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, Climate 4 Sciences Sciences , Dynamics 3 of the Past Solid Earth , Techniques Geoscientific Methods and 2 and Physics Atmospheric Atmospheric Atmospheric Data Systems Geoscientific Earth System Earth System Measurement Instrumentation Hydrology and Ocean Science Annales Annales Biogeosciences The Cryosphere Natural Hazards Hazards Natural cient to be measured; (D) and Earth System System Earth and ffi Model Development Geophysicae 0.5) is characteristic of freshly , M. Kulmala 4 ∼ , J. N. Smith 1 erences in the overall growth rate from ff , T. Petäjä * , Open Access Open Access Open Access Open Access Open Access Open Access 2 Open Access Open Access Open Access Open Access Open Access Open Access Open Access

14116 14115 1 , J. W. DePalma 1 Climate Sciences Sciences Dynamics Chemistry of the Past Solid Earth Techniques Geoscientific Methods and and Physics Advances in Advances Atmospheric Atmospheric Atmospheric Data Systems Geoscientific Geosciences Earth System Earth System Measurement Instrumentation Hydrology and Ocean Science Biogeosciences The Cryosphere Natural Hazards Hazards Natural EGU Journal Logos (RGB) EGU Journal and Earth System System Earth and Model Development , L. Hildebrandt Ruiz , B. R. Bzdek 3 1 , and M. V. Johnston 4 This discussion paper is/has beenand under Physics review (ACP). for Please the refer journal to Atmospheric the Chemistry corresponding final paper in ACP if available. Department of Chemistry and Biochemistry,Atmospheric University Chemistry of Division, Delaware, Newark, National DE Center 19716, for USA Atmospheric Research, 1850Department Table of Applied Physics, UniversityDepartment of of Eastern Physical Finland, Sciences, Kuopio, University 70211, of Finland Helsinki, 00014, Helsinki, Finland now at: Department of Chemical Engineering, University of Texas at Austin, Austin, TX Atmospheric new particle formationnucleate (NPF), to the form clusters process on whereby the gaseous order of precursors one nanometer and then grow rapidly to larger ists for ammonia uptake;particle (F) mass carbonaceous growth matter and accountsformed its for secondary oxygen-to-carbon more organic ratio than aerosol; ( half andone of formation (G) event the di to another arechemical caused species, by not variations just in one the individual growth species. rates of all major 1 Introduction furic acid condensation substantiallynanoparticles impacts before the new chemical particles composition haveammonium grown of and to preexisting a sulfate size su uptake are is highly driven correlated, by indicating sulfuricnot that reach acid ammonia the uptake; predicted (E) thermodynamic sulfate endpoint, neutralization suggesting by ammonium that a does kinetic barrier ex- must exceed the lossCCN rate size range. due In toter this scavenging particles work, during in chemical NPF orderand composition in for quantitative Hyytiälä, measurements assessment the Finland, of of in particles 20 important March–April(A) nm to growth 2011 sulfuric diame- channels. reach permit acid, In identification the a thisless work key than we species half show of associated that: particle witha mass growing atmospheric growth particle nucleation, during during this NPF accounts timesulfuric is for quantitatively period; acid explained (B) , by the condensation in sulfate of other content gas words of phase sulfuric acid uptake is collision limited; (C) sul- Atmospheric new particle formationcles (NPF) that is may a contributenuclei key substantially (CCN). source to While of NPF the is ambientcentration global driven depends ultrafine production by strongly parti- of atmospheric on atmospheric nucleation, cloud growth its condensation mechanisms impact since on the CCN growth con- rate Abstract Identification and quantification of particle growth channels during new particle formation M. R. Pennington Atmos. Chem. Phys. Discuss., 13, 14115–14140,www.atmos-chem-phys-discuss.net/13/14115/2013/ 2013 doi:10.5194/acpd-13-14115-2013 © Author(s) 2013. CC Attribution 3.0 License. A.-M. Kortelainen D. R. Worsnop 1 2 Mesa Dr., Boulder,3 CO 80305, USA 4 * 78712, USA Received: 5 March 2013 – Accepted: 13Correspondence May to: 2013 M. – V. Published: Johnston 30 ([email protected]) May 2013 Published by Copernicus Publications on behalf of the European Geosciences Union. 5 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ort has been devoted ff ects (Gong et al., 2008; ff cient to explain nucleation (Kirkby ffi 14118 14117 However, the extent to which other chemical species contribute to growth is not While much progress has been made in understanding the mechanisms underlying Atmospheric NPF is a two-step process involving (1) the nucleation of small particles the Nano Aerosol Massthat provides Spectrometer a quantitative (NAMS), measure a of(Wang particle and single composition Johnston, in particle 2006; the Wang 10–30 mass nm ettermine size spectrometer al., quantitatively range 2006; the Pennington and contributionsduring Johnston, of 2012) NPF certain to in de- chemical the speciesthe remote to contributions boreal particle of forest various growth environment.to chemical accurately A species assess quantitative to the understanding particle impact of of growth NPF is on necessary CCN in levels and order climate. et al., 2010a,b) and byraud organic et matter al., (Donahue 2012). et al., 2011; Monge etknown, al., in 2012; part Per- because few instrumentsmeasurements in can provide the quantitative nanoparticle chemical size composition regime (Bzdek et al., 2012a). This work utilizes (Riipinen et al., 2007;rates based Kuang on et gas phase al.,growth sulfuric 2010). rates acid It concentrations during usually has ambient doto been not NPF, growth suggesting match shown (Kuang measured that that et othercal expected al., composition chemical growth 2010; measurements species in Smith contribute of the et molecular 10–30 al., nm species size 2008; including2005, range sulfate, Stolzenburg 2008, have nitrate, 2010). et implicated Several ammonium potential al., a and growthconcerning 2005). channels variety organics have growth Chemi- been (Smith by suggested, et especially aminium al., salts (Barsanti et al., 2009; Smith et al., 2010; Wang et al., 2009). nucleation, the chemical mechanisms governinginen particle et growth al., are 2012). less Forgrow a certain at nucleated (Riip- nanoparticle a to rate become that climatically is relevant, it much must higher than the rate at which it is lost due to scavenging on the sulfuric acid (Kuang et al., 2008; Metzger et al., 2010; Nieminen mainly by the formation ofand uncharged clusters involves in sulfuric the acid atmospherewater, (Sipila (Kulmala ammonia et et (Ball al., al., et 2007) 2010; al.,(Berndt Young 1999; et Benson et al., et al., al., 2008; 2010; 2009;densable Weber Korhonen et species Yu et al., et (Metzger al., 1997), al., 1999), etHou amines al., 2012; et 2010) Zollner al., such et 2013).nucleation, as al., Indeed, as organic 2012) organic sulfuric acids species and acid (Zhanget such and possibly et ammonia al., as organic al., are 2011). amines con- 2004b; insu are Nonetheless,as likely sulfuric the involved acid nucleation during appears rate in to both be laboratory the and key field chemical measurements component, frequently depends Kulmala et al., 2004). or clusters at a criticalsizes size (Kulmala and et (2) spontaneous al., growthto 2000, of understanding 2013; the the Zhang critical et atmospheric nucleus to al., nucleation larger 2012). process. Much Nucleation e is thought to occur (Oberdörster et al., 2005).ciated Exposure with to higher elevated nanoparticle incidencesKnibbs of concentrations et is adverse asso- cardiopulmonary al., e arising 2011; from Maudgalya secondary et sources canconcentration al., account (Klems et 2008). for al., over In 2011). 50 % Into urban fact, of enhance anthropogenic the environments, pollution the nanoparticle has nanoparticles been formation number 2009). suggested of Despite nanoparticles the importance overact forested of mechanisms environments nanoparticles governing (Zhang to NPF et climate are and al., human poorly health, understood the (Bzdek ex- and Johnston, 2010; 2005; Kuang et al.,patterns 2010; (Lee and Merikanto Feingold, et 2010)ing al., and climate cloud 2009) (Rosenfeld albedo and et al., (Charlson therebyto 2008) et influence human through health, al., precipitation chang- NPF 1992; producessmall Lohmann a size large and they number Feichter, can of 2005). nanoparticles deposit With and throughout respect because the of respiratory their tract or enter the bloodstream sizes, can significantly impact cloud condensation nuclei (CCN) levels (Kerminen et al., 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | (1) and 4 + ;S 4 + , focused to 1 − and O 1 charge and then 3 + + ered by less than 10 % ff ; size measurement with di m d m d 400 V and Einzel lens voltage − and mn d . Since carbonaceous matter is the major 3 − 14120 14119 , is 1 gcm 0 ρ 3 nm particles (DIT ring electrode frequency of 10 kHz and 4 m through a 1.27 cm (O.D.) length of copper tubing at a flow ± 10 % of the true values (Zordan et al., 2010). Mass fractions ∼ 507 V). Other relevant parameters are DIG frequency of 50 kHz ± − 500 V, field adjusting lens voltage of ± 3 . / 1 1 504 V/ −  (Kuwata et al., 2011) meaning that + 0 3 ρ ρ −  100 µm). The laser pulse forms a plasma that completely disintegrates the 4O for sulfate) and converting from elemental to elemental mass m < + erential mobility particle sizer, DMPS) is described by d ff larger). ), defined as the diameter of a spherical particle having unit density and the same = 50 V (Pennington and Johnston, 2012). The relationship between mass normalized ) was accomplished by the method of Zordan et al. (2010). After deconvolution, the 2 − Particle mass spectra consisted of a series of multiply charged atomic ions. Raw Particle size selection in NAMS is accomplished by selective trapping inside the DIT NAMS has been described in detail elsewhere (Wang et al., 2006; Wang and John- mn mn + mn d d (e.g. S fraction. If fewer than 20 particlestime were blocks analyzed, until then aerages averaging minimum was simultaneously of performed minimizes 20 over particles random multiple while maximizing was error time-resolution achieved. from (Klems Performing and non-uniform 20-particletime Johnston, blocks plasma 2013). av- was Averaging energetics needed over only multiple duringwhich periods generally of occurred very at lowwith night. particle number In NAMS concentration, general, to elemental within of mole molecular fractions species are measured are determined by combining the appropriate number of determination. Deconvolution of overlappingO signal intensities (C signal intensities for each element werethe summed mole and fraction the of relative each valuesparticles element were analyzed in taken in the as a particle. 10 Mole min fractions time were block averaged corresponding over to all the DMPS scanning period. component of particles in Hyytiälä,of the 1.3 gcm ambient particle density( was likely on the order spectra were baselinevant corrected atomic and ions the formole signal carbon fractions intensities of (C), integrated each nitrogennot element over (N), quantitatively in the measure oxygen the the rele- (O) particle and are content, sulfur determined. so it (S) Note is that so not NAMS that included does the in mole fraction d where the reference density, the di ( mass-to-charge ratio as thewas particle operated being to trapped. trapamplitude For 18 of these measurements, NAMS and amplitude of of diameter (size selection in NAMS) and mobility diameter ( aerodynamic lens andare DIG. irradiated Particles with area then a spot captured high inside energyparticle the to laser form DIT multiply pulse charged where atomic (532 they nm, ions. The 200 ions mJpulse on are the mass basis analyzed of by mass-to-charge ratio, TOF. which can be related to mass normalized diameter rate of 5 Lmin ston, 2006; Penningtona and unipolar Johnston, charger (Chen 2012).assembly, and a It Pui, digital 1999; consists McMurry ionflectron of et guide time-of-flight al., six (DIG), 2009), (TOF) a main anlar mass digital aerodynamic components: charger analyzer. lens ion to Aerosol trap maximizeis first (DIT), the sampled passes Nd:YAG laser fraction into through and of the the a particles instrument unipo- re- that where receive particles a are collimated and focused with the 2.1 Nano Aerosol Mass Spectrometer (NAMS) Data presented in this workNAMS were obtained from with a NAMS. height Ambient of air was sampled to the 2 Methods 5 5 20 25 15 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | (2) is the average sul- sulfate is the density of condensed ect the calculated sulfuric acid ff sulfate ρ , where MF is the volume occupied by a hydrated 1 1 sulfate ν MF = 14122 14121 m Γ ) and 3 sulfate particle − ρ ρ ) (Kuwata et al., 2011), 3 × − ective gas phase sulfuric acid concentration from m ff Γ is the mean thermal speed of the condensing monomer (Kuang MEAS 1 is the density of ambient particles during the time period of interest 1 c 5 %, which is much smaller than the uncertainty of the experimental c 1 ν < 2GR is the measured growth rate, particle = ρ MEAS NAMS , ] ective sulfuric acid gas phase concentration can be calculated from the mea- the mode diameter reaches the NAMS size range. This characteristic is shown 4 ff 4 measured sulfate mass fraction SO SO Figure 1c shows the average elemental composition of 15–22 nm diameter particles Figure 1a shows particle size distributions from 3 to 100 nm over two consecutive 2 2 phase sulfuric acid concentration. Near the end of the event both decrease, but the dependence of elemental mole fraction was(Bzdek noted et previously al., for 2011, NPF 2012b). in Aprevious other remarkable work locations feature is of that Fig. 1d thebefore that change could in not elemental be studied compositionin in occurs more at detail the in onset Fig.time. of 1d Also NPF where shown the for Nmeasured reference and in with S Fig. a mole 1d chemical fractions1993; is are ionization Petaja the plotted mass et gas as al., spectrometer phase a 2009),the (CIMS) sulfuric function which particle (Eisele of acid closely and phase concentration follows Tanner, sulfur solar mole irradiance. At fraction the increases onset almost of simultaneously NPF, with the gas as a function of time. Theoxygen predominant and elements in sulfur. these The particles carbon arewhich mole carbon, fraction has nitrogen, is been anti-correlated observed withet in the al., other urban elements, 2012). locations During ascarbon mole well NPF, fraction the (Pennington is et sulfur smaller al., and than 2012; immediately nitrogen Klems before mole or fractions after are each event. larger A and similar the with the NAMS hita rate qualitative (number measure of of particleslyzed. the analyzed Both particle per events were number 10 min initiated concentration duringgrowth period), within the rate which the daylight was gives size hours. relatively On range slowreached the ana- and first the the day, the NAMS mode particle diameter sizefaster of and range the the mode near particle diameter size dusk.the passed distribution day. completely On through the the NAMS second size day, range the during growth rate was formation events are shown in Fig. 1. days where NPF was2013) observed, back 18 trajectories and indicate 19 thatpollution April air free, 2011. masses coming HYSPLIT during from (Draxler this the and time period Rolph, northwest. were Solar relatively irradiance is shown in Fig. 1b along of sulfate, ammonium and carbonaceous matter to be determined. Example particle nanoparticle elemental composition andtween in 15 this and study 22 nm was in set diameter. to The analyze elemental composition particles allows be- the mass fractions measurements. 3 Results and discussion In this study, NAMSet (Wang al., 2011, and 2012b; Johnston,et Pennington al., 2006; 2006) and Zordan is Johnston, used etland, 2012; to from obtain al., Pennington 21 single et 2008, March particle al., through mass 2010; 24 2012; spectra Bzdek April during Wang 2011. NPF in NAMS Hyytiälä, provides Fin- a quantitative measure of fate mass fraction fordoes not the include time the Fuchs–Sutugin period correctionstances of for the mass interest flux. magnitude Although (Bzdek of inin et some this the circum- al., correction particle 2012b). can sizeconcentration Equation be by range (2) substantial considered (Nieminen here et it al., would 2010), a [H where GR H et al., 2010), (estimated to be 1.3 gcm phase sulfuric acid (1.8 gcm The e sured particle phase mass fraction of sulfate by 2.2 Calculation of e 5 5 25 15 20 10 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 0.83) (Fig. 2b), = r , bisulfite and sulfite, 2 ) and the measured average sul- NAMS ] 4 SO 2 14124 14123 -line and on-line molecular composition analysis ). In both cases, the calculated sulfuric acid con- ff CIMS ] 4 SO 2 ective sulfuric acid gas phase concentration calculated from ff Similar time dependent changes in the composition of 20 nm particles are observed Table 1 gives, for each event, the measured particle growth rate and sulfate mass With the assumption that all sulfur in these particles can be assigned to sulfate, the It is reasonable to assume all of the sulfur in these particles exists in the form of suggesting that nitrogen incorporation is determined primarily by the sulfur content. acid condensation. In othermately collision words, rate sulfuric limited. acid uptake into thein particles all is eight approxi- particlein formation Fig. 2 events show as thesize shown range, approximate in as time given Fig. periods by 2. for particlesulfur particle hit (The mole rates fraction growth yellow with increases through shaded NAMS.) before therange For the regions measured seven and particle out then mode of decreases diameter eight as enters events,nitrogen the the the mole mode NAMS diameter fraction size grows is past highly this correlated range. with The sulfur change mole in fraction ( the particle phase sulfate massfuric fraction acid ([H concentration ([H centration is consistent withsimilarity the between range calculated of and measuredlink measured sulfuric between sulfuric acid acid particle concentrations. concentrations phase The confirms sulfate the mass fraction and the rate of gas phase sulfuric Since a time lagacid of concentration this and sulfur magnitude moleonset is fraction, of not mass NPF growth occurs observed primarily of between by preexistingtent sulfuric the particles with acid at increases a condensation. the This previous in observation Aerosol sulfuric isparticle Mass consis- diameters, Spectrometer as (AMS) sulfate measurement was ofincreased the NPF during first at the species larger event whose (Zhang particle-phase et concentration al., 2004a). fraction, as well as the e sation is a reasonableA explanation corollary for to the this rapidduring conclusion rise this is in time that sulfur periodrate. the mole early For mass example, fraction in if growth each the sulfate rate represented day. take event only of much must 20 longer, other % be on of chemical small the the species relative total order growth to of rate 4–5 the then h, sulfate it to would growth increase the sulfate mass fraction to 30 %. particle would remain within the NAMS size range.) Therefore, sulfuric acid conden- particle size for this level of sulfate mass growth would be about 1 nm, so the growing minen et al., 2000). sulfate mass fraction canand be compared quantitatively to determined theNPF each measured from day, the ambient the sulfate mass sulfuric sulfuristing fraction acid particle rises mole quickly at concentration. fraction from 20 At nm aroundcondensation 5 containing the at to a onset 30 the sulfate %. mass measured of If fractiontake a ambient of less preex- concentration 5 than level, % 1 we grows h calculatethe by to sulfuric that approximate increase acid it the time would sulfate period mass for fraction from which 5 this to change 30 %, occurs. which (Note is within that the change in signing sulfur from anof organosulfate total to sulfate. Finally, inorganic S(IV)which sulfate may compounds will be such significant give asPitts in a dissolved and large SO Pitts, correct particles 2000) measure or such mineralare as dust unlikely (Higashi cloud to and and constitute Takahashi, 2009; a fog Usher significant droplets et fraction al., (Finlayson- of 2003), sulfur species in ultrafine aerosol (Ker- nanoparticles, with little toet no contribution al., from 2010). other Second,ameter sulfur-containing although particles species organosulfates in (Smith some have environments beenof (Hatch detected et its in al., contribution 2011), 50–100 nm quantitativeMoreover, to if measurement di- sub organosulfates are 100 nm presentof in particles these aqueous-phase show particles, secondary they that processingand are it probably would of the is be sulfate result most low alreadyincrease significant (Lukacs contained in during sulfur in et nighttime, mole the al., fraction rather particle occurs. 2009). than Even during if daytime organosulfates when exist in the the particle, as- This slow decline ingests particle the event phase is sulfur a after regional event gas rather phase than a sulfuricsulfate local (Bzdek acid (plume) et declines event. al., sug- 2012b).of First, collected o ultrafine particles in this location show sulfate as a major constituent in change in particle composition lags the change in gas phase concentration by 3–4 h. 5 5 25 15 20 10 25 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | = r cient ammonia ffi 100 %, N mole fraction -event nighttime periods > ff ect. In contrast, AMS measurements of ff ). Another trend in Fig. 2c is that carbon 0.81). The carbon mole fraction is high at erent from composition during these three 3 ff − = 14126 14125 r 2) as predicted by AIM and indicating that su ≈ 0.87) and oxygen ( − ) than during the day when NPF occurs (and particle number concen- = 3 r -event time periods are the same. In contrast, the elemental composition of ff erent at night (when particle number concentrations are only on the order of a few Figure 3a shows the mass fractions of ammonium, sulfate and carbonaceous matter Figure 2c shows that the carbon mole fraction is anti-correlated with nitrogen ( ff 0.91), sulfur ( given as insets in Fig. 3a. These values range from 0.4 to 0.6 which is characteristic of in Fig. 2. Ammoniumdescribed and above. Carbonaceous sulfate matter are isportion given given of by by oxygen all that nitrogen carbon ismonium and in and not the sulfur sulfate assigned together particles mole to represent plus sulfate.their fractions almost the In contribution two-thirds as decreases the of to early the less portion than totalThe half mass of of remaining growth, this the and mass mass study, growth am- growth atcontribution is the of end associated of carbonaceous this with matter study. carbonaceousproduction during of matter. the volatile The organic study carbon increasing parallels as2012). increases plant The growth in apparent begins biological in oxygen the to spring carbon (Hakola (O/C) et al., mole ratios for carbonaceous matter are nanoparticles during NPF is substantiallyother di time periods. In particular,increases S by mole 50 fraction %, increases whereas by C mole fraction decreases byfor about 20 30 nm %. particles during NPF, averaged over each of the eight shaded time periods trations increase to acontent few generally thousand increases from per left cm toriod), right while (beginning sulfur to and end nitrogenposition of the during both measurement NPF decrease. pe- (average In over Fig.pared the 2d, to yellow the averages shaded over average periods three elemental inbefore non-event com- Fig. time NPF 2b periods: begins, and (1) (2) c) morninghours is hours morning on com- on non-event hours event days. on days Within experimental non-eventthe error, days, three the o elemental and compositions (3) during afternoon/evening − night when the sulfuring mole the fraction day is when lowdi NPF and occurs. then The decreases chemical (inhundred composition per relative of cm terms) 20 nm dur- particles is clearly acid concentrations (Kirkby et al., 2011). tion suggests either aan kinetic activation barrier barrier tothe ammonium for thermodynamic incorporation, ammonia endpoint for uptake by exampleaccumulation (Bzdek the due mode Kelvin to et particles e al., shownium/sulfate that 2013), mole they ratio or are fully alevels neutralized existed modification to during fully of NPF neutralize (ammo- sulfuricble acid that in the accumulation acidity mode of particles.tration the It that aerosol is is possi- at on 20 the nmconcentrations same could are order be typically as explained thought the by to sulfuric an be ammonia acid two concen- concentration. orders However, ammonia of magnitude higher than sulfuric organic nitrate (amines were not monitoredcombined during with this campaign). the These observations, strongsuggest positive that essentially correlation all between nitrogendynamic nitrogen is endpoint in and predicted the sulfur by form AIMneutralization in of is ammonium. of Fig. fully Although sulfate 2b neutralized the ammonium is thermo- sulfate, observed only during partial the eight NPF events. Partial neutraliza- mole ratio during theseorganic time nitrate, however, periods cannot averages bewhere around ruled the 1.5 out N/S and during mole never someof ratio reaches o accumulation exceeds 2. mode 2.) (In- particlesto Second, sulfate with chemical mole composition AMS ratios measurements duringaliphatic are these amines. all events Third, below show 0.1 chemicalorption that (average composition Chemical 0.06), the measurements Ionization and nitrate with Mass theresame the Spectrometer particle is (TDCIMS) Thermal size little range (Smith Des- as evidence et NAMS, for available al., only 18–19 2010) April, in show no the evidence for in- organic amines can beModel (AIM) discounted (Clegg for et several al.,the 1998) reasons. predicts range First, for of both the temperature solid Aerosol andbe and relative liquid Inorganics present humidity condensed only phases of in when thisconcentration. study the This that ammonium condition particulate concentration is nitrate is will not greater met than during twice any the of sulfate the NPF events since the N/S The likely form of this nitrogen during NPF is ammonium ion. Inorganic nitrate and 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , O 2 ternary ect may 3 ff O–NH 2 –H 4 SO 2 10.5194/acp-9-2949-2009 erences among absolute ff erences among relative growth ff vapors, J. Geophys. Res.-Atmos., 104, 3 : influence of experimental conditions, H 2 SO , 1999. 14128 14127 + erence in growth rate from one event to another O, and NH ff 2 ,H 4 SO 2 , 2006. , 2009. M. V. J. acknowledges funding from the US National Science Foundation 10.1029/1999jd900411 10.1029/2009gl038728 10.5194/acp-6-315-2006 Lee Mauldin III, R., Curtius,particle J., formation Kulmala, M., from and the Heintzenberg, reaction J.: Laboratory OH study on new ments of background2 aerosol and using new andoi: particle growth Aerodyne in Aerosol a Mass Finnish forest Spectrometer,nucleation: during initial Atmos. QUEST results Chem. for23709–23718, H doi: Phys., 6, 315–327, to new particle growth,2009. Atmos. Chem. Phys., 9, 2949–2957, doi: homogeneous nucleation rates:doi: initial observations, Geophys. Res. Lett., 36, L15818, Kulmala, M., Hyötyläinen, T., Cavalli, F., and Laaksonen, A.: Size and composition measure- Figure 3b shows particle compositions scaled to total growth rate for each of these Berndt, T., Stratmann, F.,Sipilä, M., Vanhanen, J., Petäjä, T., Mikkilä, J., Grüner, A., Spindler, G., Barsanti, K. C., McMurry, P. H., and Smith, J. N.:Benson, The D. potential R., contribution Erupe, of M. E., organic and salts Lee, S. H.: Laboratory-measured H Ball, S. M., Hanson, D. R., Eisele, F. L., and McMurry, P. H.: Laboratory studies of particle Allan, J. D., Alfarra, M. R., Bower, K. N., Coe, H., Jayne, J. T., Worsnop, D. R., Aalto, P. P., (NSF) under grant numbergrant CHE-1110554. “ATMNUCLE” M. (no. K. 22746)(project acknowledges and no. funding 1118615). the from J. Academy ERC-Advanced N.US of S. Department acknowledges Finland of support Centre Energy, fromthe grant of the DE-FG-02-05ER63997. US Saastamoinen Excellence L. NSF Foundation H. program under and sponsored R. grant by acknowledges number the support 1137757. US from TheDelaware NSF. B. National Center R. Center for B. for Critical acknowledges Atmospherichas Zone graduate not Research been fellowships Research is formally from and reviewed by the EPAEPA EPA and does University STAR the not (FP-91731501). of views endorse This expressed any are publication solely products those or of commercial the services authors. mentioned in this publication. References be substantial. Acknowledgements. tralization and acid-catalyzed SOA formation in particles where the Kelvin e future research should be directed toward chemical processes governing sulfate neu- extent to which these twothe pathways first contribute time. to Additionally, nanoparticle sulfuricthe acid growth composition is condensation of quantified is preexistingThe for shown nanoparticles relative to importance not substantially of associated SOA impact with increasesincreases. as the Nitrogen biological formation activity and in event. sulfur thesuggesting local mole that environment fractions mass in growth these bytion. However, particles ammonia these uptake particles are is are highly acidic drivenof correlated, and full by do neutralization sulfuric not to acid reach sulfate. the condensa- In thermodynamic order endpoint to understand springtime NPF more thoroughly, 4 Conclusions This study shows that particle growthboreal in forest springtime the occurs 20 by nm two size majorwith range pathways, concurrent during (1) partial NPF condensation neutralization in of by sulfuric the ammonia acid Finnish and (2) formation of “fresh” SOA. The events. These graphs show that theis di caused by a changenium, in sulfate, the carbonaceous growth matter) rateservation and of suggests that all not growth three simply by typesand/or all by of three atmospheric one matter types conditions of together of in matter (ammo- growth these is a rates alone. driven in similar This by photochemistry Fig. manner. ob- rates 3b The in Fig. are di 3a. much greater than the di The presence of freshgrowth SOA rate leaves in little these time particles formatter oxidative to is aging. aerosol The not growth high surprising is contributionsition of consistent since with carbonaceous with the AMS previous in fast measurements Hyytiälä particle of (Allan aerosol et compo- al., 2006; Raatikainen et al., 2010). “fresh” secondary organic aerosol (SOA) from biogenic sources (Jimenez et al., 2009). 5 5 30 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | – + and 4 , 2000. 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6 10 23 10 × 0.4 0.11 × ± ± 3 0.4 ± ± 6 1.0 Elemental mole fractions measured 6 6 10 10 (c) 0.10.08 3.0 0.35 × × ± ± 2 1 ± ± 1.2 Observed NAMS hit rate (particles analyzed 3 3 0.27 18 April 2011 19 April 2011 (b) 14138 14137 b a ) ) 3 3 − − a NAMS a DMPS ) 1 − ). 2 (moleccm (moleccm

CIMS NAMS ] ] 4 4 ) ) ) a b) c d SO SO

Figure 1: Figure 2 2

Experimental measurements. Calculated from Eq. ( [H Growth Rate (nmh Sulfate Mass Fraction [H 607 608 609 610 606 a b Particle size distributions for 18 and 19 April 2011. Yellow, dashed lines indicate Particle growth rate (measured), sulfate mass fraction (measured), calculated sulfuric Sulfur mole fraction (red), nitrogen mole fraction (blue), and gas phase sulfuric acid con- by NAMS, averaged over(d) 10 min periods; plots werecentration (yellow-green). subjected Mole to fraction 10 plots point were subjected boxcar to smoothing. 10-point boxcar smoothing. per 10 min period; black) and solar irradiation (yellow). approximate size range analyzed by NAMS. Fig. 1. (a) acid concentration (from particletion sulfate for mass particle fraction) formation and events measured on sulfuric 18 acid and concentra- 19 April 2011. Table 1. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper |

25 Elemental mole (b)

dN/dlogDp 24 3 3%

30x10 7%

25 20 15 10 5 0 38%

Event Days Event - 12:00 AM 20/4/2011 12:00AM 12:00AM 4/20/2011 4/20/2011 52%

of Non Afternoon/Evenings Afternoon/Evenings 12:00 AM 19/4/2011 12:00AM 12:00AM 4/19/2011 dN/dlogDp 4/19/2011 3 30x10 25 20 15 10 5 0 4% 12:00 AM

18/4/2011 7% 12:00AM 12:00AM

4/18/2011 4/18/2011 40% 40%

12:00 AM 11/4/2011 12:00AM 12:00AM 4/11/2011 4/11/2011 Event Days Event - Morning Morning of 49%

dN/dlogDp Non 12:00 AM 10/4/2011 12:00AM 12:00AM 4/10/2011 4/10/2011 3 30x10 25 20 15 10 5 0 Elemental mole fractions of carbon (green) and 9/4/2011 4/9/2011 4/9/2011 12:00 AM 12:00AM 12:00AM 3%


14140 14139 (c) 41% 41% 1/4/2011

4/1/2011 4/1/2011 12:00 AM 12:00AM 12:00AM 51% 51%

Event Days Event Morning Morning of 12:00AM 12:00AM 12:00 AM 3/31/2011 3/31/2011 31/3/2011

12:00AM 12:00AM 3/30/2011 3/30/2011 12:00 AM 30/3/2011 7%


12:00AM 12:00AM 3/29/2011 3/29/2011

12:00 AM 29/3/2011 45%

12:00AM 12:00AM 3/28/2011 3/28/2011 12:00 AM 28/3/2011

0.6 0.5 0.4 0.3 0.2 38%

0.16 0.14 0.12 0.10 0.08 0.06 0.04 0.02 0.00 0.10 0.08 0.06 0.04 0.02

Event Periods Event Mole Fraction Mole Particle Diameter (µm) Diameter Particle Mole Fraction Mole

) ) d b) c a) Mass growth rates of sulfate, ammonium and carbonaceous matter for the

Figure 2: Figure

(b) 613 614 611 612 Average elemental compositions of particles sampled during NPF events, in the

(d) Particle size distributions for eight days when NPF occurred. Mass fractions of sulfate, ammonium and carbonaceous matter for eight NPF events b) a)

Figure 3: Figure

616 617 618 615 Fig. 3. (a) during the measurement campaign.that The event numerical period. value insetsame in NPF each events. bar Molecular isfor composition the measurement O/C uncertainties of elemental ratio are nitrogen for based and on sulfur (10 assigned %). uncertainties Fig. 2. (a) fractions of nitrogen (blue) andoxygen sulfur (violet). (red). Elemental mole fractions wereregions subjected show to approximate 10-point time boxcar periods smoothing;size when shaded range. the particle mode diametermornings was of within the event NAMS days (02:00–09:00and LT), in in the the afternoons/evenings mornings of of non-event non-event days days (10:00–22:00 LT). (02:00–09:00 LT)