Research Interests

• Kuroshio/Kuroshio Extension

• Oyashio

• Surface Water Masses (Mode Waters)

• Atmosphere-Ocean Interactions

Publications

• Usui, N., Hirose, N., Sakamoto, K., Asai, H., Nishikawa, S., Igarashi, H., Kawakami, Y., Aoki, K., Nakano, H., and Ishikawa, Y. (2026):
  Four-dimensional variational ocean reanalysis for the seas around Japan over 60 years (FORA-JPN60):Part I - system configuration and basic performance.
  Journal of Oceanography, in press.
  https://doi.org/10.1007/s10872-026-00795-x 

• Aoki, K., Nakano, H., Hirose, N., Usui, N., Sakamoto, K., Toyoda, T., Urakawa, S., and Kawakami, Y. (2026):
  Application of variational autoencoder-based clustering for geophysical fluid circulations with small smaple size.
  Journal of Geophysical Research: Machine Learning and Computation, 3,  e2025JH001051
  https://doi.org/10.1029/2025JH001051

• Ushijima, Y., Sakamoto, K., Yagi, K., Kawakami, Y., Togawa, H., Sasaki, H., and Fukuda, Y. (2026):
  Marine heatwave around Japan over the past four decades: links to interannual-to-decadal variability of sea surface temperature.
  Journal of Oceanography, in press
  https://doi.org/10.1007/s10872-026-00787-x 

• Ushijima, Y., Nakano, H., Sakamoto, K., Mizuta, R., Kawakami, Y., and Tsujino, H. (2026):
  Upper-ocean warming in the subtropical North Pacific Ocean due to the intensified Kuroshio Extension in the eddying model compared to the non-eddy-resolving model.
  Journal of Climate, in press
  https://doi.org/10.1175/JCLI-D-25-0060.1

• Kawakami, Y., Hirose, N., Nakano, H., Urakawa, L. S., Aoki, K., Hirahara, S., and Toyoda, T. (2025):
  Oceanic cool spot formed off Boso Peninsula in the late June 2022.
  Journal of Oceanography, in press
  https://doi.org/10.1007/s10872-025-00768-6

• Toyoda, T., Urakawa, L. S., Sakamoto, K., Kawakami, Y., Aoki, K., Nakano, H., Takaya, Y., Toyama, K., Kosugi, N., Kitamura, Y., and Ishii, M. (2025):
  Sensitivity of the Arctic sea ice representation to the ice thickness category resolution in an OGCM.
  Journal of Oceanography, 81, 273-288
  https://doi.org/10.1007/s10872-025-00748-w 

• Sugimoto, S., Kojima, A., Sakamoto, T., Kawakami, Y., and Nakano, H. (2025):
  Influence of Extreme Northward Meandered Kuroshio Extension during 2023–2024 on Ocean-Atmosphere Conditions in the Sanriku offshore region, Japan
  Journal of Oceanography, 81, 203-215
  https://doi.org/10.1007/s10872-025-00747-x 

• Toyoda, T., Hirose, N., Sakamoto, K., Nakano, H., Urakawa, L. S., Kawakami, Y., Aoki, K., Yamagami, A., Ushijima, Y., Usui, N., Yamanaka, G., Nakayama, T., In, T., Kuji, T., Kofuji, H., and Tanaka, T. (2025):
  Bottom topography effect on the seasonal mode generation of the Tsugaru Warm Current.
  Journal of Climate, 38, 1791-1811
  https://doi.org/10.1175/JCLI-D-24-0124.1

• Nakano, H., Urakawa, L. S., Aoki, K., Kawakami, Y., and Hirahara, S. (2025):
  On the speeding up and accuracy of the Second Order Moment (SOM) advection scheme using a mixed-precision method.
  Ocean Modeling, 194, 102495
  https://doi.org/10.1016/j.ocemod.2024.102495

• Kawakami, Y., Nakano, H., Urakawa, L. S., Toyoda, T., Aoki, K., Hirose, N., and Usui, N. (2025):
  Temporal changes of the Oyashio water distribution east of Japan under the changing climate: development of an objective evaluation method and its application.
  Journal of Oceanography,  81, 5-21
  https://doi.org/10.1007/s10872-024-00727-7

• Kawakami, Y., Nakano, H., Urakawa, L. S., Toyoda, T., Sakamoto, K., Nishikawa, S., Sugiyama, T., Kurogi, M., Ishikawa, Y., Sato, K., and Yamanaka, G. (2024):
  Future changes in marine heatwaves based on high-resolution ensemble projections for the northwestern Pacific Ocean.
  Journal of Oceanography, 80, 177-195
  https://doi.org/10.1007/s10872-024-00714-y

• Toyoda, T., Sakamoto, K., Toyota, T., Tsujino, H., Urakawa, L. S., Kawakami, Y., Yamagami, A., Komatsu, K. K., Yamanaka, G., Tanikawa, T., Shimada, R., and Nakano, H. (2024):
  Improvements of sea ice thermodynamics with variable sea ice salinity and melt pond parameterizations in an OGCM.
  Ocean Modelling, 187, 102288
  https://doi.org/10.1016/j.ocemod.2023.102288

• Kawakami, Y., Nakano, H., Urakawa, L. S., Toyoda, T., Aoki, K., and Usui, N. (2023):
  Northward shift of the Kuroshio Extension during 1993－2021.
  Scientific Reports, 13, 16223
  https://doi.org/10.1038/s41598-023-43009-w

• Toyoda, T., Urakawa, L. S., Aiki, H., Nakano, H., Shindo, E., Yoshimura, H., Kawakami, Y., Yamagami, A., Ushijima, Y., Harada, Y., Kobayashi, C., Tomita, H., Tozuka, T., and Yamanaka G. (2023):
  Effective generation mechanisms of tropical instability waves as represented by high-resolution coupled atmosphere-ocean prediction experiments.
  Scientific Reports, 13, 14742
  https://doi.org/10.1038/s41598-023-41159-5 

• Sakamoto, K., Nakano, H., Urakawa, S., Toyoda, T., Kawakami, Y., Tsujino, H., and Yamanaka, G. (2023):
  Reference manual for the Meteorological Research Institute Community Ocean Model version 5 (MRI.COMv5).
  Technical Reports of the Meteorological Research Institute, 87
  https://doi.org/10.11483/mritechrepo.87

• Kawakami, Y., Nakano, H., Urakawa, L. S., Toyoda, T., Sakamoto, K., Yamanaka, G., and Sugimoto, S. (2023):
  Cold- versus warm-season-forced variability of the Kuroshio and North Pacific subtropical mode water.
  Scientific Reports, 13, 256
  https://doi.org/10.1038/s41598-022-26879-4

• Nakano, H., Urakawa, L. S., Sakamoto, K., Toyoda, T., Kawakami, Y., and Yamanaka, G. (2023):
  Long-term sea-level variability along the coast of Japan during the 20th century revealed by a 1/10° OGCM.
  Journal of Oceanography, 79, 123-143
  https://doi.org/10.1007/s10872-022-00671-4

• Kawakami, Y., Nakano, H., Urakawa, L. S., Toyoda, T., Sakamoto, K., Yoshimura, H., Shindo, E., and Yamanaka, G. (2022):
  Interactions between ocean and successive typhoons in the Kuroshio region in 2018 in atmosphere-ocean coupled model simulations.
  Journal of Geophysical Research: oceans, 127, e2021JC018203
  https://doi.org/10.1029/2021JC018203

• Kawakami, Y., Kojima, A., Murakami, K., Nakano, T., and Sugimoto S. (2022):
  Temporal variations of net Kuroshio transport based on a repeated hydrographic section along 137°E.
  Climate Dynamics, 59, 1703-1713
  https://doi.org/10.1007/s00382-021-06061-8

• Toyoda, T., Sakamoto, K., Usui, N., Hirose, N., Tanaka, K., Katsumata, T., Takahashi, D., Niki, M., Kutsuwada, K., Miyama, T., Nakano, H., Urakawa, L. S., Komatsu, K. K., Kawakami, Y., and Yamanaka G. (2021):
  Surface-layer circulations in Suruga Bay induced by intrusions of Kuroshio branch water.
  Frontiers in Marine Science, 8, 721500
  https://doi.org/10.3389/fmars.2021.721500

• Kawakami, Y., Kitamura, Y., Nakano, T., and Sugimoto, S. (2020):
  Long‐term thermohaline variations in the North Pacific subtropical gyre from a repeat hydrographic section along 165°E.
  Journal of Geophysical Research: oceans, 125, e2019JC015382
  https://doi.org/10.1029/2019JC015382

• Kawakami, Y., Sugimoto, S., and Suga, T. (2016):
  Inter-annual zonal shift of the formation region of the lighter variety of the North Pacific Central Mode Water.
  Journal of Oceanography, 72, 225-234
  https://doi.org/10.1007/s10872-015-0325-1