Japan Geoscience Union Meeting 2019

Presentation information

[E] Poster

A (Atmospheric and Hydrospheric Sciences ) » A-OS Ocean Sciences & Ocean Environment

[A-OS09] Ocean Mixing Processes: Impact on Biogeochemistry, Climate and Ecosystem

Sun. May 26, 2019 3:30 PM - 5:00 PM Poster Hall (International Exhibition Hall8, Makuhari Messe)

convener:Ichiro Yasuda(Atmosphere and Ocean Research Institute, The University of Tokyo), Toshiyuki Hibiya(Department of Earth and Planetary Science, Graduate School of Science, University of Tokyo), Jun Nishioka(Hokkaido University, Institute of low temperature sciences), Shin-ichi Ito(Atmosphere and Ocean Research Institute, The University of Tokyo)

[AOS09-P04] Mixing processes observed by a slocum glider at the Oyashio-TWC front

*Daisuke Hasegawa1, Takahiro Tanaka1, Takeshi Okunishi1, Ichiro Yasuda2 (1.Tohoku National Fisheries Research Institute, Japan Fisheries Research and Education Agency, 2.Atmosphere and Ocean Research Institute, The University of Tokyo)

Keywords:double diffusion, mixing, cabbeling

In order to grasp the detailed mixing processes along the frontal region between the Oyashio and the Tsugaru Warm Current (TWC), we conducted a zigzag survey crossing the front several times from the merging region of the two current systems to the down stream by an underwater glider (Slocum G2 Glider) equipped with a turbulence sensor, from July 24thto August 29thin 2017. The observed frontal structure indicated the subduction and the intrusion processes of the cold and fresh Oyashio water under the warm and salty TWC water, along layer between 26.5 to 26.8 sigma-theta, which resulted the favorable conditions to the salt finger convection at the upper interface along the 26.5 sigma-theta, and the diffusive convection at the lower interface along the 26.8 sigma-theta where the fresh and cold Oyashio water lying above the warm and salty water. The strong turbulence intensity is observed around the intruded layer, and the mean temperature and the salinity in the layer became warmer and saltier with the increase of the distance from the front, which suggested the time evolution of the vertical mixing driven by double diffusive convections between the three different water masses. Though the strongest turbulence intensity was observed around the frontal region, which may suggest the importance of the cabbeling effect as the additional source of the turbulent mixing.