Effects of meteorological processes on aerosol particle size distribution in an urban background area

Väkevä, M.; Hämeri, Kaarle; Puhakka, Timo; Nilsson, E. Douglas; Hohti, Harri; Mäkelä, Jyrki M.

doi:10.1029/1999jd901143

Cited by 107 publications

(54 citation statements)

References 23 publications

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“…The temporal variations in the hygroscopic properties of 10 nm particles during the nucleation event day were very similar to the nucleation event days in Hyytiälä: The growth factors are low in the morning prior to the nucleation event, they gradually increase just before and during the nucleation and decrease again in the afternoon (Hämeri et al, 2001b). The new particle formation events have been described in more detail in Väkevä et al (2000).…”

Section: Urban Background Sitementioning

confidence: 62%

“…The characteristics of the nucleation events are described in, e.g. Mäkelä et al (1997), O'Dowd et al (1998) and Väkevä et al (2000). Apparently, the nucleation in atmosphere is important source for new particles.…”

Section: Discussionmentioning

confidence: 99%

“…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%

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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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Section: Urban Background Sitementioning

confidence: 62%

Section: Discussionmentioning

confidence: 99%

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

et al. 2002

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“…Particle concentrations are also affected by local mixing. If the boundary layer is stable, locally emitted or re-suspended particles stay in a smaller volume (Väkevä et al, 2000). In practice, mixing depend on wind speed, turbulence, and relative humidity (Pohjola et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

Urban aerosol number size distributions

et al. 2004

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Abstract. Aerosol number size distributions have been measured since 5 May 1997 in Helsinki, Finland. The presented aerosol data represents size distributions within the particle diameter size range 8-400 nm during the period from May 1997 to March 2003. The daily, monthly and annual patterns of the aerosol particle number concentrations were investigated. The temporal variation of the particle number concentration showed close correlations with traffic activities. The highest total number concentrations were observed during workdays; especially on Fridays, and the lowest concentrations occurred during weekends; especially Sundays. Seasonally, the highest total number concentrations were observed during winter and spring and lower concentrations were observed during June and July. More than 80% of the number size distributions had three modes: nucleation mode (D p <30 nm), Aitken mode (20-100 nm) and accumulation mode (D p >90 nm). Less than 20% of the number size distributions had either two modes or consisted of more than three modes. Two different measurement sites were used; in the first (Siltavuori, 5.5.1997(Siltavuori, 5.5. -5.3.2001, the arithmetic means of the particle number concentrations were 7000 cm −3 , 6500 cm −3 , and 1000 cm −3 respectively for nucleation, Aitken, and accumulation modes. In the second site (Kumpula, 6.3.2001(Kumpula, 6.3. -28.2.2003) they were 5500 cm −3 , 4000 cm −3 , and 1000 cm −3 . The total number concentration in nucleation and Aitken modes were usually significantly higher during workdays than during weekends. The temporal variations in the accumulation mode were less pronounced. The lower concentrations at Kumpula were mainly due to building construction and also the slight overall decreasing trend during these years. During the site changing a period of simultaneous measurements over two weeks were performed showing nice correlation at both sites.

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“…In one study (Väkevä et al 2000), it was found that the wind direction weighs heavily in shaping particle number size distributions in the urban background area of Helsinki, Finland. Other studies have reported that long-range transport also plays a vital role in changing the particle number concentrations (Tiitta et al 2002;Niemi et al 2004).…”

Section: Introductionmentioning

confidence: 99%

Characteristics and composition of the falling dust in urban environment

Al‐Harbi

2013

Int. J. Environ. Sci. Technol.

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The monthly total amount of dust fall, as well as its chemical and physical characteristics, was systematically investigated in Shuwaikh city, Kuwait. Dust samples were collected on a monthly basis for the entire year of 2009 and analyzed in the laboratory for water-soluble and water-insoluble matter. Water-insoluble matter represented the major portion of the total annual dust. ANOVAs showed significant temporal variation in the concentration of dust fall over the months (p \ 0.05). Higher dust deposits were encountered between June and August and ranged from 76.4 to 97.6 ± 2.5 (SD) ton km -2 month -1 , where dusty winds and low humidity are a common attribute in such arid areas. The main three soluble matter species measured are nitrate, sulfate, and chloride, and sulfate was found to be the most abundant inorganic species, ranging from 0.72 ± 0.13 to 4.1 ± 0.3 ton km -2 -month -1 . Major insoluble matter species measured are ash, silica, combustible, and tarry. Ash, silica, and combustible account for 63, 19, and 17.8 % of total insoluble dust, and 58.4, 17.7, and 16.6 % of total dust, respectively. Particle size distribution was also investigated, and results showed that dust particles[7 lm were the highest concentration of falling dust. Metrological conditions were found to play a vital role in temporal variations in falling dust.

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Effects of meteorological processes on aerosol particle size distribution in an urban background area

Cited by 107 publications

References 23 publications

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

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

Urban aerosol number size distributions

Characteristics and composition of the falling dust in urban environment

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