Turbulence accompanied by wind gusts and heavy precipitation in sever weather phenomena

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K03967
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 17020:Atmospheric and hydrospheric sciences-related
• Research Institution: Tohoku University (2020-2022); The University of Tokyo (2019)
• Principal Investigator: Ito Junshi 東北大学, 理学研究科, 准教授 (00726193)
• Co-Investigator(Kenkyū-buntansha): 毛利 英明 気象庁気象研究所, 気象予報研究部, 室長 (10354490) ; 新野 宏 東京大学, 大気海洋研究所, 名誉教授 (90272525)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 極端気象 / LES / 気象モデル / 線状降水帯 / 台風 / 竜巻 / 接地境界層 / 乱流

Outline of Final Research Achievements

We performed and analyzed Large Eddy Simulations (LES) of a variety of extreme weather events.
1) We presented idealized experiments of heavy rainfall by quasi-stationary quasi-linear convective system (back-building system) and conducted sensitivity experiments for various soundings using this setup. 2) We analyzed simulation results of tornadoes that occurred near Nobeoka in the Typhoon 1917. 3) We conducted LES for the entire tropical cyclone from onset to rapid development and matured stage.
Based on wind tunnel experiments and field observations, a new parameterization of surface layer fluxes suitable for the LES has been developed.

Free Research Field

気象学

Academic Significance and Societal Importance of the Research Achievements

極端気象に伴う乱流は水平非一様、かつ自由大気中も活発であり、通常時の乱流とは異なる。極端現象時の気流構造や温度構造を３次元的に把握できるLESとよばれる高解像度・大規模シミュレーションにより、線状降水帯・台風・竜巻などの極端気象を捉えた。この計算結果を活用し、乱流のメカニズムなどの実態・役割の解明や、適切なパラメタライズ手法を探った。観測や実験データを用い、このようなシミュレーションの検証や高精度化も行った。