Japan Geoscience Union Meeting 2024

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[J] Oral

A (Atmospheric and Hydrospheric Sciences ) » A-CG Complex & General

[A-CG40] Dynamics of Oceanic and Atmospheric Waves, Vortices, and Circulations

Wed. May 29, 2024 1:45 PM - 3:00 PM 106 (International Conference Hall, Makuhari Messe)

convener:Yohei Onuki(Research Institute for Applied Mechanics, Kyushu University), Yukiharu Hisaki(University of the Ryukyus), Norihiko Sugimoto(Keio University, Department of Physics), Takuro Matsuta(Faculty of Env.Earth Science, Hokkaido University), Chairperson:Yohei Onuki(Research Institute for Applied Mechanics, Kyushu University), Yukiharu Hisaki(University of the Ryukyus), Norihiko Sugimoto(Keio University, Department of Physics), Takuro Matsuta(Faculty of Env.Earth Science, Hokkaido University)

2:30 PM - 2:45 PM

[ACG40-04] Importance of the surface geostrophic shear stress on eddy-induced Ekman pumping in the Kuroshio-Oyashio confluence region

*Kento Usui1, Tomoki Tozuka1 (1.University of Tokyo)

Keywords:Mesoscale eddies, Ekman pumping

Mesoscale eddies are ubiquitous in the global ocean and their associated vertical motions strongly affect biogeochemical distributions and thermal structures in the upper ocean by vertically transporting nutrients and heat. Previous studies showed that such vertical motion is partly due to Ekman pumping induced in eddy interiors by the existence of relative vorticity gradient and by the wind stress curl created by eddy-induced spatial sea surface temperature (SST) variability. However, the existence of geostrophic shear associated with eddy-induced spatial SST variability, which affects the ageostrophic Ekman response by partially balancing with the wind stress, was overlooked. Using satellite observations, the relative importance of this effect is investigated in the eddy-rich Kuroshio-Oyashio confluence (KOC) region. It is found that the effect of the surface geostrophic shear is comparable in magnitude with the known mechanisms of eddy-induced Ekman pumping and therefore warrants consideration.