Which of the following terms refers to the process of nutrient-rich water rising to the ocean surface?

The process of nutrient-rich water rising to the ocean surface is known as upwelling. This phenomenon occurs when winds blow across the ocean surface, pushing the warmer, surface waters away and allowing deeper, colder water that is rich in nutrients to rise and replace it. This upwelling is crucial for marine ecosystems because the nutrients that come from the deep water can support the growth of phytoplankton, which forms the basis of the oceanic food web.

In contrast, downwelling refers to the sinking of water, where surface waters converge and move downward, typically bringing oxygen but not nutrients from deeper layers. The thermocline is a layer in ocean water characterized by a rapid change in temperature with depth, while estuarine flow describes the movement of water between the ocean and estuaries, which are areas where freshwater meets saltwater. These other processes are important in their own right, but they do not specifically refer to the upward movement of nutrient-rich water.