On the photochemical production of new particles in the coastal boundary layer

O’Dowd, Colin; McFiggans, G.; Creasey, D. J.; Pirjola, Liisa; Hoell, Claudia; Smith, Michael H.; Allan, B. J.; Plane, J. M. C.; Heard, D. E.; Lee, James; Pilling, Michael J.; Kulmala, Markku

doi:10.1029/1999gl900335

Cited by 218 publications

(190 citation statements)

References 11 publications

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“…Our current understanding of atmospheric nanoparticle processes suggests that growth of these particles to larger sizes within the ultrafine PM mode occurs by condensation of low volatility organic species. These species are products of photochemical oxidation of volatile organic precursors on these pre-existing nuclei (O'Dowd et al, 1999;Kulmala et al, 2004). In fact, recent studies by Zhang et al (2004) showed that nucleation rates of sulfuric acid are greatly increased in the presence of organic acids (including products of atmospheric photochemical reactions), by forming unusually stable organic-sulfuric acid complexes, thereby reducing the nucleation barrier of sulfuric acid.…”

Section: Discussionmentioning

confidence: 99%

“…During summer months, secondary aerosol formation is favored and new ultrafine particles may form as a result of the condensation of low-volatility products of photochemical reactions (largely organic compounds) onto stable, nanometer-size particles (O'Dowd et al, 1999;Kim et al, 2002;Sardar et al, 2004). Secondary aerosol formation is the most likely explanation for the diurnal trends in PN during the summer period at USC and Long Beach (Figures 4b and 5b, respectively) in which the peak particle concentrations during the afternoon period either coincide or slightly lag behind the peak in O 3 concentrations.…”

Section: Diurnal Trendsmentioning

confidence: 99%

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Seasonal and spatial trends in particle number concentrations and size distributions at the children's health study sites in Southern California

Singh

Phuleria

Bowers

et al. 2005

J Expo Sci Environ Epidemiol

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Section: Discussionmentioning

confidence: 99%

Section: Diurnal Trendsmentioning

confidence: 99%

Seasonal and spatial trends in particle number concentrations and size distributions at the children's health study sites in Southern California

Singh

Phuleria

Bowers

et al. 2005

J Expo Sci Environ Epidemiol

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“…[13] Newly formed particles by homogeneous nucleation of water and sulfuric acid, in presence of ammonia and other organic species, tend to have very small sizes (d p $ 2 nm) [Covert et al, 1992;Mäkelä et al, 1997;Marti et al, 1997;Weber et al, 1997Weber et al, , 1998Kulmala et al, 1998;O'Dowd et al, 1999;Clarke et al, 1998]. It has been shown that the nucleation rate can be enhanced by the presence of organics and ions [Yu et al, 1999;Yu and Turco, 2000].…”

Section: Growth Rate Of Ufpmentioning

confidence: 99%

Precipitation removal of ultrafine aerosol particles from the atmospheric boundary layer

Andronache

2004

J. Geophys. Res.

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[1] Ultrafine particles (UFP) formed in the boundary layer (BL) by nucleation processes need to grow up to a diameter d p $ 100 nm to become activated as cloud droplets (CD). The time required to reach d p = 100 nm is about 2-3 days for a typical growth rate of 5 nm h À1 . If precipitation occurs, most UFP are too small to become CD, and some particles are removed by scavenging processes. A model to estimate the UFP wet removal from the BL by rainfall and coagulation is presented. The scavenging coefficient that describes the decay of aerosol mass in various size bins is a function of aerosol size (d p ), rainfall rate (R), and BL background aerosol. The model is applied to determine the UFP 0.5-folding time (t 05 ) during rain events and results show that t 05 $ 1 hour for R $ 1 mm h À1 for newly created particles (d p < 10 nm) and t 05 $ 1 day for larger UFP (d p $ 10-100 nm). To infer the likelihood of UFP removal at a given location, the average time interval (Dt) between rain events with rainfall rate R = 1 mm h À1 at stations with different precipitation regimes was determined. Results show that on average, UFP are very effectively removed from the BL by below-cloud scavenging in tropical regions (Dt $ 1 day), removed to a significant extent in eastern U.S. regions (Dt $ 3 days), and are less likely to be removed in southwest U.S. regions (Dt $ 6-8 days), where the frequency of dry periods is high and UFP have sufficient time to grow.

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“…[7] Two types of nucleation events have been observed in which the main condensing species are not sulfuric acid and ammonia: in Finnish forests [Mäkelä et al, 1997] and off the Irish coast [O'Dowd et al, 1999]. Their characteristics, covering many events, have been explored in large cooperative European campaigns, Biogenic Aerosol Formation in the Boreal Forest (BIOFOR) and New Particle Formation and Fate in the Coastal Environment (PARFORCE), whose results have recently been reported [Kulmala and Hämeri, 2000;O'Dowd and Hämeri, 2000].…”

Section: Previous Workmentioning

confidence: 99%

Deep convection as a source of new particles in the midlatitude upper troposphere

et al. 2002

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[1] A case study of new particle formation in the region downwind of a mesoscale convective system stretching across much of the central United States is presented. Airborne measurements were made of condensation nuclei (CN), cloud particle surface area, water vapor, and other gases. CN concentrations were greatly enhanced above and downwind of the cirrus anvil, with maximum concentrations of 45,000 per standard cm 3 . Volatility and electron microscope measurements indicated that most of the particles were likely to be small sulfate particles. The enhancement extended over at least a 600-km region. Multivariate statistical analysis revealed that high CN concentrations were associated with surface tracers, as well as convective elements. Convection apparently brings gas-phase particle precursors from the surface to the storm outflow region, where particle nucleation is favored by the extremely low temperatures. Simple calculations showed that deep convective systems may contribute to a substantial portion of the background aerosol in the upper troposphere at midlatitudes.

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On the photochemical production of new particles in the coastal boundary layer

Abstract: Abstract.Concurrent measurements of ultra-fine (r<5 nm)

Cited by 218 publications

References 11 publications

Seasonal and spatial trends in particle number concentrations and size distributions at the children's health study sites in Southern California

Seasonal and spatial trends in particle number concentrations and size distributions at the children's health study sites in Southern California

Precipitation removal of ultrafine aerosol particles from the atmospheric boundary layer

Deep convection as a source of new particles in the midlatitude upper troposphere

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