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BCCR Monday Seminar 8th September: " Wave-driven ocean currents: how ocean responds to Stokes transport"

Time

08. September 2025, 09:00-10:00

Location

BCCR seminar room (4th floor of the West wing)

This BCCR Monday Seminar will be given by Yasushi Fujiwara from Kobe University. He will present his work on " Wave-driven ocean currents: how ocean responds to Stokes transport". Abstract

Stokes drift associated with surface waves induces mass transport that interacts with ocean currents. Its effects can be represented in governing equations as external forcings such as Coriolis-Stokes and vortex forces. While pointwise current responses (anti-Stokes Eulerian current) have long been studied, nonlocal responses to spatially varying waves remain less understood. Here, using linearized wave-averaged theory, we show that inhomogeneous Stokes transport induces horizontal convergence/divergence, driving nonlocal geostrophic responses via effective Ekman pumping. Idealized simulations reveal dipole circulation around localized Stokes forcing, and over sloping topography, transient forcing excites topographic Rossby waves that irreversibly modify geostrophic currents. A simulation with realistic topography and wave forcing shows Lagrangian transport of O(1) m^2/s persisting for days after a cyclone.

About the speaker

Yasushi Fujiwara is an Assistant Professor at Kobe University, Japan. He received his Ph.D. in Physical Oceanography from Kyoto University, Japan. His research focuses on small-scale processes in the oceanic boundary layer, particularly wave–current interactions, surface wave dynamics, wind–wave coupling, and their representation in numerical models. He primarily investigates these problems using numerical approaches, notably through a wave-phase-resolved model that explicitly simulates the interaction between turbulence and wave motions.

Zoom details https://uib.zoom.us/j/62554083320?pwd=w66YFoIhFNBTjgDA4bKppdlKAzpOoj.1

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