About me

Welcome to Kota Takeda’s home page! Japanese page »

Assistant Professor, Department of Applied Physics, Graduate School of Engineering, Nagoya University
takeda[at]na.nuap.nagoya-u.ac.jp

Visiting Researcher, Data Assimilation research team, RIKEN Center for Computational Science

Research Interests

My research focuses on applying mathematical tools to analyze complex and chaotic phenomena, utilizing both theoretical and numerical methods. In particular, I’m working on UQ(Uncertainty Quantification) approaches to mathematical fluid mechanics.

I am also interested in interdisciplinary studies, where I would like to interact with many researchers in different fields by using mathematics.

Ph.D Thesis

Error Analysis of the Ensemble Square Root Filter for Dissipative Dynamical Systems

Specific themes

Mathematical analysis of data assimilation
Building the fundamental framework of data assimilation with topological data
Computing a stationary flow of the 2D Euler equation with Hamiltonian Monte Carlo

Keywords

Uncertainty Quantification(UQ), mathematical fluid mechanics, Topological Flow Data Analysis(TFDA), data assimilation, interdisciplinary studies, machine learning, weather forecasting

C.V.

Education

Mar. 2025	Doctor of Science from Graduate School of Science, Kyoto University. Thesis：Error Analysis of the Ensemble Square Root Filter for Dissipative Dynamical Systems Supervisor: Professor Takashi Sakajo (Kyoto University), Professor Takemasa Miyoshi (Kyoto University & RIKEN), Professor Sebastian Reich (University of Potsdam)
Mar. 2022	Master of Science from Graduate School of Science, Kyoto University. Supervisor: Professor Takashi Sakajo (Kyoto University)
Mar. 2020	Bachelor of Science from Faculty of Science, Kyoto University. Supervisor: Professor Takashi Sakajo (Kyoto University)

Employment

Jul. 2025 - Visiting Researcher, Data Assimilation research team, RIKEN Center for Computational Science
Apr. 2025 - Assistant Professor, Department of Applied Physics, Graduate School of Engineering, Nagoya University
Apr. 2022 - Mar. 2025 Kyoto University Graduate Division Fellow Kyoto University Division of Graduate Studies
Apr. 2022 - Mar. 2025 RIKEN Junior Research Associate at R-CCS Data Assimilation research team JRA 2022

Funds

2025 (-2028)	2025 RIKEN Special Postdoctoral Researcher (SPDR), awarded but declined
2025 (-2028)	2025 JSPS Postdoctoral Fellowship (PD), awarded but declined
2024	A novel approach to ensemble data assimilation based on the instability of chaotic dynamical systems The 63rd Leave a Nest incu-be award from Leave a Nest Co., Ltd.
2022 - 2025	Comprehensive application of uncertainty quantification to mathematical fluid mechanics - with a focus on vortex dynamics and data assimilation　 Support for Pioneering Research Initiated by the Next Generation program operated by the Japan Science and Technology Agency（2022）
2022 - 2025	Constructing topological data assimilation theory 2022 RIKEN Junior Research Associate Program, Mathematical Science （RIKEN R-CCS Data assimilation research team）

Awards

2025	The 42nd Inoue Research Award for Young Scientists, Inoue Zaidan
2025	Certificate of Recognition, Student Chapters, Society for Industrial and Applied Mathematics
2025	R-CCS Award: Best Presentation Award for Young Researcher / The 20th International Conference on Flow Dynamics
2025	The MSJ Prize for Excellent Young Applied Mathematicians 2024, The Mathematical Society of Japan
2024	The 63rd Leave a Nest incu-be award from Leave a Nest Co., Ltd.
2023	The 20th International Conference on Flow Dynamics Best Presentation Award for Young Researcher
2023	Poster Award Mathematical Science Prize at RIKEN summer school 2023

Visit

Feb.-Mar., Sep.-Oct. 2024	The University of Potsdam, Germany (host: Prof. Sebastian Reich).
Mar. 2024	IMT Atlantique, France (host: Prof. Pierre Tandeo).

Publications

2026	Observed–unobserved information transfer in ensemble Kalman filtering for the partially observed Lorenz 96 model K. Takeda, Nonlinear Science, 9, 100220. DOI arXiv
2026	Noise-scaled accuracy of the ensemble Kalman filter with an instability-based minimum ensemble size K. Takeda and T. Miyoshi, Nonlinear Processes in Geophysics 33, 335–346. DOI Binder Code
2024	Uniform Error Bounds of the Ensemble Transform Kalman Filter for Chaotic Dynamics with Multiplicative Covariance Inflation K. Takeda and T. Sakajo, SIAM/ASA Journal on Uncertainty Quantification, 12(4), 1315–1335. DOI Manuscript Code
2024	Topological regularization on numerical simulations of the advection equation K. Takeda, S. Kaji, and T. Miyoshi, JSIAM Letters, 16, 53–56. DOI
2023	Geometric Ergodicity for Hamiltonian Monte Carlo on Compact Manifolds K. Takeda and T. Sakajo, SIAM Journal on Numerical Analysis, 61(6), 2994-3013. DOI

Preprints

2026	A Second-Order Asymptotic Expansion for Nonlinear Filtering in the Lorenz–63 System M. Kurisaki and K. Takeda, arXiv preprint, arXiv:2610.12512. arXiv

Presentations

2026/12/4-5 (upcoming)	oral Invited	Topology and Data: Theory, Machine Learning and Applications, “TBD”, KIAS, Korea, 12/4-12/5.
2026/11/27 (upcoming)	oral Invited	2nd Workshop on Learning Dynamical System (WLDS2), “Ensemble Data Assimilation in High-Dimensional Chaotic Systems: Exploiting Low-Dimensional Structures”, RIKEN AIP, Tokyo, Japan, 2026/11/25-27.
2026/9/14	oral Invited	ICMASE 2026, “Ensemble Data Assimilation in High-Dimensional Chaotic Systems: Exploiting Low-Dimensional Structures”, Nagoya University, Japan, 2026/9/14-17.
2026/7/8	oral Invited	International Workshop on Numerical Analysis and Applications, “Error analysis on data assimilation for chaotic dynamical systems”, Northwest Normal University, China, 2026/7/7-10.
2026/3/24	oral	SIAM Conference on Uncertainty Quantification (UQ26), “Error Analysis of the Projected Po Method with Additive Inflation for the Partially Observed Lorenz 96 Model”, Minneapolis, Minnesota, U.S., 3/22-25.
2025/11/28	oral Invited	2025 KSIAM Annual Meeting, “Ensemble Data Assimilation in High-Dimensional Chaotic Systems: Exploiting Low-Dimensional Structures”, Gyeonjyu, Korea, 11/27-30. Slide
2025/9/24	oral Invited	The 2025 Dalian International Conference on Mathematics, “Error analysis of the ensemble Kalman filter for chaotic dynamical systems with covariance inflation techniques”, Dalian, China, 9/21-25.
2025/7/14	oral Invited	Workshop on Sampling Methods for Problems Involving Differential Equations and Physical Sciences, Efficient Sampling Algorithms for Complex Models 1, “Uniform error bounds of the ensemble square root filter for chaotic dynamics with multiplicative covariance inflation”, National University of Singapore, Singapore, 7/14-18.
2025/7/10	oral	The Third HKSIAM Biennial Conference, “Error analysis of the ensemble Kalman filter for chaotic dynamical systems with covariance inflation techniques”, The Chinese University of Hong Kong, Hong Kong SAR, China, 7/7-11.
2025/3/13	oral Invited	Synergies of Machine Learning and Numerics, “Error analysis and numerical issues in data assimilation”, Osaka University, Japan, 3/11-13.
2024/11/20	oral Invited	The 1st MMS Workshop for Young Researchers, “Uniform error bounds of the ensemble square root filter for chaotic dynamics with multiplicative covariance inflation”, Kyoto University, Japan, 2024/11/20-21. Slide
2024/11/3	oral Invited	Applied Mathematics Freshman Seminar 2024, “Mathematical analysis of data assimilation and related topics”, Kyoto University, Japan, 2024/11/2-4. Slide
2024/9/16	poster	The CRC International Summer School, “Error analysis of the ensemble square root filters with multiplicative inflation for dissipative dynamical systems”, Boltenhagen, Germany, 2024/9/16-20.
2024/6/30	oral	The 17th SIAM East Asia Section Conference, “Mathematical Analysis of the Ensemble Kalman filter”, Macao SAR, 2024/6/28-7/1.
2024/3/14	oral Invited	DA Seminary at IMT Atlantique, “Theoretical aspect of the ETKF and covariance inflation”, IMT Atlantique Brest, France.
2024/2/28	poster	SIAM Conference on Uncertainty Quantification (UQ24), “Rigorous analysis of the ensemble transform Kalman filter for chaotic dynamical models”, Trieste, Italy, 2/27-3/1.
2024/1/29	poster	The 6th R-CCS International Symposium, “Mathematical analysis of the ensemble transform Kalman filter for chaotic dynamics with multiplicative inflation”, RIKEN R-CCS Kobe, Japan, 1/29-1/30.
2023/12/9	poster Invited	NCTS-Kyoto Mathematics Symposium, “Mathematical Analysis of Data Assimilation to Chaotic Dynamics”, National Center for Theoretical Science, Taiwan.
2023/12/7	oral	Dynamics Days 2023 Kagurazaka, “Ensemble data assimilation to infinite-dimensional nonlinear dynamics with noisy observations”, Tokyo, Japan 12/4-8.
2023/11/8	oral	Twentieth International Conference on Flow Dynamics, “A Monte Carlo approach to the N-vortex problem on the unit sphere”, Sendai, Japan, 11/6-8.
2023/8/30	poster	14th Data Assimilation workshop, “Mathematical analysis of the ensemble transform Kalman filter with covariance inflation”, RIKEN R-CCS Kobe, Japan.
2023/8/29	oral Invited	IMT-Atlantique & Kyoto University & RIKEN joint Data Assimilation workshop, “Ensemble filter with the optimal transport of gaussian mixture distributions”, RIKEN R-CCS Kobe, Japan.
2023/8/22	oral	ICIAM 2023 Tokyo, SIAM Student Chapter Research Presentations, “Computing the invariant measure of the N-vortex problem on the sphere by Hamiltonian Monte Carlo”, Waseda University, Japan, 8/20-25.
2023/7/31	poster	TDA week 2023, “Topological Regularization in Numerical Simulation”, Kyoto University, Japan, 7/31-8/4.
2023/2/6	poster	The 5th R-CCS International Symposium, “Computing the invariant measure of the N-vortex problem on the unit sphere”, RIKEN R-CCS Kobe, Japan.
2023/1/24	oral Invited	Conference ‘Mathematical Structure in Quantum Fluids’, “A Monte Carlo approach to the N-vortex problem on the unit sphere”, Osaka Metropolitan University, Japan, 1/23-25.
2023/1/9	poster Invited	East Asian Core Doctoral Forum on Mathematics 2023, “Efficient sampling method on compact manifolds and its application to turbulent statistics on the unit sphere”, National Taiwan University, Taiwan, 1/9-12.

in Japanese »

Activities