Statistical and Numerical Study to Construct Conceptual Model of Extratropical Cyclones around Japan

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K14391
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Meteorology/Physical oceanography/Hydrology
• Research Institution: The University of Tokyo
• Principal Investigator: Tochimoto Eigo 東京大学, 大気海洋研究所, 特任研究員 (40749917)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 温帯低気圧 / 前線

Outline of Final Research Achievements

Structures of extratropical cyclones(ECs) developing around Japan are examined statistically and those are compared with those developing over the Northwestern Atlantic (AO). ECs developing over the Sea of Japan and Okhotsk Sea are accompanied by strong cold fronts and relatively weak warm fronts, while ECs developing over Northwestern Pacific (PO) are accompanied by both strong warm and cold fronts. A comparison between AO and PO shows the differences in warm fronts. The warm fronts in the AO tend to extend northeastward, whereas those in the PO extend more southeastward. Composite analysis of their environments shows that the low-level baroclinicity in the AO extends northeastward to the east of the EC center, whereas that in the PO extends eastward, suggesting that the difference in the structure of the warm fronts between the AO and PO is caused by the structure of the environmental low-level temperature field.

Free Research Field

気象学

Academic Significance and Societal Importance of the Research Achievements

これまで、日本付近で発達する温帯低気圧構造の海域間の違いや北西大西洋の温帯低気圧との違いは十分に理解されておらず、本研究の成果によりこれらの違いを明確に示すことが出来た。また、海陸分布や水温分布の違いに起因する環境場の温度分布の違いが低気圧構造の違いをもたらしていることを示唆した。低気圧構造の違いを理解することは、それに伴う降水分布や風の分布の違いを理解することに繋がり、防災の観点から重要である。また、低気圧の構造を理解することで、より大規模な大気循環に対する影響の理解に貢献することが期待される。