Integration of size distributions and size-resolved hygroscopicity measured during the Houston Supersite for compositional categorization of the aerosol

Gasparini, Roberto; Li, Runjun; Collins, D. R.

doi:10.1016/j.atmosenv.2004.03.019

Cited by 69 publications

(58 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Specific details of HTDMA1, HTDMA2 and HT-DMA3 can be found in Duplissy et al (2008Duplissy et al ( , 2009, Gasparini et al (2004) and Sjogren et al (2008) respectively. The residence times of the aerosol in the humidifier, the chosen RH and the operating temperature were (15 s, 95%, 20 • C), (10 s, 85%, 40 • C) and (20 s, 85%, 25 • C), respectively.…”

Section: Htdmamentioning

confidence: 99%

Relating hygroscopicity and composition of organic aerosol particulate matter

et al. 2011

View full text Add to dashboard Cite

Abstract.A hygroscopicity tandem differential mobility analyzer (HTDMA) was used to measure the water uptake (hygroscopicity) of secondary organic aerosol (SOA) formed during the chemical and photochemical oxidation of several organic precursors in a smog chamber. Electron ionization mass spectra of the non-refractory submicron aerosol were simultaneously determined with an aerosol mass spectrometer (AMS), and correlations between the two different signals were investigated. SOA hygroscopicity was found to strongly correlate with the relative abundance of the ion signal m/z 44 expressed as a fraction of total organic signal (f 44 ). m/z 44 is due mostly to the ion fragment CO + 2 for all types of SOA systems studied, and has been previously shown to strongly correlate with organic O/C for ambient and chamber OA. The analysis was also performed on ambient OA from two field experiments at the remote site Jungfraujoch, and the megacity Mexico City, where similar results were found. A simple empirical linear relation between the hygroscopicity of OA at subsaturated RH, as given by the hygroscopic growth factor (GF) or "κ org " parameter, and f 44 was determined and is given by κ org = 2.2× f 44 − 0.13. This approximation can be further verified and refined as the Correspondence to: J. Duplissy (jonathan.duplissy@cern.ch) database for AMS and HTDMA measurements is constantly being expanded around the world. The use of this approximation could introduce an important simplification in the parameterization of hygroscopicity of OA in atmospheric models, since f 44 is correlated with the photochemical age of an air mass.

show abstract

Section: Htdmamentioning

confidence: 99%

Relating hygroscopicity and composition of organic aerosol particulate matter

et al. 2011

View full text Add to dashboard Cite

show abstract

“…The size-resolved aerosol hygroscopicity, from which aerosol mixing state is inferred, was measured by a Tandem Differential Mobility Analyzer (TDMA) system (Gasparini et al, 2004). In the TDMA, the classifying voltage of the first DMA is held constant to select a monodisperse aerosol of dry diameter D * p .…”

Section: Aerosol Hygroscopic Growth Factor Distribution and Mixing Statementioning

confidence: 99%

The importance of aerosol mixing state and size-resolved composition on CCN concentration and the variation of the importance with atmospheric aging of aerosols

et al. 2010

View full text Add to dashboard Cite

The aerosol size distribution and composition often showed strong diurnal variation associated with traffic emissions and aging of aerosols through coagulation and local photochemical production of secondary aerosol species. CCN concentrations (N CCN ) are derived using Köhler theory from the measured aerosol size distribution and various simplified aerosol mixing state and chemical composition, and are compared to concurrent measurements at five supersaturations ranging from 0.11% to 0.35%. The influence of assumed mixing state on calculated N CCN is examined using both aerosols observed during MILAGRO and representative aerosol types. The results indicate that while ambient aerosols often consist of particles with a wide range of compositions at a given size, N CCN may be derived within ∼20% assuming an internal mixture (i.e., particles at a given size are mixtures of all participating species, and have the identical composition) if great majority of particles has an overall κ (hygroscopicity parameter) value greater than 0.1. For a non-hygroscopic particle with a diameter of 100 nm, a 3 nm coating of sulfate or nitrate is sufficient to increase its κ from 0 to 0.1. The measurements during MILAGRO suggest that the mixing of non-hygroscopic primary organic aerosol (POA) and black carbon (BC) particles with photochemically produced hygroscopic species and thereby the increase of their κ to 0.1 take place in a few hours during daytime. This rapid process suggests that during daytime, a few tens of kilometers away for Correspondence to: J. Wang (jian@bnl.gov) POA and BC sources, N CCN may be derived with sufficient accuracy by assuming an internal mixture, and using bulk chemical composition. The rapid mixing also indicates that, at least for very active photochemical environments such as Mexico City, the timescale during daytime for the conversion of hydrophobic POA and BC to hydrophilic particles is substantially shorter than the 1-2 days used in some global models. The conversion time scale is substantially longer during night. Most POA and BC particles emitted during evening hours likely remain non-hygroscopic until efficiently internally mixed with secondary species in the next morning. The results also suggest that the assumed mixing state strongly impacts calculated N CCN only when POA and BC represent a large fraction of the total aerosol volume. One of the implications is that while physically unrealistic, external mixtures, which are used in many global models, may also sufficiently predict N CCN for aged aerosol, as the contribution of nonhygroscopic POA and BC to overall aerosol volume is often substantially reduced due to the condensation of secondary species.

show abstract

“…90 The higher water content in the summer was likely due to the higher levels of water-soluble species ((NH 4 ) 2 SO 4 , NH 4 HSO 4 , and SVOC) versus higher levels of primary OC in the winter, similar to results observed in Houston. 293 Results for 1 week in July showed an aerosol water content ranging from 0 to 50% or 0 to 20 g/m 3 of water at RH values below 90%, with PM 2.5 mass concentrations ranging from around 5-60 g/m 3 , indicating that water can vary significantly during short time periods. 117 Rees et al 90 used continuous composition data and PBW (DAASS) measurements relative to mass measured by the SES-TEOM and was able to close the mass balance for aerosols collected in July 2001 at the Pittsburgh Supersite on an hourly basis.…”

Section: Aerosol Water and Pm 25 Mass Balancementioning

confidence: 99%

“…293 Measurements were in eight discrete particle sizes in the range from 25 to 700 nm. Hygroscopicity increased with increasing particle size, which suggested that condensation of less hygroscopic primary organic compounds onto the smallest particles measured (25 nm) was responsible for initial growth, noting that little is known about the initial particles smaller than 25 nm.…”

Section: Aerosol Water and Pm 25 Mass Balancementioning

confidence: 99%