Which type of global ocean circulation is driven by differences in temperature and salinity?

Thermohaline circulation is the type of global ocean circulation driven by differences in temperature and salinity. This process is often referred to as the "global conveyor belt" and is crucial in regulating Earth's climate by redistributing heat and nutrients around the oceans.

In thermohaline circulation, the density of seawater, which depends on its salinity and temperature, plays a significant role. Regions where water becomes cold and salty—such as at high latitudes—cause the water to become denser, leading it to sink. This downward movement helps create a global loop of ocean currents that can travel thousands of miles across oceans, contributing to the mixing of surface and deep waters, which affects marine ecosystems and global climate patterns.

The other types of circulation mentioned, like surface currents and gyre circulation, primarily involve wind-driven currents and do not incorporate the deeper connections influenced by temperature and salinity. Similarly, trade winds are specific wind patterns that affect surface currents but are not themselves a form of circulation based on temperature and salinity. Hence, thermohaline circulation, uniquely, connects the properties of water to its movement across the globe.