Research activity information

• Mar. 2024 RIKEN, RIKEN Research Incentive Award (Ohbu Award)


• Mar. 2023 RIKEN, RIKEN Certificate of Application


• Feb. 2023 Japan Meteorological Society, Japan Meteorological Society SOLA Award, Observing System Simulation Experiment of a Rich Phased Array Wether Radar Network Covering Kyushu for July 2020 Heavy Rain Event


• Mar. 2005 九州大学大学院総合理工学府, 平成16年度修士論文 大気海洋環境システム学専攻賞

• A Planetary‐Scale Hydraulic Jump Driving Venus' Cloud Front

  Takeshi Imamura, Yasumitsu Maejima, Ko‐ichiro Sugiyama, Takehiko Satoh, Javier Peralta, Kevin McGouldrick, Takeshi Horinouchi, Kohei Ikeda

  Apr. 2026, Journal of Geophysical Research: Planets

  Scientific journal


• Dimensionality Reduction-based Interactive Visual Analytics Approach for Investigating EnsembleWeather Simulations

  Go Tamura, Sena Kobayashi, Naohisa Sakamoto, Yasumitsu Maejima, Jorji Nonaka

  2025, PROCEEDINGS OF INTERNATIONAL CONFERENCE ON HIGH PERFORMANCE COMPUTING IN ASIA-PACIFIC REGION, HPC ASIA 2025, 13 - 22, English

  International conference proceedings


• Forecast and Numerical Simulation Studies on Meso/Micro-scale High-Impact Weathers Using High-Performance Computing in Japan

  Kazuo Saito, Takuya Kawabata, Hiromu Seko, Takemasa Miyoshi, Le Duc, Tsutao Oizumi, Masaru Kunii, Guixing Chen, Kosuke Ito, Junshi Ito, Sho Yokota, Wataru Mashiko, Kenichiro Kobayashi, Shin Fukui, Eigo Tochimoto, Arata Amemiya, Yasumitsu Maejima, Takumi Honda, Hiroshi Niino, Masaki Satoh

  Springer International Publishing, Nov. 2023, Numerical Weather Prediction: East Asian Perspectives, 461 - 481

  In book


• Big Data Assimilation: Real-time 30-second-refresh Heavy Rain Forecast Using Fugaku During Tokyo Olympics and Paralympics

  Takemasa Miyoshi, Arata Amemiya, Shigenori Otsuka, Yasumitsu Maejima, James Taylor, Takumi Honda, Hirofumi Tomita, Seiya Nishizawa, Kenta Sueki, Tsuyoshi Yamaura, Yutaka Ishikawa, Shinsuke Satoh, Tomoo Ushio, Kana Koike, Atsuya Uno

  ACM, Nov. 2023, Proceedings of the International Conference for High Performance Computing, Networking, Storage and Analysis

  [Invited]

  International conference proceedings


• Dependency of the vertical propagation of mountain waves on the zonal wind and the static stability in the lower Venusian atmosphere

  Anna Suzuki, Hiroki Ando, Masahiro Takagi, Yasumitsu Maejima, Norihiko Sugimoto, Yoshihisa Matsuda

  Elsevier BV, May 2023, Icarus, 115615 - 115615, English

  [Refereed]

  Scientific journal


• Sensitivity to Localization Radii for an Ensemble Filter Numerical Weather Prediction System with 30-Second Update

  James Taylor, Takumi Honda, Arata Amemiya, Shigenori Otsuka, Yasumitsu Maejima, Takemasa Miyoshi

  Abstract A sensitivity analysis for horizontal localization scale is performed for a numerical weather prediction (NWP) system that uses a 30-second update to refresh a 500-m mesh with observations from a new-generation multi-parameter phased array weather radar (MP-PAWR). Testing is performed using three case studies of convective weather events that occurred during August/September 2019, with the aim to determine the most suitable scale for short-range forecasting of precipitating convective systems and better understand model behavior to a rapid update cycle. Results showed that while the model could provide useful skill at lead times up to 30-minutes, forecasts would consistently over-estimate rainfall and were unable to outperform nowcasts performed with a simple advection model. Using a larger localization scale e.g., 4-km, generated stronger convective and dynamical instability in the analyzes that made conditions more favorable for spurious and intense convection to develop in forecasts. It was demonstrated that lowering the localization scale reduced the size of analysis increments during early cycling, limiting the buildup of these conditions. Improved representation of the localized convection in the initial conditions was suggested as an important step to mitigating this issue in the model.

  American Meteorological Society, Jan. 2023, Weather and Forecasting

  [Refereed]

  Scientific journal


• Advantage of 30‐s‐Updating Numerical Weather Prediction With a Phased‐Array Weather Radar Over Operational Nowcast for a Convective Precipitation System

  T. Honda, A. Amemiya, S. Otsuka, J. Taylor, Y. Maejima, S. Nishizawa, T. Yamaura, K. Sueki, H. Tomita, T. Miyoshi

  American Geophysical Union ({AGU}), Jun. 2022, Geophysical Research Letters, 49(11) (11), English

  [Refereed]

  Scientific journal


• Development of the Real‐Time 30‐s‐Update Big Data Assimilation System for Convective Rainfall Prediction with a Phased Array Weather Radar: Description and Preliminary Evaluation

  T. Honda, A. Amemiya, S. Otsuka, G.-Y. Lien, J. Taylor, Y. Maejima, S. Nishizawa, T. Yamaura, K. Sueki, H. Tomita, S. Satoh, Y. Ishikawa, T. Miyoshi

  American Geophysical Union ({AGU}), May 2022, Journal of Advances in Modeling Earth Systems, English

  [Refereed]

  Scientific journal


• Angular-based Edge Bundled Parallel Coordinates Plot for the Visual Analysis of Large Ensemble Simulation Data.

  Keita Watanabe, Naohisa Sakamoto, Jorji Nonaka, Yasumitsu Maejima

  With the continuous increase in the computational power and resources of modern high-performance computing (HPC) systems, large-scale ensemble simulations have become widely used in various fields of science and engineering, and especially in meteorological and climate science. It is widely known that the simulation outputs are large time-varying, multivariate, and multivalued datasets which pose a particular challenge to the visualization and analysis tasks. In this work, we focused on the widely used Parallel Coordinates Plot (PCP) to analyze the interrelations between different parameters, such as variables, among the members. However, PCP may suffer from visual cluttering and drawing performance with the increase on the data size to be analyzed, that is, the number of polylines. To overcome this problem, we present an extension to the PCP by adding B\'{e}zier curves connecting the angular distribution plots representing the mean and variance of the inclination of the line segments between parallel axes. The proposed Angular-based Parallel Coordinates Plot (APCP) is capable of presenting a simplified overview of the entire ensemble data set while maintaining the correlation information between the adjacent variables. To verify its effectiveness, we developed a visual analytics prototype system and evaluated by using a meteorological ensemble simulation output from the supercomputer Fugaku.

  2022, The 12th IEEE Symposium on Large Data Analysis and Visualization (LDAV2022), abs/2209.10874, 43 - 52, English

  [Refereed]


• Angular-based Edge Bundled Parallel Coordinates Plot for the Visual Analysis of Large Ensemble Simulation Data.

  Keita Watanabe, Naohisa Sakamoto, Jorji Nonaka, Yasumitsu Maejima

  IEEE, 2022, 12th IEEE Symposium on Large Data Analysis and Visualization(LDAV), 1 - 10

  International conference proceedings


• Predictability of the July 2020 Heavy Rainfall with the SCALE-LETKF

  James Taylor, Arata Amemiya, Takumi Honda, Yasumitsu Maejima, Takemasa Miyoshi

  2021, SOLA, English, Domestic magazine

  [Refereed]

  Scientific journal


• Impact of the Window Length of Four-Dimensional Local Ensemble Transform Kalman Filter: A Case of Convective Rain Event

  Yasumitsu Maejima, Takemasa Miyoshi

  Lead, Meteorological Society of Japan, 2020, SOLA, 16(0) (0), 37 - 42

  [Refereed]

  Scientific journal


• Impact of Dense and Frequent Surface Observations on 1-Minute-Update Severe Rainstorm Prediction: A Simulation Study

  Yasumitsu MAEJIMA, Takemasa MIYOSHI, Masaru KUNII, Hiromu SEKO, Kae SATO

  Lead, Meteorological Society of Japan, 2019, Journal of the Meteorological Society of Japan. Ser. II, 97(1) (1), 253 - 273

  [Refereed]

  Scientific journal


• Assimilation of Himawari-8 All-Sky Radiances Every 10 Minutes: Impact on Precipitation and Flood Risk Prediction

  T. Honda, S. Kotsuki, G. Y. Lien, Y. Maejima, K. Okamoto, T. Miyoshi

  Blackwell Publishing Ltd, Jan. 2018, Journal of Geophysical Research: Atmospheres, 123(2) (2), 965 - 976, English

  [Refereed]

  Scientific journal


• A visual causal exploration framework case study: a torrential rain and a flash flood in Kobe city.

  Jorji Nonaka, Naohisa Sakamoto, Yasumitsu Maejima, Kenji Ono, Koji Koyamada

  ACM, 2017, SIGGRAPH Asia 2017 Symposium on Visualization, SA 2017, 8 - 8

  [Refereed]

  International conference proceedings


• 30-second-Update 100-m-Mesh Data Assimilation Experiments: A Sudden Local Rain Case in Kobe on 11 September 2014

  Maejima Yasumitsu, Kunii Masaru, Miyoshi Takemasa

  2017, SOLA, 13, 174 - 180, English

  [Refereed]


• "Big Data Assimilation" Toward Post-Petascale Severe Weather Prediction: An Overview and Progress

  Miyoshi Takemasa, Lien Guo-Yuan, Satoh Shinsuke, Ushio Tomoo, Bessho Kotaro, Tomita Hirofumi, Nishizawa Seiya, Yoshida Ryuji, Adachi Sachiho A, Liao Jianwei, Gerofi Balazs, Ishikawa Yutaka, Kunii Masaru, Ruiz Juan, Maejima Yasumitsu, Otsuka Shigenori, Otsuka Michiko, Okamoto Kozo, Seko Hiromu

  Nov. 2016, PROCEEDINGS OF THE IEEE, 104(11) (11), 2155 - 2179, English

  [Refereed]

  Scientific journal


• Convective generation and vertical propagation of fast gravity waves on Mars: One- and two-dimensional modeling

  Takeshi Imamura, Ayuka Watanabe, Yasumitsu Maejima

  Academic Press Inc., Mar. 2016, Icarus, 267, 51 - 63, English

  [Refereed]

  Scientific journal


• Inverse insolation dependence of Venus' cloud-level convection

  Takeshi Imamura, Takehito Higuchi, Yasumitsu Maejima, Masahiro Takagi, Norihiko Sugimoto, Kohei Ikeda, Hiroki Ando

  Elsevier BV, Jan. 2014, Icarus, 228, 181 - 188, English

  [Refereed]

  Scientific journal


• The Time Evolution of Meso-scale Disturbances in the Atmosphere Caused by Frontal Instability

  Yasumitsu MAEJIMA, Keita IGA

  Lead, Dec. 2011, Theoretical and Applied Mechanics Japan, 60, 183 - 191

  [Refereed]


• Upper-tropospheric vortex street and its formation mechanism

  Yasumitsu Maejima, Keita Iga, Hiroshi Niino

  Lead, Meteorological Society of Japan, 2006, Scientific Online Letters on the Atmosphere, 2, 80 - 83, English

  [Refereed]

  Scientific journal

• 局地的豪雨の予測における稠密な地上観測データ同化の効果

  前島康光, 国井勝, 瀬古弘, 前田亮太, 佐藤香枝, 三好建正

  30 Apr. 2015, 日本気象学会大会講演予稿集, (107) (107), 382, Japanese


• D152 ビッグデータ同化システムを用いた局地的豪雨発生過程のシミュレーション(気象予報・データ同化,一般口頭発表)

  前島 康光, 国井 勝, 瀬古 弘, 呉 宏堯, 佐藤 香枝, 三好 建正

  日本気象学会, 2015, 大会講演予講集, 108, 162 - 162, Japanese


• D156 2008年7月28日に神戸市付近で発生した局地的大雨の観測システムシミュレーション実験(ハイパフォーマンスコンピューティングによる超高精度メソスケール気象予測,スペシャル・セッション)

  前島 康光, 国井 勝, 瀬古 弘, 前田 亮太, 佐藤 香絵, 三好 建正

  日本気象学会, 2014, 大会講演予講集, 106, 169 - 169, Japanese

• Circulation of Venus atmosphere from the surface to the upper atmosphere driven by waves and convection

  今村 剛, 三好 建正, 高木 征弘, 杉本 憲彦, 榎本 剛, 堀之内 武, はしもと じょーじ, 佐川 英夫, 樫村 博基, 石渡 正樹, 前島 康光

  Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (S), The University of Tokyo, 01 Apr. 2024 - 31 Mar. 2029


• 「ゲリラ豪雨」予報高精度化に向けた超高頻度・高解像度雷発光データ同化

  前島 康光

  日本学術振興会, 科学研究費助成事業, 若手研究, 国立研究開発法人理化学研究所, Apr. 2018 - Mar. 2023

  令和3年度は、雷発光データ同化を行うために必要な観測演算子の改良、実際にゲリラ豪雨を対象としたデータ同化実験、の2点を到達目標に設定し研究を行ってきた。令和2年度までに観測演算子の開発を一通り終えていたが、予報精度の向上を目的に、さらなる改良に取り組んだ。令和2年度の後半から取り組んできた、機械学習にて雷発光データと氷晶の質量との関係性を見出す研究を推進した。令和2年度に氷晶の質量が乾燥大気1㎏あたり0.1gの時に、雷発光が最も進発していることを突き止めたが、今年度は、氷晶の中でも、粒子の直径が1mm以上のあられと、それ未満の雲氷に分け、それぞれに対して雷発光頻度との高い相関関係につながるパラメータレンジを絞り込んだ。 さらに、改良した観測演算子を、数値気象予報システムSCALE-LETKFに実装し、2015年8月11日午前0時～2時にかけて神戸、大阪付近で発生したゲリラ豪雨事例に対して、雷発光データ同化実験を行った。雷発光データ同化を行わなかった場合は、降水量がピーク値で比較して観測値の48％にとどまっていたが、同化を行うことでこれを66％にまで改善することが確かめられた。特に、雷発光頻度が高い領域において、降水強度予測の改善が大きく、ピークの降水強度改善に貢献した。ゲリラ豪雨における気象災害は、通常降水量が多い領域で起きるため、ピークの降水量の予報精度向上が防災・減災の観点から重要となる。その意味で、雷発光データ同化によってピークの降水量予報改善の可能性を示すことができたことは、本課題の実績として大きい。改善一方、雷発光頻度が30秒で20回以下の場合、同化によってかえって降水強度の予測精度が悪化した領域も見られた。これらの結果は、2022年度に行われる国内外の学会で講演を行い、さらに論文化することで本課題の確たる業績とする。


• 冬季日本側に突風災害をもたらす擾乱の発生環境場の解明

  前島 康光

  日本学術振興会, 科学研究費助成事業, 若手研究(B), 名古屋大学, Apr. 2012 - Mar. 2013

• NHK World Japan Science View

  NHK, Mar. 2024

  Media report


• Sankei News Paper Column

  Sankei Shimbun Co., Ltd.

  Paper