Nocturnal new particle formation events in urban environments

Salimi, Farhad; Rahman, Mahmudur; Clifford, Samuel; Ristovski, Zoran; Morawska, Lidia

doi:10.5194/acp-17-521-2017

Cited by 28 publications

(21 citation statements)

References 48 publications

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“…(1), varied between 4 and 22 nm h −1 with a mean and standard deviation of (12.1 ± 6.5) nm h −1 . These growth rates were comparable to the values reported at two other urban locations; Atlanta, USA (3-20 nm h −1 ) (Stolzenburg et al, 2005) and Budapest, Hungary (2-13 nm h −1 ) (Salma et al, 2011). However, the mean values of growth rates obtained by previous studies in Brisbane were significantly lower than the value reported by this study.…”

Section: Day Time and Night Time Npf Eventssupporting

confidence: 84%

Differentiating between particle formation and growth events in an urban environment

2018

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Abstract. Small aerosols at a given location in the atmosphere often originate in situ from new particle formation (NPF). However, they can also be produced and then transported from a distant location to the point of observation where they may continue to grow to larger sizes. This study was carried out in the subtropical urban environment of Brisbane, Australia, in order to assess the relative occurrence frequencies of NPF events and particle growth events with no NPF. We used a neutral cluster and air ion spectrometer (NAIS) to monitor particles and ions in the size range 2–42 nm on 485 days, and identified 236 NPF events on 213 days. The majority of these events (37 %) occurred during the daylight hours with just 10 % at night. However, the NAIS also showed particle growth with no NPF on many nights (28 %). Using a scanning mobility particle sizer (SMPS), we showed that particle growth continued at larger sizes and occurred on 70 % of nights, typically under high relative humidities. Most particles in the air, especially near coastal locations, contain hygroscopic salts such as sodium chloride that may exhibit deliquescence when the relative humidity exceeds about 75 %. The growth rates of particles at night often exceeded the rates observed during NPF events. Although most of these night time growth events were preceded by day time NPF events, the latter was not a prerequisite for growth. We conclude that particle growth in the atmosphere can be easily misidentified as NPF, especially when they are monitored by an instrument that cannot detect them at the very small sizes.

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Section: Day Time and Night Time Npf Eventssupporting

confidence: 84%

Differentiating between particle formation and growth events in an urban environment

2018

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“…S3). Salimi et al (2017) reported nocturnal new particle formation events in Brisbane, Australia, finding that air masses associated with nocturnal events were typically transported over the ocean before reaching their sampling site, but the relevance to our study is unclear, although the maritime air might sometimes be expected to show lower temperature and higher humidity than that from the land.…”

Section: Particle Number Concentration (Cpc) Datamentioning

confidence: 83%

“…This appears to require growth of sub-2.5 nm particles into the range measured by CPC in the cooler, more humid nocturnal conditions. Rönkkö et al (2006) and Schneider et al (2005) studied the formation of mechanisms and composition of diesel exhaust nucleation particles in the laboratory and during car chasing. They conclude that formation of nucleation mode particles depends upon formation of sulfate nuclei upon which hydrocarbons condense, consistent with earlier studies of Shi and Harrison (1999) and conducted in our laboratory.…”

Section: Particle Number Concentration (Cpc) Datamentioning

confidence: 99%

Interpretation of particle number size distributions measured across an urban area during the FASTER campaign

et al. 2019

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Abstract. Particle number size distributions have been measured simultaneously by scanning mobility particle sizers (SMPSs) at five sites in central London for a 1 month campaign in January–February 2017. These measurements were accompanied by condensation particle counters (CPCs) to measure total particle number count at four of the sites and Aethalometers measuring black carbon (BC) at five sites. The spatial distribution and inter-relationships of the particle size distribution and SMPS total number counts with CPC total number counts and black carbon measurements have been analysed in detail as well as variations in the size distributions. One site (Marylebone Road) was in a street canyon with heavy traffic, one site (Westminster University) was on a rooftop adjacent to the Marylebone Road sampler, and a further sampler was located at Regent's University within a major park to the north of Marylebone Road. A fourth sampler was located nearby at 160 m above ground level on the BT tower and a fifth sampler was located 4 km to the west of the main sampling region at North Kensington. Consistent with earlier studies it was found that the mode in the size distribution had shifted to smaller sizes at the Regent's University (park) site, the mean particle shrinkage rate being 0.04 nm s−1 with slightly lower values at low wind speeds and some larger values at higher wind speeds. There was evidence of complete evaporation of the semi-volatile nucleation mode under certain conditions at the elevated BT Tower site. While the SMPS total count and black carbon showed typical traffic-dominated diurnal profiles, the CPC count data typically peaked during night-time as did CPC∕SMPS and CPC∕BC ratios. This is thought to be due to the presence of high concentrations of small particles (2.5–15 nm diameter) probably arising from condensational growth from traffic emissions during the cooler night-time conditions. Such behaviour was most marked at the Regent's University and Westminster University sites and less so at Marylebone Road, while at the elevated BT Tower site the ratio of particle number (CPC) to black carbon peaked during the morning rush hour and not at night-time, unlike the other sites. An elevation in nucleation mode particles associated with winds from the west and WSW sector was concluded to result from emissions from London Heathrow Airport, despite a distance of 22 km from the central London sites.

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“…However, there is evidence from aircraft measurements over a large range of latitudes and altitudes that nucleation also takes place during the night in the free troposphere (Hermann et al, 2003;Lee et al, 2008). Observations at the ground level have shown some nighttime particle formation events at different locations (Buenrostro Mazon, 2016;Duplissy et al, 2008;Junninen et al, 2008;Kalivitis et al, 2012;Lehtipalo et al, 2011;Liu et al, 2014;Man et al, 2015;Ortega et al, 2009;Ortega et al, 2012;Pushpawela et al, 2018;Rose et al, 2018;Russell et al, 2007;Salimi et al, 2017;Suni et al, 2008;Svenningsson et al, 2008;Wiedensohler et al, 1997;Zhu et al, 2014). Nighttime nucleation is characterized by enhanced nuclei mode particle concentrations, but they usually do not show the typical "banana" shaped growth as seen during the daytime NPF events.…”

Section: Nighttime Nucleationmentioning

confidence: 99%

New Particle Formation in the Atmosphere: From Molecular Clusters to Global Climate

et al. 2019

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New particle formation (NPF) represents the first step in the complex processes leading to formation of cloud condensation nuclei. Newly formed nanoparticles affect human health, air quality, weather, and climate. This review provides a brief history, synthesizes recent significant progresses, and outlines the challenges and future directions for research relevant to NPF. New developments include the emergence of state‐of‐the‐art instruments that measure prenucleation clusters and newly nucleated nanoparticles down to about 1 nm; systematic laboratory studies of multicomponent nucleation systems, including collaborative experiments conducted in the Cosmics Leaving Outdoor Droplets chamber at CERN; observations of NPF in different types of forests, extremely polluted urban locations, coastal sites, polar regions, and high‐elevation sites; and improved nucleation theories and parameterizations to account for NPF in atmospheric models. The challenges include the lack of understanding of the fundamental chemical mechanisms responsible for aerosol nucleation and growth under diverse environments, the effects of SO2 and NOx on NPF, and the contribution of anthropogenic organic compounds to NPF. It is also critical to develop instruments that can detect chemical composition of particles from 3 to 20 nm and improve parameterizations to represent NPF over a wide range of atmospheric conditions of chemical precursor, temperature, and humidity.

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Nocturnal new particle formation events in urban environments

Cited by 28 publications

References 48 publications

Differentiating between particle formation and growth events in an urban environment

Differentiating between particle formation and growth events in an urban environment

Interpretation of particle number size distributions measured across an urban area during the FASTER campaign

New Particle Formation in the Atmosphere: From Molecular Clusters to Global Climate

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