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
- Okajima, S., H. Nakamura, Y. Kaspi: Cyclonic and anticyclonic contributions to atmospheric energetics, Scientific Reports, 11, 13202, 2021. Journal Site
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
- 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
- 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
- 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
- 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
Large-scale atmospheric response to midlatitude SST anomalies
- 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
- 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
- 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
- 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