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Difficulty: HardPhysical Geography of the World

Consider the following statements regarding the physical mechanisms and climate impacts of major oceanic currents:

1. Cold ocean currents along the western coasts of continents in subtropical belts are associated with coastal upwelling driven by Ekman transport.
2. The Agulhas Current is a cold, equatorward-flowing ocean current located along the western coast of Southern Africa.
3. Cold ocean currents chill the overlying air mass and induce thermal stability, inhibiting atmospheric convection and contributing to coastal desertification.

Which of the statements given above is/are correct?

  1. 1 and 3 onlyAnswer
  2. B
    2 only
  3. C
    1 and 2 only
  4. D
    1, 2 and 3

Answer

Statements 1 and 3 only are correct.
The combination of Statements 1 and 3 only is correct. Ekman transport drives coastal upwelling along subtropical western coasts where offshore surface drift brings cold subsurface waters upward. This low ocean surface temperature cools the lower atmosphere, creating stable air layers (temperature inversion) that suppress precipitation and generate coastal deserts. Statement 2 is false because the Agulhas Current is a warm ocean current located along Africa's eastern coast.

Step-by-Step Solution

1
Analyze Statement 1 regarding Ekman transport and upwelling
In the subtropics, trade winds driving ocean surface waters combined with the Coriolis effect cause net water transport away from western continental coastlines (Ekman transport). Deep, cold, nutrient-rich ocean water rises to replace it. Statement 1 is correct.
Verify oceanographic forcing mechanisms of coastal upwelling.
2
Evaluate Statement 2 regarding the Agulhas Current
The Agulhas Current is a warm, poleward-flowing (southward) western boundary current in the southern Indian Ocean off the eastern coast of Africa. The cold current on the western coast of Southern Africa is the Benguela Current. Statement 2 is incorrect.
Distinguish between eastern and western oceanic boundary currents and their regional geography.
3
Analyze Statement 3 regarding atmospheric stability and climate impact
Cold surface ocean waters cool the air directly above them. Air near the surface becomes colder and denser than the air above, creating a atmospheric temperature inversion. This halts convection, prevents cloud growth, and inhibits precipitation, yielding coastal desert conditions. Statement 3 is correct.
Examine air-sea thermodynamic interaction and atmospheric stability.

Key Concept

Oceanic Currents, Ekman Transport, and Coastal Microclimates
Estimated Time:2m 0s
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Topics

Physical Geography of the World

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