The investigations of aerosol particle formation in urban background area of Helsinki

Hämeri, Kaarle; Kulmala, Markku; Aalto, Pasi; Leszczynski, Kirsti; Visuri, Reijo; Hämekoski, Kari

doi:10.1016/0169-8095(96)00015-4

Cited by 36 publications

(18 citation statements)

References 11 publications

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“…New particle formation (NPF) and growth are a major source for ultra fine particles (UFP) in both clean and polluted atmospheres. NPF is also important for sustaining the ambient aerosol populations, not only in forested (Kulmala et al, 1998; Pirjola et al, 1998), coastal (O’Dowd et al, 1998; O’Dowd et al, 2002), rural/remote (Eisele and McMurry, 1997; Weber et al, 1999; Wiedensohler et al, 2002), arctic (Pirjola et al, 1998) and urban (Hämeri et al, 1996; Wiedensohler et al, 2002; Alam et al, 2003; Zhang et al, 2004a) areas, but also in mega cities such as Mexico City (Dunn et al, 2004), Beijing (Wehner et al, 2004) and New Delhi (Mönkkönen et al, 2005). Newly formed particles can grow into larger particles (>100 nm) in 1–2 d (Kulmala et al, 2004), and they may thus influence regional climate due to their effects on cloud formation, solar radiation and visibility.…”

Section: Introductionmentioning

confidence: 99%

Characterization of new particle and secondary aerosol formation during summertime in Beijing, China

Zhang

Zhang²,

Sun³

et al. 2011

Tellus B: Chemical and Physical Meteorology

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A B S T R A C T Size-resolved aerosol number and mass concentrations and the mixing ratios of O 3 and various trace gases were continuously measured at an urban station before and during the Beijing Olympic and Paralympic Games (5 June to 22 September, 2008). 23 new particle formation (NPF) events were identified; these usually were associated with changes in wind direction and/or rising concentrations of gas-phase precursors or after precipitation events. Most of the NPF events started in the morning and continued to noon as particles in the nucleation mode grew into the Aitken mode. From noon to midnight, the aerosols grew into the accumulation mode through condensation and coagulation. Ozone showed a gradual rise starting around 10:00 local time, reached its peak around 15:00 and then declined as the organics increased. The dominant new particle species were organics (40-75% of PM 1 ) and sulphate; nitrate and ammonium were more minor contributors.

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Section: Introductionmentioning

confidence: 99%

Characterization of new particle and secondary aerosol formation during summertime in Beijing, China

Zhang

Zhang²,

Sun³

et al. 2011

Tellus B: Chemical and Physical Meteorology

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“…The UF-TDMA measurements were performed in February 1997. More details about the downtown Helsinki and Luukki sites can be found in Hämeri et al (1996), Buzorius et al (1999) and Väkevä et al (2000).…”

Section: Measurement Sitesmentioning

confidence: 99%

Field measurements of hygroscopic properties and state of mixing of nucleation mode particles

et al. 2002

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Abstract. An Ultrafine Tandem Differential Mobility Analyser (UF-TDMA) has been used in several field campaigns over the last few years. The investigations were focused on the origin and properties of nucleation event aerosols, which are observed frequently in various environments. This paper gives a summary of the results of 10 nm and 20 nm particle hygroscopic properties from different measurement sites: an urban site, an urban background site and a forest site in Finland and a coastal site in western Ireland. The data can be classified in four hygroscopic growth classes: hydrofobic, less-hygroscopic, more-hygroscopic and sea-salt. Similar classification has been earlier presented for Aitken and accumulation mode particles. In urban air, the summertime 10 nm particles showed varying less-hygroscopic growth behaviour, while winter time 10 nm and 20 nm particles were externally mixed with two different hygroscopic growth modes. The forest measurements revealed diurnal behaviour of hygroscopic growth, with high growth factors at day time and lower during night. The urban background particles had growth behaviour similar to the urban and forest measurement sites depending on the origin of the observed particles. The coastal measurements were strongly affected by air mass history. Both 10 nm and 20 nm particles were hygroscopic in marine background air. The 10 nm particles produced during clean nucleation burst periods were hydrofobic. Diurnal variation and higher growth factors of 10 nm particles were observed in air affected by other source regions. External mixing was occasionally observed at all the sites, but incidents with more than two growth modes were Correspondence to: K. Hämeri (kaarle.hameri@occuphealth.fi) extremely rare.

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“…Numerous aerosol number size distribution and number concentration measurements has been conducted in urban environments in developed countries like United States, United Kingdom, Germany and Finland (Hämeri et al, 1996;Williams et al, 1998;Shi et al, 2001;Woo et al, 2001;Wehner et al, 2002;Longley et al, 2003). The studies that have examined number size distribution or number conCorrespondence to: P. Mönkkönen (petteri.monkkonen@helsinki.fi) centration of aerosols in Asia, Latin America or Africa are very few (Baumgardner et al, 2000;Jayaratne and Verma, 2001;Mitra and Sharma, 2002;Mönkkönen et al, 2004a;Mönkkönen et al, 2004b;Mönkkönen et al, 2005) even though the air pollution problem is particularly serious in the mega cities of South and East Asia.…”

Section: Introductionmentioning

confidence: 99%

Measurements in a highly polluted Asian mega city: observations of aerosol number size distribution, modal parameters and nucleation events

et al. 2005

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Abstract. Diurnal variation of number size distribution (particle size 3-800 nm) and modal parameters (geometric standard deviation, geometric mean diameter and modal aerosol particle concentration) in a highly polluted urban environment was investigated during October and November 2002 in New Delhi, India. Continuous monitoring for more than two weeks with the time resolution of 10 min was conducted using a Differential Mobility Particle Sizer (twin DMPS). The results indicated clear increase in Aitken mode (25-100 nm) particles during traffic peak hours, but towards the evenings there were more Aitken mode particles compared to the mornings. Also high concentrations of accumulation mode particles (>100 nm) were detected in the evenings only. In the evenings, biomass/refuse burning and cooking are possible sources beside the traffic. We have also shown that nucleation events are possible in this kind of atmosphere even though as clear nucleation events as observed in rural sites could not be detected. The formation rate of 3 nm particles (J3) of the observed events varied from 3.3 to 13.9 cm −3 s −1 and the growth rate varied from 11.6 to 18.1 nmh −1 showing rapid growth and high formation rate, which seems to be typical in urban areas.

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The investigations of aerosol particle formation in urban background area of Helsinki

Cited by 36 publications

References 11 publications

Characterization of new particle and secondary aerosol formation during summertime in Beijing, China

Characterization of new particle and secondary aerosol formation during summertime in Beijing, China

Field measurements of hygroscopic properties and state of mixing of nucleation mode particles

Measurements in a highly polluted Asian mega city: observations of aerosol number size distribution, modal parameters and nucleation events

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