Ekman Spiral

Wind-driven ocean currents rotating with depth due to Coriolis force

Latitude φ: 45° Wind speed: 8.0 m/s Eddy viscosity Kz: 0.0100 m²/s

Ekman (1905) solved the geostrophic wind-driven flow: u(z)=V₀e^(z/D)[cos(z/D+π/4), sin(z/D+π/4)], where D=√(2Kz/f) is the Ekman depth and f=2Ω sin(φ) is the Coriolis parameter. Surface current is 45° to the right of wind (NH). Net Ekman transport is exactly 90° to wind, driving coastal upwelling and gyres.