MAST 637 Exam 2 Deep Circulation

Depth Range of Deep Ocean

• Deep ocean starts at 200 meters to nearly 11,000 meters

• Divided into bathyal, abyssal, and hadal zones

• Average depth is roughly 3,682 meters

Thermocline

Distinct, thin layer in large bodies of water where the temperature decreases rapidly with depth, separating warmer, mixed surface water from colder, dense deep water

Halocline

where salinity changes rapidly with depth, creating a boundary between less salty surface water and denser, saltier deep water

Pycnocline

a distinct layer within a body of water where water density increases rapidly with depth

Mixed Layer

is the top turbulent surface layer where water properties-temperatures, salinity, and density - are nearly homogenous due to atmospheric forcing and mixing

Potential Temperature

The temperature a water parcel would attain if moved without heat exchange to a reference pressure, typically the sea surface

Potential Density

The density a water parcel would acquire if moved without heat exchange to a reference pressure, usually the sea surface

Major Atlantic Water Masses

are classified by density, temperature, and salinity, forming a layered structure from surface to bottom. Key masses include (top to bottom)

• Central Atlantic Surface Water

• Antarctic Intermediate Water

• North Atlantic Deep Water

• Antarctic Bottom Water

Why is there no deep water forming in the modern North Pacific?

Low surface salinity, caused by high precipitation and low evaporation creates a strong, buoyant, and stable freshwater layer that prevents water from becoming dense enough to sink