What circulation pattern describes the rise of deep, cold, nutrient-rich water to the surface?

What circulation pattern describes the rise of deep, cold, nutrient-rich water to the surface?

• A. Upwelling
• B. Downwelling
• C. Mixing
• D. Turbidity

Answer: (A)

Upwelling is the vertical movement where deep, cold, nutrient-rich water rises toward the surface. When winds along a coast push surface water away, Ekman transport causes surface waters to move offshore and must be replaced by water from below. That deep water brings nutrients like nitrates up into the sunlit zone, fueling phytoplankton growth and boosting primary productivity, which is why upwelling regions are so biologically productive. Downwelling is the opposite process, with surface water sinking and nutrients often being carried away from the surface. Mixing describes general blending of water layers, not a sustained upward transport from depth, and turbidity relates to how clear the water rather than any circulation pattern.

Upwelling is the vertical movement where deep, cold, nutrient-rich water rises toward the surface. When winds along a coast push surface water away, Ekman transport causes surface waters to move offshore and must be replaced by water from below. That deep water brings nutrients like nitrates up into the sunlit zone, fueling phytoplankton growth and boosting primary productivity, which is why upwelling regions are so biologically productive. Downwelling is the opposite process, with surface water sinking and nutrients often being carried away from the surface. Mixing describes general blending of water layers, not a sustained upward transport from depth, and turbidity relates to how clear the water rather than any circulation pattern.