Estimation of Physical Upper Bound of Precipitation Caused by Weather Front in Japan

2021 Fiscal Year Final Research Report

• Project/Area Number: 19H02251
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 22040:Hydroengineering-related
• Research Institution: Kumamoto University
• Principal Investigator: ISHIDA KEI 熊本大学, くまもと水循環・減災研究教育センター, 准教授 (70800697)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 想定最大規模降水量 / 領域大気モデル / 力学的ダウンスケーリング / 前線性降雨

Outline of Final Research Achievements

An approach to estimate the physical upper bound of precipitation by means of a regional atmospheric model was previously developed in the United States in order to overcome weaknesses of the traditional approaches. This research study investigated the applicability of the proposed approach to frontal precipitation in Japan. The target area is the Asakura area where there was a severe precipitation in the past. First, precipitation events were extracted. Second, parameterization schemes of the regional atmospheric model were optimized. Then, the precipitation depth at each event was maximized by means of numerical experiments. Finally, the largest value of the maximized precipitation depths was selected as the physical upper bound of the precipitation at the target area. In addition, the causes of severe precipitation were investigated.

Free Research Field

水工学

Academic Significance and Societal Importance of the Research Achievements

本研究により領域大気モデルを用いたMP Estimation法による想定最大規模降水量の推定が日本における前線性降雨にも有効であることが示された．さらには，本手法で得られたデータを用いた物理的考察により対象地において豪雨が発生しやすい大気状況の推定も可能であることが分かった．これらは日本においても水利構造物等やハザードマップ作製等に対してより信頼性のある想定最大規模降水量を提供できる可能性を示しており，本研究は今後の防災・減災において有用な知見を与えるものと考えられる．