEPA Emissions InventoryHMS data & Bluesky(as in HYSPLIT)Fire Emission: EPA inv + Bluesky(CMAQ ready data)Emissions(CMAQ ready data)Met. Data(CMAQ ready data)1st step: Fire event process2nd step: Plume rise processEmission due to the FireHsin-Mu LinAriel Stein

HMS Case for 2009-05-09 1200Z runThe plot show the difference of PM2.5 between the CMAQ with and without Smoke ProductComparison with the satellite fire detection and HYSPLIT PM product are also providedHsin-Mu Lin

PM2.5 bias to observation (small circles) with & without fire emissions(* climatology fire emission is removed from the HMS/BlueSky/HYSPLIT emissions) CMAQ PM2.5 Difference(HMS PARA) in mg/m3Without fire emissions:CMAQ PM2.5 in mg/m3in mg/m3Bias here did not improve with the addition of fire emissions(Colors for circles and background Have no relations)Improved with fire emissionsCase for 2009-08-02(good model prediction if color between circles and background cells are close)Youhwa Tang

Major Dust Emission SourcesEPAs NEI includes anthropogenic dust sources (Road dust, mining, construction, tilting, etc)Anthropogenic sourcesCropland sources Natural dust not accounted for yet in NAQFS Owens flux equation Threshold friction velocities from field and wind tunnel measurements; USGS land use and soil data; Vegetation growth and near source enhanced deposition;Modeling Natural Dust requiresOn-going work to include Wind-Blown Dust EmissionsDust emissions most active in Spring Annual Emissions ~ 3 Tg/yrDaniel Tong

Testing algorithms -- Comparison with IMPROVE & MODIS(April 2003 Case Study)Improved, but not enough. MODISMODELDaniel Tong

NCEP FY10 Plans: Global-Regional LinkagesCMAQ Lateral Boundary Condition Impact Study : GOCART Global model w/ full aerosols (dust, biomass) coupled to CMAQ

Implement Real-time Global Dust Forecasts: Couple w/ para GFS fields to drive GOCART GFS T382-GOCART 1 real-time runs to 60 hours w/ 1 degree surface cover

Develop Chemical Data Assimilation & global aerosol interactions : GOCART aerosol analyses coupled to GSI & GFS/CFS radiationOnline NEMS GOCART module Adding AOD tracer to GSIPrefer on-line so forward guess at same timeHo-Chun HwangDong-Chul Kim

Chart8

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-0.37999999520.1655975571

-0.25999999050.23638797

-0.13999998570.3166418152

-0.01999998840.407490715

0.10000000890.5101670456

0.21999999880.6260135269

0.34000000360.7564574966

0.46000000830.9030076522

0.57999998331.0672423782

0.69999998811.2507255325

0.81999999281.455213295

0.93999999761.6825042648

1.0599999431.9352856216

1.1799999482.2163295059

1.2999999522.5262721634

1.4199999572.8652197952

1.5399999623.233355751

1.6599999673.6315365982

1.7799999714.0604526443

1.8999999764.5203245925

2.0199999815.0130516738

2.1399998665.5385679702

2.2599997526.0965226821

2.3799996380.001673567

2.499999523

2.619999409

2.739999294

2.85999918

2.979999065

3.099998951

3.219998837

3.339998722

3.459998608

3.579998493

3.699998379

3.819998264

3.93999815

4.059998035

4.179997921

4.299997807

4.419997692

4.539997578

4.659997463

4.779997349

4.899997234

5.01999712

5.139997005

5.259996891

5.379996777

CALIPSO

MODEL

Aerosol Extinction (1/km)

Hight (km)

-12.6E 14.9N, 2006072214

2006072214a

TIME20060722

LON/LAT-12.6074409514.89016628

1-0.548.318401346.20E-02

2-0.379999995254.906826026.31E-020.1032252274

3-0.259999990562.372329716.35E-020.1655975571

4-0.139999985770.79041296.38E-020.23638797

5-2.00E-0280.253845216.40E-020.3166418152

60.100000008990.848899846.43E-020.407490715

70.2199999988102.67633066.46E-020.5101670456

80.3400000036115.84648136.50E-020.6260135269

90.4600000083130.44396976.55E-020.7564574966

100.5799999833146.55015566.62E-020.9030076522

110.6999999881164.2347266.72E-021.0672423782

120.8199999928183.48315436.89E-021.2507255325

130.9399999976204.48776257.18E-021.455213295

141.059999943227.29096987.63E-021.6825042648

151.179999948252.78135689.20E-021.9352856216

161.299999952281.04388431.09E-012.2163295059

171.419999957309.94265750.12419841442.5262721634

181.539999962338.94763180.13197544222.8652197952

191.659999967368.13595580.11302167183.233355751

201.779999971398.18084727.59E-023.6315365982

211.899999976428.91604615.51E-024.0604526443

222.019999981459.87194821.36E-024.5203245925

232.1399998664.02E-02492.72708133.26E-035.0130516738

242.2599997521.23E-01525.51629642.43E-035.5385679702

252.3799996380.1533277035557.95471191.67E-036.0965226821

262.4999995230.1495400071588.31500241.46E-036.6848376845

272.6199994090.1482252032612.91784671.92E-037.2977555312

282.7399992940.1259313524636.08404542.15E-037.9338395766

292.859999186.40E-02658.55975343.11E-038.59239933

302.9799990659.00E-02676.93493653.15E-039.2693342665

313.0999989511.06E-01692.38183592.07E-039.9617161024

323.2199988379.36E-02704.9495851.54E-0310.6666656874

333.3399987220.1005941257715.9218751.13E-0311.3825875624

343.4599986081.43E-01721.81335451.02E-0312.1044009169

353.5799984939.79E-02722.71752931.25E-0312.8271184462

363.6999983798.73E-02722.63061521.08E-0313.5497490614

373.8199982646.69E-02720.12231457.31E-0414.2698713759

383.939998153.33E-02719.79473885.15E-0414.9896661147

394.059998035726.11718752.65E-0415.7157833022

404.179997921729.66125498.10E-0516.4454445571

414.2999978072.50E-02744.43035894.24E-0517.189874916

424.4199976925.37E-02770.65679933.50E-0517.9605317153

434.5399975788.16E-02801.48309331.33E-0518.7620148086

444.6599974633.72E-02834.63256841.27E-0619.596647377

454.7799973494.37E-02856.87365723.95E-0720.4535210342

464.8999972345.87E-02876.71661389.12E-0821.330237648

475.019997125.47E-02905.40289312.56E-0822.2356405411

485.1399970053.55E-02929.92681885.83E-0923.1655673599

495.2599968911.41E-02962.98529053.96E-0924.1285526504

505.3799967771008.3787233.86E-0925.1369313734

2006072214a

CALIPSO

MODEL

Aerosol Extinction (1/km)

Hight (km)

-12.6E 14.9N, 2006072214

2006072214b

TIME20060722

LON/LAT-14.5997419423.50664139

1-0.548.952407843.30E-01

2-0.379999995255.608718873.23E-010.1045611267

3-0.259999990563.167167663.16E-010.1677282944

4-0.139999985771.691925053.10E-010.2394202194

5-2.00E-0281.272468573.03E-010.320692688

60.10000000890.110337510792.006301882.96E-010.4126989899

70.21999999880.4578230977103.96345522.88E-010.5166624451

80.34000000360.4701274931117.2448732.81E-010.6339073181

90.46000000834.24E-01132.00633242.73E-010.7659136505

100.57999998330.3681202233148.41081242.65E-010.9143244629

110.69999998810.2300999612166.52192692.56E-011.0808463898

120.81999999280.2029348165186.33993532.46E-011.2671863251

130.93999999760.3033529222207.7976992.34E-011.4749840241

141.0599999430.2460214943230.86366272.20E-011.7058476868

151.1799999480.2169344723255.49653632.10E-011.9613442231

161.2999999520.1415001452281.56411741.99E-012.2429083405

171.4199999570.1452540159308.86962890.1843234452.5517779694

181.539999962337.251770.16859221462.8890297394

191.659999967366.43539430.15618737043.2554651337

201.779999971396.07440191.30E-013.6515395356

211.899999976425.94519049.60E-024.077484726

222.0199999816.57E-02456.30020144.19E-024.5337849274

232.1399998668.60E-02488.54113771.32E-025.0223260651

242.2599997527.89E-02518.81085218.13E-035.5411369172

252.3799996380.1058499068549.35333253.37E-036.0904902497

262.4999995230.1398026496580.75628662.13E-036.6712465363

272.6199994090.1484657973610.28088381.85E-037.2815274201

282.7399992940.1449028999634.39593511.62E-037.9159233552

292.859999181.42E-01654.07037351.54E-038.5699937287

302.9799990651.63E-01670.30749511.43E-039.2403012238

313.0999989511.73E-01688.62017821.43E-039.928921402

323.2199988378.68E-02698.93243411.48E-0310.6278538361

333.3399987220.1498335749706.37933351.35E-0311.3342331696

343.4599986081.30E-01712.84570311.09E-0312.0470788727

353.5799984931.05E-01716.77142337.75E-0412.763850296

363.6999983799.79E-02721.58605965.04E-0413.4854363556

373.8199982641.10E-01724.15948495.82E-0414.2095958405

383.939998151.14E-01724.11706543.68E-0414.9337129059

394.0599980359.93E-02728.0469362.43E-0415.6617598419

404.1799979218.79E-02732.40484622.27E-0416.3941646881

414.2999978077.67E-02750.4878546.07E-0517.1446525421

424.4199976927.48E-02771.71270752.60E-0517.9163652496

434.5399975781.03E-01796.84442149.13E-0618.713209671

444.6599974638.52E-02820.9878543.63E-0619.534197525

454.7799973497.02E-02852.42260743.94E-0720.3866201324

464.8999972343.97E-02881.84985357.46E-0821.2684699859

475.019997124.66E-02905.04577643.20E-0822.1735157623

485.139997005931.56329351.93E-0823.1050790558

495.259996891961.35986331.77E-0824.0664389191

505.379996777996.47088621.63E-0825.0629098053

2006072214b

CALIPSO

MODEL

Aerosol Extinction (1/km)

Hight (km)

-14.6E 23.5N, 2006072214

2006072314a

TIME20060723

LON/LAT-22.81062317

1-0.546.952594761.53E-02

2-0.379999995253.431625371.54E-020.1003842201

3-0.259999990560.747241971.55E-020.1611314621

4-0.139999985768.992126461.55E-020.2301235886

5-2.00E-029.52E-0278.261619571.55E-020.3083852081

60.10000000890.151624724388.657981871.56E-020.39704319

70.21999999880.1598718166100.28623961.56E-020.4973294296

80.34000000360.1612866372113.30641941.58E-020.610635849

90.46000000832.40E-02127.81876371.64E-020.7384546127

100.5799999833143.82632451.70E-020.8822809372

110.6999999881161.58352661.68E-021.0438644638

120.8199999928181.16241461.65E-021.2250268784

130.9399999976202.68673711.82E-021.4277136155

141.059999943226.27883912.91E-021.6539924546

151.179999948251.86317445.42E-021.905855629

161.299999952279.13323978.32E-022.1849888687

171.419999957307.53359990.10915923122.4925224686

181.539999962337.15197750.13478143512.8296744461

191.659999967367.82238770.12866652013.1974968338

201.779999971399.33694469.36E-023.5968337784

211.899999976431.10409556.23E-024.0279378739

222.0199999818.21E-03462.94314583.81E-024.4908810197

232.1399998664.98E-02494.65121461.72E-024.9855322343

242.2599997524.26E-02526.84912116.74E-035.5123813554

252.3799996380.1011383012559.83776865.28E-036.072219124

262.4999995230.1472731829593.1701054.53E-036.665389229

272.6199994090.1339015812619.76965332.19E-037.2851588823

282.7399992940.1176950186643.42974852.08E-037.9285886308

292.859999180.1212706193665.30816652.54E-038.5938967973

302.9799990650.1371465474683.0625613.35E-039.2769593583

313.0999989514.73E-02698.24456794.00E-039.9752039262

323.2199988370.1292796731709.25964364.68E-0310.6844635698

333.3399987220.1054983065717.52966316.14E-0311.4019932329

343.4599986088.69E-02722.01025395.75E-0312.1240034868

353.5799984937.52E-02724.2083743.75E-0312.8482118608

363.6999983798.39E-02725.92315672.68E-0313.5741350175

373.8199982645.46E-02726.66558841.32E-0314.3008006059

383.939998155.65E-02727.80169683.02E-0415.0286023027

394.0599980354.60E-02731.82781981.83E-0415.7604301225

404.1799979214.76E-02732.46789551.01E-0416.492898018

414.2999978073.55E-02752.17309575.42E-0517.2450711137

424.4199976923.56E-02769.29852292.51E-0518.0143696366

434.5399975784.59E-02798.28704831.18E-0518.8126566849

444.6599974632.01E-02834.59613041.48E-0619.6472528153

454.7799973493.19E-02866.1632082.88E-0720.5134160233

464.8999972342.92E-02871.8923952.32E-0721.3853084183

475.019997123.19E-02894.533029.45E-0822.2798414383

485.1399970051.34E-02925.54425051.60E-0823.2053856888

495.259996891959.69085693.47E-0924.1650765457

505.379996777995.4027713.91E-0925.1604793167

2006072314a

CALIPSO

MODEL

Aerosol Extinction (1/km)

Hight (km)

-22.8E 12.1N, 2006072314

2006072314b

TIME20060723

LON/LAT-23.2871513414.27466583

1-0.546.733661655.79E-02

2-0.379999995253.18145375.83E-020.0999151154

3-0.259999990560.463020325.83E-020.1603781357

4-0.139999985768.670852665.83E-020.2290489883

5-2.00E-0277.903884895.83E-020.3069528732

60.100000008988.269950875.86E-020.3952228241

70.219999998899.871215825.97E-020.4950940399

80.3400000036112.90171056.34E-020.6079957504

90.4600000083127.66490946.89E-020.7356606598

100.5799999833144.04856877.72E-020.8797092285

110.6999999881162.06999218.98E-021.0417792206

120.8199999928181.9188081.06E-011.2236980286

130.9399999976203.75071721.22E-011.4274487458

141.059999943227.65919491.31E-011.6551079407

151.179999948253.52883911.30E-011.9086367798

161.299999952281.24288941.24E-012.1898796692

171.419999957310.11041260.12264550482.4999900818

181.539999962339.98651120.12096203862.839976593

191.659999967370.52206420.10951463883.2104986572

201.779999971401.2143869.20E-023.6117130432

211.8999999760.1371763498431.58523566.49E-024.0432982788

222.0199999811.64E-01462.36059573.88E-024.5056588745

232.1399998661.96E-01494.00183111.50E-024.9996607056

242.2599997521.14E-01526.78485113.04E-035.5264455567

252.3799996389.19E-02559.29919432.44E-036.085744751

262.4999995230.2079082727594.55438232.29E-036.6802991333

272.6199994090.1910316497620.63818362.06E-037.3009373169

282.7399992940.1930202246643.46569822.49E-037.9444030151

292.859999180.1870443225665.30853272.78E-038.6097115478

302.9799990650.1047546044682.08227542.46E-039.2917938232

313.0999989518.26E-02696.9132691.98E-039.9887070922

323.2199988376.04E-02708.68206791.86E-0310.6973891601

333.3399987228.74E-02718.28558351.82E-0311.4156747436

343.4599986085.37E-02723.7291261.99E-0312.1394038696

353.5799984936.49E-02727.34338381.88E-0312.8667472534

363.6999983797.13E-02727.49865722.30E-0313.5942459106

373.8199982641.48E-01729.35388181.91E-0314.3235997924

383.939998151.06E-01728.16381841.50E-0315.0517636108

394.0599980354.92E-02730.84985356.17E-0415.7826134643

404.1799979216.09E-02734.73852549.05E-0516.5173519897

414.2999978074.86E-02751.23028563.90E-0517.2685822753

424.4199976925.61E-02774.66192632.36E-0518.0432442016

434.5399975787.54E-02800.84344489.75E-0618.8440876464

444.6599974637.40E-02823.24908452.18E-0619.6673367309

454.7799973497.47E-02852.3020024.04E-0720.5196387329

464.899997234874.1129151.06E-0721.3937516479

475.01999712896.50659183.15E-0822.2902582397

485.139997005930.24554441.05E-0823.2205037841

495.259996891962.9132697.79E-0924.1834170531

505.379996777989.9600834.55E-0925.1733771361

515.4999966621033.2546393.54E-09

525.6199965481073.7885744.25E-09

535.7399964331130.2646487.24E-09

545.8599963191190.8212894.42E-09

555.9799962041269.3356931.82E-09

566.099996091345.6577152.04E-09

576.2199959751437.7524412.50E-09

586.3399958611574.9680181.32E-09

596.4599957471789.6629647.23E-10

606.5799956322128.4177251.20E-09

616.6999955182709.9943854.97E-09

626.8199954033669.2294922.11E-08

636.9399952895778.4130863.78E-08

647.05999517429592.15821.76E-09

2006072314b

CALIPSO

MODEL

Aerosol Extinction (1/km)

Hight (km)

-23.3E 14.2N, 2006072314

Sheet2

Sheet3

Interim summary of NAQFS Experimental PM2.5Winter high bias and summer low bias in PM2.5 mass & regional differences not well understoodNH3 emission issues?NOy budget including dry & aqueous depositions?PM speciation information neededBetter understanding of dependence of PM speciation to gas-phase mechanism necessary gas, aerosol, heterogeneous reaction interactionsDevelop methods (data/algorithms) for including intermittent emissions from forest fire, wind-driven dust, (volcanic ashes, etc & BCs)Link with global models

**********Transition from model underprediction to overprediction observed in CONUS wide averages more-or-less reflected in all regional averages, although timing of transition is not identical.*On Aug 16, 2009, model underprediction is prevalent in the eastern U. S.*Character of model vs observation comparisons has changed dramatically by Aug 24. Analysis to focus on comparison of speciated PM2.5 model predictions vs observations to hopefully provide insight on causes of models seasonal PM2.5 biases.*Change in PM2.5 composition occurred after apparent rain and frontal passage. (Rain sensor at JST was not working during this period)*Character of PM2.5 composition also changed after precipitation and frontal passage. Model results to be compared to SEARCH data and eventually IMPROVE speciated data when it is available.*******Highlights:Dust is emitted from both anthropogenic and natural sources;EPA NEI includes six anthropogenic sources, such as fugitive dust from paved and unpaved road, mining, construction etc.The natural dust emissions, such as wind-blown dust from desert land and cropland, are not accounted for. Because natural dust could have a dramatic effect on air quality, esp. in the Southwest and over the agricultural area, we want to have the forecasting capability of predicting natural dust.The natural dust emission is calculated using the Owens flux equation, and threshold friction velocities from field and wind tunnel studies, mostly by Dale Gillette and colleagues. The land use and soil type data is from USGS, and soil moisture is obtained from real-time weather forecast model;We also simulate crop and vegetation growth over the US based on planting and harvesting information provided by USDA national agricultural statistical service (NASS);*Highlights:The addition of natural dust emissions improves CMAQ performance over the dust active area. Here are two examples of comparing the model with IMPROVE measurements. The green line is CMAQ without natural dust, the red line is CMAQ with dust, and the dash line is IMPROVE observation. At both GUMO and SACR sites, adding the dust emissions has significantly improved the model performance.The missing dust sources over the northern Mexico are responsible for the remaining discrepancy between the model and observation. 46Several NAM upgrades were made in 2006 and 2007 that I think also contributed to the AQF positive performance.

Retrospective experiments were done for all potential configurations followed by real time testing on May 16.Most important change included tight coupling of vertical coordinates and improvements to emissions for california