2021 Fiscal Year Final Research Report
Exploring a new method for detecting slow new particle formation events relevant to the sustainment of background aerosols
| Project/Area Number |
20K21848
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| Research Category |
Grant-in-Aid for Challenging Research (Exploratory)
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| Allocation Type | Multi-year Fund |
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| Review Section |
Medium-sized Section 63:Environmental analyses and evaluation and related fields
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| Research Institution | Tokyo Metropolitan University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
飯田 健次郎 国立研究開発法人産業技術総合研究所, 計量標準総合センター, 主任研究員 (50540407)
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| Project Period (FY) |
2020-07-30 – 2022-03-31
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| Keywords | エアロゾル / 新粒子生成 / 核生成 / 雲凝結核 / 粒子帯電率 |
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| Outline of Final Research Achievements |
Aerosols can significantly affect the regional and global climate by acting as cloud condensation nuclei (CCN). New particle formation (NPF), which includes nucleation of molecular clusters and subsequent growth, could an important process affecting CCN number. Strong NPF events can be identified by the evolution of the aerosol number size distributions, whereas slow NPF events may not be clearly identified by those approaches. We propose a new method for detecting slow NPF events based on size-segregated particle number concentrations and the charged fraction of nanoparticles. We conducted field observations of aerosols in Tsukuba, Japan in the fall of 2021. We observed significant decreases in the charged fractions of nanoparticles (< 10 nm) in ambient air relative to those in the equilibrium conditions, which was associated with moderate increases in the particle number concentrations. These results suggest the occurrence of slow NPF originating from neutral molecular clusters.
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| Free Research Field |
大気化学
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| Academic Significance and Societal Importance of the Research Achievements |
新粒子生成がエアロゾル粒子数へ及ぼす影響を明らかにすることは、大気エアロゾルにおける根源的な課題であり、気候変動予測の不確実性低減につながるものである。従来の測定法・解析法では、粒子成長が広域でゆっくり進行する場合には新粒子生成とは認識されないが、広域エアロゾル粒子を維持する機構として鍵となる可能性がある。本研究において上記現象の検出法の初期開発に成功したことは、今後の研究につながる重要な成果である。
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