日本語 [Japanese]

Tomoki IWAKIRI

Ph.D.
Postdoctoral Associate, IPRC, University of Hawai‘i at Mānoa, USA.
JSPS Oversea Research Fellowship
Tomoki Iwakiri
Climate science
I am a Postdoctoral Associate at the International Pacific Research Center (IPRC), University of Hawai‘i at Mānoa, where I work with Malte F. Stuecker.

Previously, I worked at Seoul National University, Ochanomizu University, and Meteorological Research Institute, with Jong-Seong Kug, Tsubasa Kohyama, and Yukiko Imada. I received my Ph.D. under the supervision of Masahiro Watanabe, studying the dynamics of long-persistent ENSO.

My primary research topic lies in large-scale atmosphere–ocean interactions across past, present, and future climates, with an emphasis on ENSO dynamics, tipping elements such as the AMOC and Snowball Earth, and irreversible responses. I am currently expanding my research toward broader, long-standing questions in climate science, including climate sensitivity, feedback, and SST pattern problem.

My research philosophy is to seek simple understanding of the complex climate system. To this end, I enjoy developing and using conceptual models that complement and help interpret evidence from observations and comprehensive climate models.

Personal
Born in 1995 Jan, Japan
Primary email
iwakirit (at) hawaii.edu
Permanent email (transfer to Primary)
iwakiri.tmk (at) gmail.com

ORCID

Publication list

Submitted Articles
  • Iwakiri T. and Stuecker M.F. et al.: Manuscript on derivative form of ENSO RO theory, in revision.
  • Iwakiri T. and Kug J-S.: Manuscript on ENSO periodicity changes, in revision.
  • Iwakiri T. and Kug J-S. et al.: Manuscript on the emergent oceanic mode associated with AMOC slowdown, in revision.
  • Iwakiri T. and Kohyama T.: Manuscript on multi-year ENSO impact on GMST, in revision.

Peer-Reviewed Journal Articles (Lead author)
  1. Iwakiri T., Kug J-S., Jin F-F., Zhao S., An S-I., Kim G-I., Park D. (2025): Abrupt shift of El Niño periodicity under CO2 mitigation. Proc. Natl. Acad. Sci., https://doi.org/10.1073/pnas.2426048122.
    Featured in the PNAS Showcase | More frequent El Niño events due to climate mitigation
  2. Iwakiri T., Imada Y., Takaya Y., Kataoka T., Tatebe H., and Watanabe M. (2023): Triple-dip La Niña in 2020–23: North Pacific atmosphere drives 2nd year La Niña. Geophys. Res. Lett., https://doi.org/10.1029/2023GL105763.
  3. Iwakiri T. and Watanabe M. (2022): Multiyear ENSO dynamics as revealed in observations, climate model simulations, and the linear recharge oscillator. J. Climate, https://doi.org/10.1175/JCLI-D-22-0108.1.
  4. Iwakiri T. and Watanabe M. (2021b): Contribution of Ekman transport to the ENSO periodicity estimated with an extended Wyrtki index. Geophys. Res. Lett., 48, https://doi.org/10.1029/2021GL095193.
  5. Iwakiri T. and Watanabe M. (2021a): Mechanisms linking multi-year La Niña with preceding strong El Niño. Sci. Rep., 11, https://doi.org/10.1038/s41598-021-96056-6.
  6. Iwakiri T. and Watanabe M. (2020): Multiyear La Niña impact on summer temperature over Japan. J. Meteor. Soc. Japan., 98, https://doi.org/10.2151/jmsj.2020-064.
  7. Iwakiri T. and Watanabe M. (2019b): Strengthening of the Indian Ocean dipole with increasing seasonal cycle in the mid-Holocene. Geophys. Res. Lett., 46, https://doi.org/10.1029/2019GL083088.
  8. Iwakiri T. and Watanabe M. (2019a): Mechanisms reducing ENSO amplitude and asymmetry via an enhanced seasonal cycle in the mid-Holocene. J. Climate, https://doi.org/10.1175/JCLI-D-19-0110.1.

Peer-Reviewed Journal Articles (coauthor)
  1. Xu, Z., Kosaka Y., Toda M., Iwakiri T., Huang G., Ji F., Miyamoto A., and Tao W. (2024): Irreversibility of winter precipitation over the Northeastern Pacific and Western North America against CO2 forcing. npj Clim. Atmos. Sci., https://doi.org/10.1038/s41612-024-00864-2.
  2. Hu, S., Watanabe M., Zhang W., Iwakiri T., and Jiang F. (2024): Quantifying the Amplifying Effect of the Winter North Pacific Oscillation on the Subsequent ENSO. Geophys. Res. Lett., https://doi.org/10.1029/2024GL111019.
  3. Watanabe, M., Iwakiri T., Dong Y., and Kang S. M. (2023): Two competing drivers of the recent Walker circulation trend. Geophys. Res. Lett., https://doi.org/10.1029/2023GL105332.

Others
  1. MIROC6 AGCM Document Writing Team (2021), Description of MIROC6 AGCM , CCSR Report No. 65, Division of Climate System Research, Atmosphere and Ocean Research Institute, The University of Tokyo. https://doi.org/10.15083/0002000180.

Career

2025-07 → present  : Postdoctoral Associate, IPRC*1, University of Hawai‘i at Mānoa, USA (Host: Malte Stuecker)
2026-02 → present  : JSPS*2 Oversea Research Fellowship (Host: Malte Stuecker)
2024-04 → 2026-01 : JSPS Research Fellow (PD), Ochanomizu university, Japan (Host: Tsubasa Kohyama)
2024-05 → 2025-04 : Postdoctoral Researcher, Seoul National University, South Korea (Host: Jong-Seong Kug)
2023-04 → 2024-03 : JSPS Research Fellow (PD), JMA/MRI*3, Japan (Host: Yukiko Imada & Yuhei Takaya)
2023-04 → 2024-03 : Adjunct lecturer for calculus, Ochanomizu university, Japan
2022-04 → 2023-03 : Visiting Researcher, JMA/MRI, Japan
2022-04 → 2023-03 : JSPS Research Fellow (PD), The University of Tokyo (Host: Masahiro Watanabe)
2021-04 → 2022-03 : JSPS Research Fellow (DC2), The University of Tokyo (Host: Masahiro Watanabe)
2019-08 → 2019-09 : Intern student, RIKEN (Host: Data Assimilation Team)

*1 IPRC : International Pacific Research Center
*2 JSPS : Japan Society for the Promotion of Science (Funding agency for scientists)
*3 JMA/MRI : Japan Meteorological Agency/Meteorological Research Institute

Professional services

2023-08 → present : Associate Editor : Journal of Climate

Education

2022 Mar - Ph.D. (Science) - The University of Tokyo, Japan

Dissertation: "Mechanisms for multi-year ENSO"
Supervisor: Masahiro WATANABE

2019 Mar - M.S. (Science) - The University of Tokyo, Japan

Thesis: "Mechanisms of changes in ENSO and IOD in the mid-Holocene"
Supervisor: Masahiro WATANABE

2017 Mar - B.S. (Science) - Nihon University, Japan

Thesis: "Representativeness of wind data from AMeDAS in Kanto region" (In Japanese)
Supervisor: Hisashi KATO


Award

  • Yamamoto award, Meteorological Society of Japan (MSJ), 2023.
  • Outstanding student presentation award, Japan Geoscience Union (JpGU), 2021 annual meeting.
  • Matsuno award (student presentation award), Meteorological Society of Japan (MSJ), 2019 spring meeting.