TY - JOUR
T1 - Individual aerosol particles in and below clouds along a Mt. Fuji slope
T2 - Modification of sea-salt-containing particles by in-cloud processing
AU - Ueda, S.
AU - Hirose, Y.
AU - Miura, K.
AU - Okochi, H.
N1 - Funding Information:
We are indebted to S. Matsuyama and T. Isobe of the Faculty of Science and Engineering, Waseda University for the chemical analyses of gaseous materials. We gratefully acknowledge the NOAA Air Research Laboratory (ARL) for the provision of the HYSPLIT transport and dispersion model. This study was conducted during the period when the nonprofit organization ‘Valid Utilization of Mt. Fuji Weather Station’ had received a part of the Mt. Fuji Weather Station from the Japan Meteorological Agency and managed it. This study was partly supported by the Grants-in-Aid for Scientific Research, Category C (Grant No. 22510019 ), from JSPS .
PY - 2014/2
Y1 - 2014/2
N2 - Sizes and compositions of atmospheric aerosol particles can be altered by in-cloud processing by absorption/adsorption of gaseous and particulate materials and drying of aerosol particles that were formerly activated as cloud condensation nuclei. To elucidate differences of aerosol particles before and after in-cloud processing, aerosols were observed along a slope of Mt. Fuji, Japan (3776ma.s.l.) during the summer in 2011 and 2012 using a portable laser particle counter (LPC) and an aerosol sampler. Aerosol samples for analyses of elemental compositions were obtained using a cascade impactor at top-of-cloud, in-cloud, and below-cloud altitudes. To investigate composition changes via in-cloud processing, individual particles (0.5-2μm diameter) of samples from five cases (days) collected at different altitudes under similar backward air mass trajectory conditions were analyzed using a transmission electron microscope (TEM) equipped with an energy dispersive X-ray analyzer. For most cases (four cases), most particles at all altitudes mainly comprised sea salts: mainly Na with some S and/or Cl. Of those, in two cases, sea-salt-containing particles with Cl were found in below-cloud samples, although sea-salt-containing particles in top-of-cloud samples did not contain Cl. This result suggests that Cl in the sea salt was displaced by other cloud components. In the other two cases, sea-salt-containing particles on samples at all altitudes were without Cl. However, molar ratios of S to Na (S/Na) of the sea-salt-containing particles of top-of-cloud samples were higher than those of below-cloud samples, suggesting that sulfuric acid or sulfate was added to sea-salt-containing particles after complete displacement of Cl by absorption of SO2 or coagulation with sulfate. The additional volume of sulfuric acid in clouds for the two cases was estimated using the observed S/Na values of sea-salt-containing particles. The estimation revealed that size changes by in-cloud processing from below-cloud to top-of-cloud altitudes were less than 6% for sizes of 0.5-2μm diameter. The obtained results will be useful to evaluate the aging effect and transition of aerosol particles through in-cloud processing.
AB - Sizes and compositions of atmospheric aerosol particles can be altered by in-cloud processing by absorption/adsorption of gaseous and particulate materials and drying of aerosol particles that were formerly activated as cloud condensation nuclei. To elucidate differences of aerosol particles before and after in-cloud processing, aerosols were observed along a slope of Mt. Fuji, Japan (3776ma.s.l.) during the summer in 2011 and 2012 using a portable laser particle counter (LPC) and an aerosol sampler. Aerosol samples for analyses of elemental compositions were obtained using a cascade impactor at top-of-cloud, in-cloud, and below-cloud altitudes. To investigate composition changes via in-cloud processing, individual particles (0.5-2μm diameter) of samples from five cases (days) collected at different altitudes under similar backward air mass trajectory conditions were analyzed using a transmission electron microscope (TEM) equipped with an energy dispersive X-ray analyzer. For most cases (four cases), most particles at all altitudes mainly comprised sea salts: mainly Na with some S and/or Cl. Of those, in two cases, sea-salt-containing particles with Cl were found in below-cloud samples, although sea-salt-containing particles in top-of-cloud samples did not contain Cl. This result suggests that Cl in the sea salt was displaced by other cloud components. In the other two cases, sea-salt-containing particles on samples at all altitudes were without Cl. However, molar ratios of S to Na (S/Na) of the sea-salt-containing particles of top-of-cloud samples were higher than those of below-cloud samples, suggesting that sulfuric acid or sulfate was added to sea-salt-containing particles after complete displacement of Cl by absorption of SO2 or coagulation with sulfate. The additional volume of sulfuric acid in clouds for the two cases was estimated using the observed S/Na values of sea-salt-containing particles. The estimation revealed that size changes by in-cloud processing from below-cloud to top-of-cloud altitudes were less than 6% for sizes of 0.5-2μm diameter. The obtained results will be useful to evaluate the aging effect and transition of aerosol particles through in-cloud processing.
KW - Atmospheric aerosol particles
KW - Atmospheric aging
KW - Electron micrograph
KW - In-cloud process
KW - Mountain site
KW - Sea salt particle
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U2 - 10.1016/j.atmosres.2013.10.011
DO - 10.1016/j.atmosres.2013.10.011
M3 - Article
AN - SCOPUS:84887208824
SN - 0169-8095
VL - 137
SP - 216
EP - 227
JO - Atmospheric Research
JF - Atmospheric Research
ER -