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Elucidation of the mechanism of "warm rain" in urban atmosphere and optimization of numerical forecast models

Research Project

Project/Area Number 21H01163
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Review Section Basic Section 17020:Atmospheric and hydrospheric sciences-related
Research InstitutionNihon University (2022-2023)
National Research Institute for Earth Science and Disaster Prevention (2021)

Principal Investigator

MISUMI Ryohei  日本大学, 文理学部, 教授 (20414401)

Co-Investigator(Kenkyū-buntansha) 橋本 明弘  気象庁気象研究所, 気象予報研究部, 室長 (20462525)
Project Period (FY) 2021-04-01 – 2024-03-31
Project Status Completed (Fiscal Year 2023)
Budget Amount *help
¥17,940,000 (Direct Cost: ¥13,800,000、Indirect Cost: ¥4,140,000)
Fiscal Year 2023: ¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000)
Fiscal Year 2022: ¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000)
Fiscal Year 2021: ¥12,220,000 (Direct Cost: ¥9,400,000、Indirect Cost: ¥2,820,000)
Keywords降水システム / 雲物理 / 暖かい雨 / 雲粒 / 降水 / 数値予報 / エアロゾル・雲相互作用 / 降水過程
Outline of Research at the Start

雨が降るメカニズムには「暖かい雨」と「冷たい雨」とがある。前者は雲粒が互いに併合して雨滴へと成長するものであり、後者は氷粒子が昇華成長し融解して雨滴となるものである。
東京のような大都市では、凝結核が豊富にあるため、粒径の小さな雲粒が多数形成されやすく、「暖かい雨」は起こりにくいと考えられてきた。ところが近年、東京周辺でも暖かい雨が報告されるようになってきた。
そのメカニズムを解明し、降水予報精度を向上させるため、東京スカイツリーを利用した雲粒・雨滴の詳細な観測を行うとともに、得られた結果を数値予報モデルに反映させ、数値予報の向上を図る。

Outline of Final Research Achievements

It has been believed that precipitation through the warm rain process is less likely to occur in urban areas due to the abundance of aerosol particles. However, warm rain is often observed in Tokyo. The warm rain process in Tokyo was investigated through observations using Ka-band radar, a cloud droplet spectrometer, and numerical simulations. The results showed that large droplets formed through condensation process, and the droplets grew through collision coalescence with other particles. This process could occur when the cloud droplet number concentration was less than 1200 cm-3. An introduction of observation-based cloud droplet size distributions into the JMA nonhydrostatic model had a significant impact on the forecasting of warm stratiform rainfall through the increase of auto-conversion rate from cloud water to rain.

Academic Significance and Societal Importance of the Research Achievements

東京上空におけるエアロゾル、雲凝結核、雲粒の数濃度のデータが学術論文を通して公表され、気象モデルの基礎となるデータが提供された。また、東京で起こる「暖かい雨」のメカニズムが明らかになり、この成果を通して「雨滴がどのようにして形成されるのか」について概念モデルが構築された。さらに雲粒粒径分布の仮定が、暖かい層状性降水の予報に影響を及ぼすことが分かり、数値予報モデルの高度化の方向性が示された。

Report

(4 results)
  • 2023 Annual Research Report   Final Research Report ( PDF )
  • 2022 Annual Research Report
  • 2021 Annual Research Report
  • Research Products

    (9 results)

All 2024 2023 2022 2021

All Journal Article (5 results) (of which Peer Reviewed: 4 results,  Open Access: 3 results) Presentation (4 results) (of which Invited: 1 results)

  • [Journal Article] Microphysical Characteristics of Warm Convective Precipitation in Tokyo2024

    • Author(s)
      Misumi Ryohei、Uji Yasushi、Maesaka Takeshi
    • Journal Title

      SOLA

      Volume: 20 Issue: 0 Pages: 8-15

    • DOI

      10.2151/sola.2024-002

    • ISSN
      1349-6476
    • Related Report
      2023 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Structure of shallow squall line-like precipitation system observed in Kanto Region, Japan, using Ka-band and X-band radars2024

    • Author(s)
      Matsuoka Yuta、Misumi Ryohei、Maesaka Takeshi
    • Journal Title

      Atmospheric Research

      Volume: 未定 Pages: 107350-107350

    • DOI

      10.1016/j.atmosres.2024.107350

    • Related Report
      2023 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Numerical simulations of a warm rain event observed in Tokyo, Japan2023

    • Author(s)
      Hashimoto Akihiro, Misumi Ryohei
    • Journal Title

      Research Activities in Atmospheric and Earth System Modelling/WMO

      Volume: 53

    • Related Report
      2023 Annual Research Report
  • [Journal Article] Studies on Aerosols and Clouds Using Tokyo Skytree2022

    • Author(s)
      三隅 良平,岩本 洋子,當房 豊,森 樹大,三浦 和彦
    • Journal Title

      Earozoru Kenkyu

      Volume: 37 Issue: 2 Pages: 96-103

    • DOI

      10.11203/jar.37.96

    • ISSN
      0912-2834, 1881-543X
    • Year and Date
      2022-06-20
    • Related Report
      2022 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Classification of aerosol-cloud interaction regimes over Tokyo2022

    • Author(s)
      Misumi Ryohei、Uji Yasushi、Miura Kazuhiko、Mori Tatsuhiro、Tobo Yutaka、Iwamoto Yoko
    • Journal Title

      Atmospheric Research

      Volume: 272 Pages: 106150-106150

    • DOI

      10.1016/j.atmosres.2022.106150

    • Related Report
      2021 Annual Research Report
    • Peer Reviewed / Open Access
  • [Presentation] 都市大気で起こる暖かい雨 ー東京都心部における事例解析ー2023

    • Author(s)
      三隅良平, 宇治靖, 前坂剛
    • Organizer
      日本気象学会2023年度春季大会
    • Related Report
      2023 Annual Research Report
  • [Presentation] 令和元年東日本台風に伴う豪雨のメカニズムについて2023

    • Author(s)
      三隅良平
    • Organizer
      日本地球惑星科学連合2023年大会 [U-11] 気圏・水圏・地圏にまたがる複合災害
    • Related Report
      2023 Annual Research Report
    • Invited
  • [Presentation] 都市大気で起こる暖かい雨 ―東京都心部における事例解析―2023

    • Author(s)
      三隅良平
    • Organizer
      2022年度エアロゾル・雲・降水の相互作用に関する研究集会
    • Related Report
      2022 Annual Research Report
  • [Presentation] 東京におけるエアロゾル・雲相互作用のレジーム分類2021

    • Author(s)
      三隅良平 , 宇治靖 , 當房豊 , 三浦和彦 , 森樹大 , 岩本洋子
    • Organizer
      日本気象学会2021年度秋季大会
    • Related Report
      2021 Annual Research Report

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Published: 2021-04-28   Modified: 2025-01-30  

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