Clarifying the cause of the early twentieth century Arctic warming

2017 Fiscal Year Final Research Report

• Project/Area Number: 16K17802
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Meteorology/Physical oceanography/Hydrology
• Research Institution: Kyoto University
• Principal Investigator: Tokinaga Hiroki 京都大学, 白眉センター, 特定准教授 (80421890)
• Research Collaborator: XIE Shang-Ping カルフォルニア大学サンディエゴ校, スクリップス海洋研究所, 教授
• Project Period (FY): 2016-04-01 – 2018-03-31
• Keywords: 北極温暖化 / 太平洋数十年規模振動 / 大西洋数十年規模振動 / 大気海洋相互作用

Outline of Final Research Achievements

The purpose of this study is to clarify a mechanism for the early 20th century Arctic warming. We have performed (1) a statistical analysis with historical ocean-atmosphere observations, (2) numerical experiments with an atmospheric general circulation model, and (3) statistical analysis with CMIP5 pre-industrial control simulations. We found that both the Aleutian low and surface westerly winds over the Northern Eurasia intensify due to simultaneous negative-to-positive shifts of the Pacific and Atlantic multidecadal oscillations. These changes in atmospheric circulation enhance the warm advection over the high latitude regions, leading to the entire warming over the Arctic.

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