Development of a Novel Hydrometeor Classification Algorithm Using Dual-Polarization Radar and Its Application to the Detection of Precursors to Damaging Winds and Lightning

2023 Fiscal Year Final Research Report

• Project/Area Number: 19K23466
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0204:Astronomy, earth and planetary science, and related fields
• Research Institution: Japan, Meteorological Research Institute
• Principal Investigator: Umehara Akihito 気象庁気象研究所, 台風・災害気象研究部, 研究官 (10845944)
• Project Period (FY): 2019-08-30 – 2024-03-31
• Keywords: 二重偏波レーダー / 降水粒子判別 / 雷 / ダウンバースト / 竜巻

Outline of Final Research Achievements

We developed a novel hydrometeor classification algorithm using dual-polarization radar and applied this method to cases of lightning, a downburst, and tornadoes to investigate precursors. In lightning cases, we found that the lower positive charge, crucial for cloud-to-ground discharge, corresponded to liquid water-containing precipitation particles (LWP) above the 0°C level. In a downburst case, LWP aloft increased about 30 minutes prior, and hail aloft increased about 20 minutes prior to the event, with downburst occurring shortly after hail exceeded LWP. In tornado cases, we confirmed the detection of tornadic debris approximately 10 minutes before the tornado reached a damaged residential area. These findings show the potential of the developed method to detect precursors for lightning and damaging winds.

Free Research Field

レーダー気象学

Academic Significance and Societal Importance of the Research Achievements

本研究で開発した降水粒子判別手法により，積乱雲内部の微物理構造をより正確に捉えることができるようになった．また，この手法を用いることで，二重偏波レーダーから，発雷，突風の前兆を捉えられる可能性を示した．これらの成果は，雷や突風に関する直前予測情報の改善等に貢献し得る点で社会的意義が大きい．また，雷雲の電荷構造と対応する降水粒子特性を明らかにすることで，未だ明らかになっていない下層正電荷の電荷分離機構に新たな洞察を与えた点で，学術的意義も大きい．