Update on IMPROVE Light ExtinctionEquation and Natural Conditions EstimatesTom Moore, WRAP Technical CoordinatorMay 23, 2006OR .......Defining Regional Haze Impacts withAerosol Sampling DataAND .......Knowing the unknowable“Old” IMPROVE Light Extinction Equation•Developed in late 1980’s –consensus light extinctioncoefficients for species measured by IMPROVE aerosolsampler•Adopted by EPA for “Tracking Progress” –regional hazemonitoring guidance documents are at:http://vista.cira.colostate.edu/improve/Publications/GuidanceDocs/guidancedocs.htm•Equation is used to estimate light scattering by particles:[][ ][ ][ ][ ][ ]106.01104)(3)(3+×+×+×+×+××+××≈MassCoarseSoilFineCarbonElementalMassOrganicNitrateRHfSulfateRHfbext“Revised” IMPROVE Light Extinction Equation•Review process by IMPROVE Steering Committee andscientific community during 2005•Findings of review prepared by Jenny Hand & Bill Malmpresented and discussed at:http://www.wrapair.org/forums/aamrf/meetings/050608den/index.html•Technical document describing revised equation:http://vista.cira.colostate.edu/improve/Publications/GrayLit/019_RevisedIMPROVEeq/RevisedIMPROVEAlgorithm3.doc•Light extinction data from 2000 onward are calculated andavailable using old and revised equation on VIEWS:http://vista.cira.colostate.edu/views/and the WRAP TSS:http://vista.cira.colostate.edu/tss/“Revised” IMPROVE Light Extinction Equation[][][ ][][ ][][ ][ ][ ][ ][ ]ppb)(NO0.33Specific)iteS(ScatteringRayleighSaltSeaRH)(f1.7MassOrganicargeL6.1MassOrganicSmall2.8NitrateargeLRH)(f5.1NitrateSmallRH)(f2.4SulfateargeLRH)(f4.8SulfateSmallRH)(f2.22SSLSLS×++×+××+×+×+×+×+××+××+××+××≈MassCoarseSoilFineCarbonElementalbext6.0110Bottom line:•New equation fitted to aerosol data collected 2000-04 usinglight extinction coefficients from research literature, tobetter match observed optical light scattering data•Corrects bias but increases scatter at some sitesLight Extinction using old and revised IMPROVE Equation050100150200250300350050100150200250300350MeasuredBsp

IM P R O V E B s pScatter plot of the old IMPROVE equation estimatedparticle light scattering versus measured particle lightscattering.050100150200250300350050100150200250300350MeasuredBsp

S p li t C o m p o n e n t M e th o d B s pScatter plot of the revisedIMPROVE equation estimatedparticle light scattering versus measured particle lightscattering.ScatterPlotforGRCAusing IMPROVEAlgorithm11010010001101001000MeasuredBsp

Pr e d i c t e d BspScatterPlotforGRCAusingNewAlgorithm11010010001101001000MeasuredBsp

Pr e d i c t e d Bs pNatural Conditions Estimates•NAPAP Visibility Report (Volume 24) [1990] authored by Trijonis,et. al.•Based on available IMPROVE network data and other data sources•Estimated contiguous East and WestU.S. annual average natural massloading for visibility-impairing aerosols [specified uncertainty by species]•[Well] Known to underestimate natural carbon•Adopted by EPA for “Estimating Natural Visibility Conditions” using“old” equation –regional haze monitoring guidance documents are at:http://vista.cira.colostate.edu/improve/Publications/GuidanceDocs/guidancedocs.htm•Default Natural Haze Levels Sensitivity Assessment projectfor the 5RPOs•Ivar Tombach is doing the analysis•Initial findings werepresented at a June 2005 workshophttp://www.wrapair.org/forums/aamrf/meetings/050608den/index.html•Final report soon?“Default” Natural Conditions Estimates20% Best Days (left) & 20% Worst Days (right)What should be done [if anything] with “default”Natural Conditions Estimates?•Knowing the unknowable –April 4, 2006–Inter-RPO Monitoring andData Discussion Group analysispresentationon revised natural conditionestimates using the new IMPROVE algorithmand a revised statisticalapproach –Ames & Pitchford•Things to think about:–Natural conditions vary continuously in space andtime –do any historic data informbetter estimates for planning purposes?–Theworst andbest visibility days’ default natural conditions estimates areprojectedfrom measured distributions ofaerosol data –these are for total light extinction inDECIVIEWS,not for individual species –howdoes that line up for the WRAP region?–How often willwe see frequent large OC/ECandDust events over the next 50 to 60years?–Doweneed to apply the revised IMPROVEequation to naturalconditionsestimates?–What monitoring period of record canbeused to estimate naturalconditions?–Can we make a better estimate of the distributions of worst and best visibility days 58years out, than John Trijonis did?–What are the planning implications of adjusting natural conditions estimates up and/ordown and changingthe glide pathfor 116 Class I areasin the WRAPregion,either for deciviews or individual species?–Where does take us for “demonstrating” reasonable progressin 2018?–Morequestionsyettoasked -Next Steps on Natural Conditions Estimates inthe WRAP Region•Attribution of Haze workgroup conference callJune 7thto review monitoring data issues:http://www.wrapair.org/cal/calendar.php?op=view&id=552•Plan to have AoH workgroup recommendWRAP region approachhttp://vista.cira.colostate.edu/tss/