Black carbon and iron oxide aerosols in Arctic Snowpack, based on advanced techniques

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K20441
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 63010:Environmental dynamic analysis-related
• Research Institution: Tokyo University of Science
• Principal Investigator: Mori Tatsuhiro 東京理科大学, 理学部第一部物理学科, 助教 (60801181)
• Project Period (FY): 2019-04-01 – 2021-03-31
• Keywords: 北極 / 黒色炭素粒子 / 黒色酸化鉄粒子 / レーザー誘起白熱法 / 粒径別質量濃度 / 沈着量 / 広域分布

Outline of Final Research Achievements

Black carbon (BC) and iron oxide (FeOx) aerosols deposited on snow lowers its albedo, potentially contributing to warming in the Arctic. Atmospheric distributions of BC and FeOx, which contribute directly and indirectly to radiative forcing, are also greatly influenced by depositions. To quantify these effects, we developed an improved technique for measuring the size distributions of BC and FeOx aerosols in liquid water and made an accurate measurement of the spatial distributions of BC and FeOx in snowpack in Arctic regions. Our measurements revealed that BC mass concentrations in the snowpack were lower by a factor of ~ 13 than previous measurements. The average size distributions of BC in Arctic snowpack shifted to smaller sizes with decreasing BC concentration in snowpack due to an increase in the removal efficiency of larger BC particles during transport from lower latitudes.

Free Research Field

大気環境科学

Academic Significance and Societal Importance of the Research Achievements

北極広域に沈着したBCやFeOx粒子の質量濃度、粒径、沈着量の高精度な測定データは、北極圏の気候を予測するモデルの検証に非常に有効である。特に、積雪中BC質量濃度の測定技術の確立により、従来法ではBC濃度が10倍程度も過大評価し、雪面反射率の予測値にも波及的に不確実性を含む可能性を明らかにした。この結果は、次回の北極評議会の作業部会の報告書でも重要な知見として取り上げられる見込みである。本研究成果は今後の北極圏の気候変動への理解に貢献するだけでなく、適切な社会政策を行う上でも重要な知見となりうる。