What primarily drives deep ocean currents?

What primarily drives deep ocean currents?

• A. Temperature only
• B. Wind stress at the surface
• C. Salinity alone
• D. Density differences in water masses

Answer: (D)

Deep ocean currents are driven by differences in water density. Water becomes denser when it is colder and/or saltier, so very cold, salty water sinks in polar regions and spreads along the ocean floor. This density-driven sinking and spreading creates a global overturning circulation, often called thermohaline circulation. While wind at the surface shapes the upper, wind-driven currents, it doesn’t set the deep return flow. Temperature and salinity both affect density, but the force that moves water deeply through the oceans is the resulting density differences in water masses.

Deep ocean currents are driven by differences in water density. Water becomes denser when it is colder and/or saltier, so very cold, salty water sinks in polar regions and spreads along the ocean floor. This density-driven sinking and spreading creates a global overturning circulation, often called thermohaline circulation. While wind at the surface shapes the upper, wind-driven currents, it doesn’t set the deep return flow. Temperature and salinity both affect density, but the force that moves water deeply through the oceans is the resulting density differences in water masses.