chap 6

Distinguish between coastal upwelling and equatorial upwelling.

Coastal upwelling is the process where wind blows along a coastline. The wind causes the water at the ocean surface to move away from the coast, because of a process called Ekman transport. When surface water moves away from the coast, water from deeper in the ocean rises up and takes its place. Equatorial upwelling is the process where trade winds at the Equator blow surface water both north and south, allowing upwelling of deeper water.

Describe the role played by Ekman transport in coastal upwelling.

Coastal upwelling occurs where Ekman transport moves surface waters away from the coast; surface waters are replaced by water that wells up from below.

How and why do coastal upwelling and downwelling affect sea-surface temperature?

Coastal upwelling transfers the cold water from below the photic zone to the surface of the water. In contrast, coastal downwelling transfers the warmer surface water down. This process will alter the sea-surface temperature.

Describe the relationship between trade winds and biological productivity along the equator.

The trade winds converge near the equator and the consequent Ekman transport away from the equator gives rise to upwelling. Coastal upwelling transports waters rich in dissolved nutrients from the ocean depths into the photic zone where sunlight penetrating the water supports the growth of phytoplankton populations. Down-welling reduces biological productivity and transports heat, dissolved materials, and surface waters rich in dissolved oxygen to greater depths.