RESEARCH

I am working on various research topics, focusing on midlatitude storm track dynamics and air-sea interactions over the oceanic frontal zones.

Contributions from Cyclonic and anticycloinic vortices to energetics

  1. Okajima, S., H. Nakamura, Y. Kaspi: Cyclonic and anticyclonic contributions to atmospheric energetics, Scientific Reports, 11, 13202, 2021. Journal Site
Introductory articles:

Migratory cyclones and anticyclones

I have developed a tracking program to objectively identify tracks of migratory cyclone/anticyclone centers based on atmospheric reanalyses and climate model outputs.
I have processed data such as monthly-mean density of migratory cyclone and anticyclone centers, as well as raw track data. If you are interested in the data, please send an e-mail to me.
mail: okajima(at)atmos.rcast.u-tokyo.ac.jp

"Midwinter suppression" or "midwinter minimum (MWM)" of the North Pacific storm-track activity


Seaonality of the density of migratory surface cyclones and anticyclones

  1. Okajima, S., H. Nakamura, Y. Kaspi: Distinct roles of cyclones and anticyclones in setting the midwinter minimum of the North Pacific eddy activity: a Lagrangian perspective, J. Climate, in press.Journal Site

Energetics

  1. Okajima, S., H. Nakamura, Y. Kaspi: Energetics of transient eddies related to the midwinter minimum of the North Pacific storm-track activity, J. Climate, 2022.Journal Site

Relative importance of cyclonic and anticyclonic contributions

  1. Okajima, S., Nakamura, H., Kaspi, Y. (2024). Anticyclonic suppression of the North Pacific transient eddy activity in midwinter. Geophys. Res. Lett., 51, e2023GL106932. Journal Site

In relation to the long-term modulation of "Bomb" cyclones

  1. Kuwano-Yoshida, A., S. Okajima, H. Nakamura: Rapid increase of explosive cyclone activity over the midwinter North Pacific in the late 1980s, J. Climate, 2022.Journal Site
Introductory articles:

Large-scale atmospheric response to midlatitude SST anomalies

  1. Okajima, S., H. Nakamura, K. Nishii, T. Miyasaka, A. Kuwano-Yoshida, B. Taguchi, M. Mori, Y. Kosaka: Mechanisms for the Maintenance of Wintertime Basin-Scale Atmospheric Response to Decadal SST Variability in the North Pacific Subarctic Frontal Zone, J. Climate, 31, 297-315, 2018. Journal Site
  2. Okajima, S., H. Nakamura, K. Nishii, T. Miyasaka, A. Kuwano-Yoshida: Assessing the importance of prominent warm SST anomalies over the midlatitude North Pacific in forcing large-scale atmospheric anomalies during 2011 summer and autumn, J. Climate, 27, 3889-3903, 2014. Journal Site

Impact of fine-scale SST or fronts over WBC region on atmosphere

  1. Masunaga, R., H. Nakamura, H. Kamahori, K. Onogi, S. Okajima: The JRA-55CHS: An atmospheric reanalysis constructed with high-resolution sea surface temperature, SOLA, 14, 2018, 6-13. Journal Site
  2. Okajima, S., Nakamura, H., Spengler, T. (2024). Midlatitude oceanic fronts strengthen the hydrological cycle between cyclones and anticyclones. Geophysical Research Letters, 51, e2023GL106187.Journal Site