[A-OS15] Physical Oceanography (General)

[AOS15-02] Cyclones and near inertial internal waves in the abyssal Japan Sea
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*Akie Sakai¹, Tomoharu Senjyu² (1.Department of Earth System Science and Technology, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 2.Research Institute for Applied Mechanics, Kyushu University)

Keywords:Near inertial internal waves, cyclone

The near inertial internal waves (NIWs) are observed intermittently in the abyssal the Japan Sea. The intensification mechanism of NIWs was discussed by Senjyu and Shin (2021). In this study, the current observations at six layers were conducted at Stn. PM5S (37.37º N, 134.41º E) from October 2019 to November 2020 to investigate overall picture of intensified NIWs.

The NIWs with large amplitude were observed at 916 m and deeper than 2400 m depth for a few weeks in October and February. The flow in the upper (916 m) layer and in deep (lower than 2400 m) layers were opposite. These results show that the observed NIWs with large amplitude are the intensified NIWs discussed in Senjyu and Shin 2021.

However, there were some periods that large amplitude of NIWs were observed only at 916 m depth. The paths of cyclones and current in the mixed layers were estimated to investigate the difference between the two types of the periods. Several weeks before the intensified NIWs were observed, the cyclones were traveled eastward and current in the surface mixed layers was excited around two degrees north from the Stn. PM5S. This suggests that the NIWs at the deep (lower than 2400 m) layers were excited at the northern area of the Stn. PM5S.
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