upward movement of deep (abyssal), cold water to the surface.
an upward flow of cold, heavy deep-sea water caused as offshore currents draw away warm surface water. The deep-sea water of upwellings is generally rich in nutrients.
Movement of nutrient-rich bottom water to the ocean's surface. This can occur far from shore but usually occurs along certain steep coastal areas where the surface layer of ocean water is pushed away from shore and replaced by cold, nutrient-rich bottom water.