Structure and Dynamics of Cyclones that Cause Tornadoes and Severe Gusty Winds

2017 Fiscal Year Final Research Report

• Project/Area Number: 24244074
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Meteorology/Physical oceanography/Hydrology
• Research Institution: The University of Tokyo
• Principal Investigator: Niino Hiroshi 東京大学, 大気海洋研究所, 客員教授 (90272525)
• Co-Investigator(Kenkyū-buntansha): 柳瀬 亘 東京大学, 大気海洋研究所, 助教 (80376540)
• Co-Investigator(Renkei-kenkyūsha): 伊賀 啓太 東京大学, 大気海洋研究所, 准教授 (60292059)
• Research Collaborator: 栃本 英伍 東京大学, 大気海洋研究所, 特任研究員
• Project Period (FY): 2012-04-01 – 2017-03-31
• Keywords: 竜巻 / スーパーセル / 温帯低気圧 / 熱帯低気圧 / 積乱雲 / 対流有効位置エネルギー / ヘリシティ / 温帯低気圧化

Outline of Final Research Achievements

Structure and environment of tornado-spawning tropical and extratropical cyclones are clarified, and convective available potential energy that incorporates effects of entrainment of the environmental air is shown to be useful for estimating tornado potential in a tropical cyclone. Assimilation of data of dense surface observational network and Doppler radars, using nested local ensemble transform Kalman filter, is shown to improve the prediction of the path of the low-level mesocyclone associated with the tornado-spawning supercell. The predicted strength of the tornado is well correlated with the vertical vorticity of the LMC and low-level relative humidity in the supercell, so that a probability map of encounter with LMC based on an ensemble prediction is promising for predicting tornado risk. Furthermore, an ultra-high resolution simulation succeeded in reproducing the observed multiple-vortex structure of Tsukuba, Ibaraki tornado on 6 May 2012.

Free Research Field

気象学