Lecture 14 - Ekman transport

Question 1

What is Ekman transport?

Answer 1

The net movement of water in the wind-affected layer (Ekman layer), at 90° to the wind direction.

Question 2

In which direction does Ekman transport occur?

Answer 2

90° to the right of the wind in the Northern Hemisphere, 90° to the left in the Southern Hemisphere.

Question 3

What causes Ekman transport?

Answer 3

A balance between wind stress and the Coriolis force.

Question 4

What is wind stress (τ) and its units?

Answer 4

The force per unit area exerted by wind on the ocean surface; units: N m⁻².

Question 5

How is wind stress calculated?

Answer 5

τ=CD⋅ρa ⋅W^2

where:
CD is drag coefficient,
ρ a is air density,
W is wind speed.

Question 6

What is the Ekman layer depth (De)?

Answer 6

De= Sqrt ( 2K / [f] )
where:

K is eddy viscosity and

f is the Coriolis parameter.

Question 7

What happens when surface Ekman transport diverges?

Answer 7

Upwelling occurs — deeper water rises to the surface

Question 8

What happens when surface Ekman transport converges?

Answer 8

Downwelling occurs — surface water sinks.

Question 9

What is the formula for Ekman transport velocity?

Answer 9

ve = - tx / pDef

ue = ty / p*De * f

Question 10

What are some real-world examples of Ekman-induced upwelling?

Answer 10

Coastal upwelling and equatorial upwelling (e.g., due to trade winds near the equator).