Winds along the Peruvian coast blow towards the north, and since Peru is in the Southern Hemisphere, the Ekman transport is 90 o to the left of the wind, which causes the surface water to move offshore and leads to upwelling and productivity. In any coastal upwelling location, if the winds reverse, surface water moves towards the shore and downwelling is the result.
Upwelling can also occur due to geological features of the ocean floor. For example, as deep water currents encounter seamounts or other raised features, the water is forced upwards, bringing nutrient-rich water to the surface. This helps explain why productivity is often high in the water over seamounts. Skip to content The movement of surface currents also plays a role in the vertical movements of deeper water, mixing the upper water column.
Figure 9. Coastal Upwelling. Previous: 9. Next: 9. Wallace and S. Download image jpg, 43 KB. When the wind blows parallel to a coastline, surface waters are pushed offshore and water is drawn from below to replace the water that has been pushed away.
The upward movement of this deep, colder water is called upwelling. The deeper water that rises to the surface during upwelling is rich in nutrients. These phytoplankton serve as the ultimate energy base in the ocean for large animal populations higher in the food chain, providing food for fish, marine mammals, seabirds, and other critters.
These nutrients are then available for marine life. Upwellings are when cold, dense water that is rich in nutrients is moved to the surface by wind combined with the Corolis effect and Ekman transport.
The Corolis effect describes how objects move when considering earth's rotation and the Ekman transport is the movement of fluid by wind forcing. Upwellings replenish nutrients to the surface and increase productivity. The nutrients then attract marine life. You can read more about upwellings here. What are upwellings, and how do they benefit marine life? Kate M.
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