1、1Designations for the 2006 PM2.5 Standards:Evaluating the Nine Factors in Setting Nonattainment Area Boundaries2 The 9 Designation Factors To Help Determine Nearby Area of Influence for 24-hr NAAQS ViolationsEmissionsAir QualityMeteorologyTopographyPolitical and OtherBoundariesCurrent EmissionContro
2、lsGrowthTraffic&CommutingPopulation andUrbanizationNonAttainment BoundariesAir Quality is one of the most Important Designation Factors3Topics to be Covered Conceptual model for high PM days Seasons when exceedances occur Composition of the high days Analytical tools SLICE technique-for evaluating u
3、rban contributions to high days Residence time analysis for assessing nearby contributing source regions using back trajectories and emissions data Gradient analysis for identifying days with potential high source-oriented impacts4Conceptual Model for High PM2.5 Days How to define high PM2.5 days?Wh
4、at is the typical“daily increment”for high PM days in relation to the annual average?What is the urban contribution above regional levels?5Conceptual Model for High PM2.5 Days What high PM2.5 days to consider?“High PM2.5 Days”Associated with the 98th percentileNot just one day per yearSelect all can
5、didate days e.g.top 5%or days 30-35ug/m3Summarize by season to distinguish varying conditions640ug/m31624PM2.5 High Day ValueSeasonalAverage+Typical Daily IncrementExampleTypical Daily Increment-Example The annual average PM2.5(urban background)is the stuff that is there on a day-to-day basis.Comes
6、from nearby and more distant areasCan be estimated by seasonal average PM2.5 concentration of non-high daysIncludes contributions from all nearby surrounding countiesCan be estimated using the traditional urban increment approach The daily increment(on top of annual average urban background)also has
7、 regional and local contributions.-Key issue:what counties and sources from the urban area contribute to the typical daily increment?Conceptual Model for High PM2.5 Days High Daily PM2.5 has Urban and Regional Components7Conceptual Model for High PM2.5 Days An approach to partition typical levels in
8、to urban and regional componentsUrban Increment Analyses as used in 2004/2005 PM2.5 DesignationsUrban sources in the Eastern US contribute at least 4-6 ug/m3 to annual average PM2.5 Probably even larger urban contribution in western US citiesCarbon is significant component of average PM2.5 mass,but
9、metro area emissions typically are much less than SO2 and NOxWeighted emissions score developed to give additional weight to nearby direct carbon emissions as they contribute to the urban background8urban incrementPM g/mnatural backgroundUrban areas14-20 ug/m3Countryside10-12 ug/m310152030253540Conc
10、eptual Diagram-Annual Average PM2.5 Air Quality-Annual Average PM2.5 regional contributionWestern US urban areas may have smaller regional contribution9urban incrementPM g/mnatural background10152030253540Conceptual Diagram-High Daily PM2.5 Concentrations Air Quality -High Daily PM2.5 Concentrations
11、 regional contributionUrban areas30-40 ug/m3 Countryside18-30 ug/m3 Larger “urban island”on peak daysFocus of new analyses:understanding what emissions contribute to urban incrementWestern US urban areas may have smaller regional contribution10Conceptual Model for High PM2.5 Days Source region consi
12、derationsRole of Regional vs Urban vs Micro-scale InfluencesOn high days particularly in the east,regional emissions often provide a“base”amount of pollutionUrban-wide and nearby emissions also contribute significantly to high days:“urban island”effectIn some cases,there may be a micro-scale effect
13、from a single source or small group of sourcesDoes not help define NA boundaries,unless it is the only contributing source(Note:“urban”can mean large metropolitan area or smaller city)Air Quality11Conceptual Model for High PM2.5 Days Seasons when exceedances occurTime of Year for Exceedances-varies
14、by Geographic RegionSE:Mostly summerIndustrial Midwest(IMW),Mid-Atlantic,So.CA:Winter and summer NW,UT,NM,Middle CA:Mostly or exclusively Winter12Percent of 2003-05 Days 35 ug/m3,by Month (NW)Based on all FRM Site-days throughout the Regional DomainPLOTGT 35 ug/m3 at FRM sitesPvX 0 10 20 30 40 50JFM
15、AMJJASOND%50 250Percent of 2003-05 Days 35 ug/m3,by Month (IMW)Based on all FRM Site-days throughout the Regional DomainPLOTGT 35 ug/m3 at FRM sitesPvX 0 10 20 30 40 50JFMAMJJASONDPercent of 2003-05 Days 35 ug/m3,by Month (N.Eng-MidAtl)Based on all FRM Site-days throughout the Regional DomainPLOTGT
16、35 ug/m3 at FRM sitesPvX 0 10 20 30 40 50JFMAMJJASONDPercent of 2003-05 Days 35 ug/m3,by Month (SE)Based on all FRM Site-days throughout the Regional DomainPLOTGT 35 ug/m3 at FRM sitesPvX 0 10 20 30 40 50JFMAMJJASONDPercent of 2003-05 Days 35 ug/m3,by Month (UT)Based on all FRM Site-days throughout
17、the Regional DomainPLOTGT 35 ug/m3 at FRM sitesPvX 0 10 20 30 40 50JFMAMJJASONDPercent of 2003-05 Days 35 ug/m3,by Month (Mid.Cal)Based on all FRM Site-days throughout the Regional DomainPLOTGT 35 ug/m3 at FRM sitesPvX 0 10 20 30 40 50 60JFMAMJJASONDPercent of 2003-05 Days 35 ug/m3,by Month (S.Cal)B
18、ased on all FRM Site-days throughout the Regional DomainPLOTGT 35 ug/m3 at FRM sitesPvX 0 10 20 30 40 50JFMAMJJASONDNWUTIMWMid CAS.CASEMidAtlPercent of 2003-05 FRM Days 35 ug/m3 by Month Based on all sites which violate 24-hr NAAQSJ F M A M J J A S O N D J F M A M J J A S O N DJ F M A M J J A S O N
19、DLa Cruces,NMPercent of 2003-05 Days 35 ug/m3,by Month (Las Cruces)Based on all FRM Site-days throughout the Regional DomainPLOTGT 35 ug/m3 at FRM sitesPvX 0 10 20 30 40 50JFMAMJJASOND%50 250J F M A M J J A S O N D 13Conceptual Model for High PM2.5 Days Composition data are important1)CompositionInd
20、icate which sources are contributing to average and high PM2.5 valuesVaries across country Warm season exceedances:Mostly sulfate+organic carbonCold season exceedances:Nitrate(at higher latitudes and in Western US)+sulfate+carbon;Carbon may dominate in some locations(e.g.MT,ID)Gaps in speciation dat
21、a for certain areasAir Quality14Composition on Annual Average and High PM2.5 Days(From PM Staff Paper)Some source categories and regional influences may be more important for high concentration daysComparing average of 5 highest days during 2003,regional sources of sulfates and nitrates are larger c
22、ontributors to peak day concentrations than to annual average(selected city analysis)Composition can vary from high day to high dayCarbon can be smaller as%-but still larger in absolute concentration values-compared to the averageNote:All the new analyses present“FRM”composition with the peer-review
23、ed“SANDWICH”TechniqueAs used in CAIR and PM2.5 RIASMWCANEFrom PM Staff Paper(Rao et al)BirmAtlantaNYCClevelandChicagoSt.LouisSLCFresnoUTMore Sulfate More Nitrate High PM2.5 days have:NitrateTCMSulfateCrustal This analysis showsPM2.5 Composition of the ambient aerosol(not adjusted to represent FRM ma
24、ss)Air Quality15Percent of 2003-05 Days 35 ug/m3,by Month (Las Cruces)Based on all FRM Site-days throughout the Regional DomainPLOTGT 35 ug/m3 at FRM sitesPvX 0 10 20 30 40 50JFMAMJJASONDPercent of 2003-05 Days 35 ug/m3,by Month (IMW)Based on all FRM Site-days throughout the Regional DomainPLOTGT 35
25、 ug/m3 at FRM sitesPvX 0 10 20 30 40 50JFMAMJJASONDPercent of 2003-05 Days 35 ug/m3,by Month (N.Eng-MidAtl)Based on all FRM Site-days throughout the Regional DomainPLOTGT 35 ug/m3 at FRM sitesPvX 0 10 20 30 40 50JFMAMJJASONDPercent of 2003-05 Days 35 ug/m3,by Month (SE)Based on all FRM Site-days thr
26、oughout the Regional DomainPLOTGT 35 ug/m3 at FRM sitesPvX 0 10 20 30 40 50JFMAMJJASONDPercent of 2003-05 Days 35 ug/m3,by Month (NW)Based on all FRM Site-days throughout the Regional DomainPLOTGT 35 ug/m3 at FRM sitesPvX 0 10 20 30 40 50JFMAMJJASONDPercent of 2003-05 Days 35 ug/m3,by Month (UT)Base
27、d on all FRM Site-days throughout the Regional DomainPLOTGT 35 ug/m3 at FRM sitesPvX 0 10 20 30 40 50JFMAMJJASONDPercent of 2003-05 Days 35 ug/m3,by Month (Mid.Cal)Based on all FRM Site-days throughout the Regional DomainPLOTGT 35 ug/m3 at FRM sitesPvX 0 10 20 30 40 50 60JFMAMJJASONDPercent of 2003-
28、05 Days 35 ug/m3,by Month (S.Cal)Based on all FRM Site-days throughout the Regional DomainPLOTGT 35 ug/m3 at FRM sitesPvX 0 10 20 30 40 50JFMAMJJASONDNWUTIMWMid CAS.CALa CrucesNMSEMidAtl Avg High 3 Cold Avg High 3 Warm Avg High 3 Cold Avg High 3 Warm Avg High 3 Cold Avg High 3 Warm Avg High 3 Cold“E
29、xample”Composition for High Days“Warm”Season(May-Sept)&“Cold”But sites can be different within each“domain”ColdCold WarmCold WarmWarmCold WarmColdColdColdEl Paso STNor J F M A M J J A S O N DJ F M A M J J A S O N D%50 250%50 250Pies represent average of 3 highest days per year per season,using SANDW
30、ICHor16IMW-551330027 Wisconsin Milwaukee-Waukesha,WI 24-hr DV=36 ug/m3 Annual DV=13.5 ug/m3Total 3 yr obs=161 cold days 30=5 warm days 30=1 Avg conc.-top 3 values/yr:39.0 ug/m3 41.1 ug/m3 Sulfate_massNitrate_massECOCMmbCrustalPassive AVG Avg High 3 Cold Avg High 3 WarmComposition is often similar am
31、ong the high days3 highest PM2.5 days 30ug/m3Per season,Milwaukee,WI (2003-05)Average Cool Season Warm SeasonMeasuredPM2.5 mass,ug/m3Black line is difference between OCMmb and OCM14Milwaukee,2003-05S.CAGray line shows OCMmb-OCM14ChemSulfate_massNitrate_massECOCMmbCrustalPassivePM2.5 and component ma
32、ss,ug/m3-20.02.04.06.08.0 10 12 14 16 18 20 22 2420022003200420052006PM2.5 days 30ug/m317Use resident time weighted emissionsto partition each component of total dailyIncrements into urban®ional contributions(%of RTWE in local area)Conceptual Model for High PM2.5 Days An approach to partition tot
33、al daily increment into urban and regional componentsIMW 550790026 Tot warm days=142 Wisconsin Milwaukee-Waukesha,WI High days=324-hr DV=.ug/m3 Annual DV=.ug/m3 Values under other bars are the daily concentration.-Estimated INCREMENT COMPOSITION is shown First bars are seasonal and annual averages(l
34、atter if data is complete)ChemSulfate_massNitrate_massECOCMmbCrustalPassivePM2.5 and component mass,ug/m30.05.0 10 15 20 25 30 35 40 45 50 55 60 6511.89912.42034.84245.60746.664SASASASASASAIMW 550790026 Tot cold days=183 Wisconsin Milwaukee-Waukesha,WI High days=824-hr DV=.ug/m3 Annual DV=.ug/m3 Val
35、ues under other bars are the daily concentration.-Estimated INCREMENT COMPOSITION is shown First bars are seasonal and annual averages(latter if data is complete)ChemSulfate_massNitrate_massECOCMmbCrustalPassivePM2.5 and component mass,ug/m30.05.0 10 15 20 25 30 35 40 45 50 55 60 6512.43612.64632.34
36、432.70533.96435.04335.74440.05741.02041.538ASASASASASASDaily compositionminus Seasonal avg.PM2.5 days 30ug/m3Per season&year,Milwaukee,WI (2003-05)MeasuredPM2.5 massThe urban background PM2.5 can be estimated using seasonal average PM2.5 concentration of non-high daysCool WarmCoolseasonWarmseasonNex
37、t subtract the daily composition from the seasonal average PM2.518Analytical Toolsto help identify boundaries and develop SIPs SLICE technique-for evaluating urban contributions to high days Residence time analysis for assessing nearby contributing source regions using back trajectories and emission
38、s data Urban gradient analysis for identifying whether there are any sites predominantly affected by a single source19“SLICE”to identify“urban island”days and relative urban amount of PM2.5 massEvidence of urban source contributions Urban“gradient”technique Evidence of predominant strong nearby sour
39、ce influenceAnalytical ToolsIdentify urban PM2.5 and gradients Air QualityAir QualityEmissionsMetDaily urban portion of PM2.520Analytical Tools-Residence Time Analysis Where did the air parcel come from on high concentration days?1)Transport patterns producing a potential source regionUse trajectori
40、es and“Residence-Time Analysis”to find upwind probability fields.For PM2.5 mass or its componentsFocus on the ensemble of“High PM2.5 days”,by season for subsequent linking to composition pattern.Days with identified“urban islands”are more importantLocal pollution roses(annual vs.high days)would also
41、 be helpful to identify nearby sources.MetAir QualityResidence time probability plots with HYSPLIT trajectories have been used by Kinski,Poirot and others to identify potential source regions.21Analytical Tools-Residence time weighted emissionsWhat are the most likely contributing emissions?1)Spatia
42、l distribution of emissions by season Developed from monthly emissions for precursors and direct PM:(SO2,NOx,Carbon,Crustal)The importance of each precursor pollutant can be guided by the composition of the high PM2.5 day.consider monthly emissions corresponding to the affected PM component accordin
43、g to typical composition by season.Some precursors will not be considered or could be down-weighted.e.g.crustal(year-round)and NOX(summer).Residence time weighted emissionsUse probability that air parcel passed over an area to weight emissions as potential contributors to the high day concentration
44、impactsHigh probability nearby contributing emissions can be identified for each PM2.5 contributorEmissionsMetEmissionsAir Quality22Summary Identifying the area of emission influence considers contributions for each“high PM2.5 day”and urban average background on top of which are the daily impacts Hi
45、gh concentration days with evidence of urban influence(i.e.with urban islands)are more important The magnitude of urban island can help define the daily urban contributions.In combination with daily and average speciation data,by season of the year Emissions with high probability of trajectory residence time are important to assess high day impacts.Average emissions and typical wind patterns help understand the sources contributing to the urban“background”Both used to understand the relative importance of the various nearby contributing emissions(e.g.direct PM vs SO2 vs NOx).
