Evaluate the factors influencing global ocean surface current circulation: Statement I: Gyres in the Northern Hemisphere circulate in a clockwise direction, driven primarily by planetary wind belts and deflected by the Coriolis force. Statement II: Ekman transport causes net surface water movement at an angle of 90 degrees to the direction of the overlying wind in deep open ocean waters. Which of the following is correct?

💡 Solution & Explanation

Statement I is correct because subtropical ocean gyres rotate clockwise in the Northern Hemisphere and counter-clockwise in the Southern Hemisphere due to geostrophic balance and Coriolis deflection. Statement II is incorrect because while individual water layers spiral via the Ekman spiral, the net mass transport of water integrated over the entire friction depth is precisely 90 degrees to the right of the wind in the Northern Hemisphere, but the surface layer itself moves at 45 degrees. Ocean current patterns dictate global heat distribution and marine climate stability.