intercomparisonof chemical multiphase box models

Intercomparison ofChemicalMultiphaseBoxModelsMaryCBarth1,BarbaraErvens2,Hartmut Herrmann3,AndreasTilgner3,VFayeMcNeill4,AnnMarieCarlton5,SaraLance6,MauroMorichetti7,LaurentDeguillaume8,andNadineChaumerliac8

1NationalCenterforAtmosphericResearch,Boulder,CO,UnitedStates,2CooperativeInstituteforResearchinEnvironmentalSciences,Boulder,CO,UnitedStates,3LeibnizInstituteforTroposphericResearch,Leipzig,Germany,4ColumbiaUniversityofNewYork,Palisades,NY,UnitedStates,5UniversityofCaliforniaIrvine,Irvine,CA,UnitedStates,6UniversityatAlbanyStateUniversityofNewYork,ASRC,Albany,NY,UnitedStates,7UniversityofPolytechnicofMarche,Ancona,Italy,8LaboratoiredeMétéorologie Physique(LaMP),Clermont-Ferrand,France

Goal:EvaluateCurrentStateofKnowledgeinMultiphaseChemistryBoxModels

• FivegroupsareconductingsimulationsinthecontextoftheSeptember17-19WhitefaceMountainCloudEvent

• Gas-phasechemistryhassomevariationamongmodelsduringdaytimethatmustbeaccountedforininterpretationofcloudchemistryresults

• Cloudchemistryresultsshowwiderangeofanswers,especiallyfororganicacidformation

• MorevariabilityfoundwithvaryingpHsimulation• Understandingthesedifferencesiscurrentlyunderway

https://www2.acom.ucar.edu/cloud-chemistry

Gaschemistry Aqueouschemistry Gas-liquidtransfer Reference

TROPOS(Tilgner,Herrmann)

MCMv3.213,927reactions

CAPRAM4.0a7129reactions 275species Tilgner etal.(2013,J.

Atmos.Chem.)

Deguillaume MCMv3.3.12043reactions

CLEPS850reactions 591species Mouchel-Vallon etal.

(2017,GMD)

McNeill

Isoprene,aromatics,andC1-C3 photochemistry

165reactions

GAMMA239reactions 35species McNeilletal.(2012,

ES&T)

BarthSimilartoMOZART4

168reactions45reactions 45species Lietal. (2017,JGR)

Ervens SimilartoBarth’s168reactions

Ervens58reactions 22species Ervens etal.(2014,

JGR;2008,GRL)

SampleofBoxModelResults

• Location:WhitefaceMountain:z=1.5kmMSL,44.4N,73.9W

• Start/Endtimes:17:30LT17Sept./15:00LT18Sept.

• 30minutesclearsky,20hourscloud,30minutesclearsky

• Simulation1:ClearSkyOnly

• Simulation2:CloudWater=0.78g/kg,pH=4.5

• Simulation3:CloudWater=0.78g/kg,pHvariesascalculatedbymodel

ModelConfiguration ConclusionsEffectsofCloudsonTroposphericComposition

• Acidrainstudiesfromthe1980sand1990sidentifiedimportanceofaqueous-phasechemistryinproducingsulfate

• Cloudsaffectozoneviaaqueouschemistry,scatteringofradiation,andlightning-NOx production

• Cloudchemistrycanproducemoresecondaryorganicaerosols

www.thelivingmoon.com

• Three-dimensionalchemistrytransportmodelsoftendonotincludeaqueous-phasechemistryduetolackofcompleteunderstandingofthechemistryandthecomputationalburden

• Goal:Evaluatethecurrentstateofknowledgeinmultiphasechemistryboxmodels

Background

• Intercomparison isbeingconductedinthecontextoftheWhitefaceMountainCloudChemistryStudy

• Cloudeventof17-19September2016isbeinganalyzedforitscompositionbyseveralgroups

• Inthisstudywemodelthefirst20hoursofthecloudeventusingmeteorologicalconditionsatWhitefaceMountain

Cloudsassociatedwithwarmfrontandwarmsectorstorms/clouds

SurfaceWeatherMap1230UTC17Sept0830LT

WFM

Cloudswerestratiform innature

• InitialconcentrationsarefromaWRF-Chem simulationof16-19September2016continentalUnitedStates

• PhotolysisratesfromTUVv5.3forWFMinSeptember,forclearskywithsomeaerosols

• CCNcomposedofSO4,NH4,OrganicCarbon

• Clouddropssetto10µmradius

MeteorologyoftheCaseSimulated

AirfromOhioRiverValley

Variationinclear-skyresultsneedstobeaccountedforininterpretingmultiphaseresults

Gas-phaseOxidants

OHhasfactorof2-3variation HO2 hasfactorof~2variation

H2O2 hasfactorof1-2variation

O3 rangesfrom39-44ppbv

• Gas-phaseHCOOHproductionis50-70pptvinthreemodels;itdoesnotoccurintheMOZART4gas-phasemechanism

• CH3COOHproductionis~100pptv forallmechanismsexceptMcNeillwhopredictlargerproductionofCH3COOHingasphase

Gas-phaseOrganicAcids

Simulation1:ClearSkyOnly

ThankstoWilliamGangTsui forhiscontributiontoMcNeill’ssimulations.ThankstoNCAR/ACOMforsupportingcloudchemistrymodelingintercomparison meeting.NCARissupportedbytheNationalScienceFoundation.

Gas-phaseOxidants

OHhasfactorof10variationHO2 hasfactorof~5variation

H2O2 agreeswellexceptforaftercloudevent

O3 rangesfrom35-43ppbv

Variationincloudyresultsisgreaterthanthatfoundinclear-skycase

Gas-phaseOrganicAcids Aqueous-phaseOrganicAcids

Aqueous-phaseOxidants

• Widevarietyofanswersamonggroupsastohowmuchorganicacidsareproduced,althoughmostgroupsagreeonCH3COOHproduction

• Timeseriesoftotalorganicacid(sumofallorganicacids)willprovideinsightofpartitioningamongacidsorsimplydifferentoxidationrates

Simulation2:SetLWC=0.78g/kg,SetpH=4.5

cloud cloud

Variationincreasesduringdaylighthours

cloudcloud

cloud cloud

cloudcloud

cloudcloud

Aqueous-phaseOxidants

Aqueous-phaseOrganicAcids

Modelresultsvaryby1-5ordersofmagnitude

Simulation3:SetLWC=0.78g/kg,pHVaries

pHvaluesrangebetween4and4.8

cloudcloud

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