Characteristics of formation and growth of atmospheric nanoparticles observed at four regional background sites in Korea

doi:10.1016/j.atmosres.2015.08.020

Atmospheric Research

Volume 168, 1 February 2016, Pages 80-91

https://doi.org/10.1016/j.atmosres.2015.08.020 Get rights and content

Highlights

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NPF events were investigated at four sites on the west coast of the Korean Peninsula.
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NPF was simultaneously observed for five days at all four sites (~ 540 km).
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A cold and dry air mass from northern China formed favorable conditions for NPF.
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The mean FRs at BCMO and KGAWC were relatively higher than those at GCO and JCMO.

Abstract

Measurements of the number concentration and size distribution of atmospheric nanoparticles were conducted at four sites on the west coast of the Korean Peninsula by using identical scanning mobility particle sizers (SMPSs) in October 2012. The new particle formation and subsequent growth (NPF) of atmospheric nanoparticles, which were identified by the cyclostationary empirical orthogonal function (CSEOF) analysis technique, was observed on 11 out of 21 days at the Baengnyeong-do Comprehensive Monitoring Observatory (BCMO); and on 10 out of 21 days at the Korea Global Atmosphere Watch Center (KGAWC) from October 9 to 29, 2012. We also observed NPF events for 9 out of 21 days at both the Gosan Climate Observatory (GCO) and the Jeju Comprehensive Monitoring Observatory (JCMO). During the study period, NPF was simultaneously observed for five days at all four sites, which indicates that the NPF event had a spatial extent of at least 540 km.

A cold, dry and cloud-free continental air mass originated from northern China, formed favorable environmental conditions (e.g., increasing solar insolation at the surface) on simultaneous NPF at the four sites. These synoptic weather patterns were closely associated with an extraordinary typhoon passing over the south of Japan. The mean values of particle formation rates at BCMO (1.26 cm^− 3 s^− 1) and KGAWC (1.49 cm^− 3 s^− 1) were relatively higher than those at GCO (0.39 cm^− 3 s^− 1) and JCMO (0.74 cm^− 3 s^− 1), however, the growth rate showed a similar level among four sites. An increase in the spatial homogeneity and inter-site correlation of atmospheric particles among the four sites was apparent for small particles (diameter < 30 nm) on simultaneous NPF event days.

Introduction

The nucleation and subsequent growth of atmospheric nanoparticles are important processes of accumulation-mode aerosol formation in the troposphere (Deshpande et al., 2014, Merikanto et al., 2009, Yu et al., 2008). These newly formed particles can grow into larger-sized particles, which can directly alter incoming solar radiation and act as potential cloud condensation nuclei (Kerminen et al., 2012, Kuwata et al., 2008).

The formation and subsequent growth of atmospheric particles have been observed under various environmental conditions and spatial scales (Arizabalo et al., 2015, Kanawade et al., 2014, Kulmala and Kerminen, 2008, Kulmala et al., 2004, Mbengue et al., 2014, Minguillón et al., 2015, Siingh et al., 2013, Wang et al., 2014, Zhao et al., 2015). Hussein et al. (2009) investigated long-term measurements of particle number size distributions at five widely separated background sites in Finland, Sweden, and Estonia and reported that new particle formation and subsequent growth (hereafter, NPF) events took place over the entire study region, where the combined horizontal distance among the sites was up to ~ 1500 km. Air masses transported from the Arctic region formed favorable environmental conditions for NPF (Nilsson et al., 2001a, Nilsson et al., 2001b, Sogacheva et al., 2008). Jeong et al. (2010) determined that distinctive NPF events were apparent simultaneously at five rural and urban sites, which were up to 350 km away, in Ontario, Canada. These regional NPF events were closely associated with intense solar irradiance and less polluted, cold, and dry air masses. Simultaneous NPF events were also observed in the polluted urban and regional background stations, which were separated by approximately 120 km, in the North China Plain (Wang et al., 2013). The conditions of the NPF event in the North China Plain could be characterized as higher precursor vapor concentration and pre-existing particles, even in the regional background environment.

Many observation-based studies reported the formation and subsequent growth of particles in the atmosphere, both in polluted urban environments and in Asian continental outflow, where abundant precursor gases and pre-existing aerosols are prevalent (Kim et al., 2009, Kim et al., 2013, Kim et al., 2014, Lee et al., 2008, Song et al., 2010, Wang et al., 2014, Wu et al., 2007, Yum et al., 2007). Yum et al. (2007) reported that distinct NPF events occurred under cloud-free weather conditions induced by anticyclonic circulations positioned over northeast Asia. Song et al. (2010) reported that NPF events took place every five to six days in spring because of the periodic passage of a synoptic high pressure system. Lee et al. (2008) mentioned that most of the nucleation events were observed at the conditions of high ultraviolet-B (UV-B) irradiance and dry atmospheric conditions, or low relative humidity. Although these previous studies were concluded from single site observation, a very high probability of NPF occurring simultaneously in the Asian continental outflow region, including the Yellow Sea and the Korean Peninsula, was suggested based on the investigation of synoptic-scale meteorological conditions (e.g., Kim et al., 2009, Kim et al., 2013).

Simultaneous NPF events at multiple sites in the Asian continental outflow region and associated meteorological patterns have not been well investigated. This study focuses on investigating NPF events observed at four regional background stations in Korea in October 2012 and their characteristics, such as formation rate (FR), growth rate (GR), and condensation sink (CS). We elucidate the regional meteorological patterns on NPF events, including simultaneous NPF days observed at four stations, and non-NPF event days. An inter-site homogeneity in terms of the occurrence of NPF events and consistency in the temporal variability according to particle-size distribution is also presented.

Section snippets

Methodology

Aerosol number and size distributions were simultaneously measured by using a scanning mobility particle sizer (SMPS) at four regional background stations in the western coastal region of the Korean Peninsula during October 2012 (Fig. 1). Four sites are located in the major transport paths of aerosols and gas-phase precursors emitted from the Asian continent (Kim et al., 2007, Yoon et al., 2010). Fig. 1 shows the vertical column amount of boundary layer SO₂, averaged for October 2012, over East

Observations of NPF event in October 2012

Aerosol number-size distributions measured at four sites in October 2012 are shown in Fig. 2. Based on a sharp increase of particle number concentration in nucleation mode (so-called “banana shape”; Dal Maso et al., 2005), the formation and subsequent growth of freshly nucleated particles can be easily identified at all sites. Previous studies reported that the occurrence of NPF in October at both KGAWC and GCO was considerably higher than that in other months (Kim et al., 2013, Lee et al., 2008

Summary and conclusion

Number concentrations and size distributions of particles in the size range of 10–500 nm were simultaneously measured at four regional background stations in Korea during October 2012. NPF events were observed on 52% and 48% of measurement days, or 11 and 10 out of 21 days, at BCMO and KGAWC, respectively, and 43% measurement days, or 9 out of 21 days, at both GCO and JCMO. NPF event days at BCMO and KGAWC were similar, and those at GCO and JCMO were identical. NPFs were detected simultaneously at

Acknowledgments

This study was supported by the Korea Meteorological Administration Research and Development Program under the grant KMIPA2015-2011, the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science (2013R1A1A1006210), and project ‘Research on atmospheric brown clouds behavior around Korea Peninsula II’ (NIER-SP2014-290) funded by the National Institute Environmental Research. Yumi Kim was supported by the Korea Institute of Science and

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Characteristics of formation and growth of atmospheric nanoparticles observed at four regional background sites in Korea

Highlights

Abstract

Introduction

Section snippets

Methodology

Observations of NPF event in October 2012

Summary and conclusion

Acknowledgments

Atmos. Res.

Atmos. Res.

Atmos. Res.

Atmos. Environ.

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Atmos. Environ.

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J. Aerosol Sci.

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Atmos. Environ.

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J. Aerosol Sci.

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Atmos. Res.

Characterization of ultrafine particle number concentration and new particle formation in an urban environment of Taipei, Taiwan

Atmos. Chem. Phys.

Formation and growth of fresh atmospheric aerosols: eight years of aerosol size distribution data from SMEAR II, Hyytiälä, Finland

Boreal Environ. Res.

The ERA‐Interim reanalysis: configuration and performance of the data assimilation system

Q. J. R. Meteorol. Soc.

Nucleation and growth of new particles in Po Valley, Italy

Atmos. Chem. Phys.

Observations of new particle production in the atmosphere of a moderately polluted site in eastern England

J. Geophys. Res.

Observation of regional new particle formation in the urban atmosphere

Tellus