Ekman Spiral Boundary layer flow under horizontal homogeneous condition Assuming steady state and neglecting thermodynamic effect, Using K-theory Further assuming Boundary conditions

Is usually defined as the depth of the Ekman layer. Atmosphere: Ocean:

Oceanic Ekman layer Boundary condition: Solution:

Ekman transport The integrated water mass transport is at layer Ekman layer Ekman transport The integrated water mass transport is at the right angle, 90 degree, to the wind direction, known as Ekman transport.

4. Ocean gyre Westerlies North Pacific gyre Easterlies

Estimate vertical secondary circulation Is the depth of the Ekman layer. The integrated cross isobaric mass transport of the entire Ekman layer is

x y Hurricane

Secondary circulation Boundary layer Ekman pumping Inflow Frictional Pressure grad. force Centrifugal force Pressure grad. force Centrifugal force Secondary circulation Frictional force Inflow Pressure grad. force Centrifugal force Boundary layer Ekman pumping

Hurricane Vortex X L Converging Spin up Diverging Spin down Ekman Pressure grad. force Coriolis force L Centrifugal force Converging Spin up Diverging Spin down Buoyancy X Ekman Pumping Boundary Layer It is the convective clouds that generate spin up process to overcome the spin down process induced by the Ekman pumping