North Pacific Deep Water

North Pacific Deep Water is a component of the global thermohaline circulation, which is driven by variations in water density caused by exchanges of heat and salinity between the ocean and atmosphere. This deep water originates from the mixing of North Atlantic Deep Water with Southern Ocean water. It upwells in the North Pacific at depths of 2,000–3,000 meters.1

Thermohaline circulation involves the sinking of cold, dense water in polar regions, primarily in the North Atlantic and near Antarctica. This dense water spreads throughout the ocean and gradually upwells, creating a slow return flow. In the North Pacific, this deep water is characterized by lower salinity and oxygen content but higher nutrient concentrations compared to the surface waters. The flow of bottom waters is generally slow, typically 1 to 2 centimeters per second, though it can be faster along the western margins of ocean basins.12