Prediction of Future Changes in the Mechanism of Heavy Rainfall in the Baiu Season by a Pseudo Global Warming Method Using Observational data

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K20449
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0303:Civil engineering, social systems engineering, safety engineering, disaster prevention engineering, and related fields
• Research Institution: Kyoto University
• Principal Investigator: Naka Yukari 京都大学, 防災研究所, 助教 (30909445)
• Project Period (FY): 2021-08-30 – 2024-03-31
• Keywords: 梅雨前線 / 線状対流系豪雨 / 地球温暖化 / 擬似温暖化実験 / 発生メカニズム

Outline of Final Research Achievements

We conducted a pseudo global warming experiment for a past heavy rainfall during Baiu season (line-shaped convective system) and found that the Bulk-Richardson number, an index representing the ratio of buoyancy to turbulence, was constant in all past and future experiments.
Based on this finding, in addition to future projections, we analyzed past events of line-shaped convection systems using Radar-AMeDAS rainfall data. The results of the analysis of the atmospheric environment of past line-shaped convection systems classified into (A) systems generated by large-scale convergence by fronts and (B) localized systems generated in isolation from fronts indicate that the bulk Richardson number is more important for (B) localized and self-organized systems.

Free Research Field

水文気象気候工学

Academic Significance and Societal Importance of the Research Achievements

本研究は，近年学術的にも社会的にも注目されている，梅雨前線に伴う線状対流系豪雨に着目し，そのメカニズム解明及び将来予測に取り組んだ研究である．特に本研究は，従来行われていたような気候予測情報を用いて将来予測を行うというだけでなく，過去に発生した事例の理解に基づきメカニズムそのものの将来予測を行うという点で独自性が高く，気象学・気候学・工学全てに対して本研究が持つ学術的意義は大きいものである．本研究課題で十分に解明できなかった課題についても，今後引き続き研究を進めていく予定である．