What drives the formation of deep ocean currents according to thermohaline circulation?

The formation of deep ocean currents is primarily driven by differences in temperature and salinity, which are key components of thermohaline circulation. This process involves the movement of water due to variations in density, which is influenced by both temperature (thermo) and salinity (haline) levels.

When surface water evaporates, it often becomes saltier and denser, causing it to sink to greater depths. Similarly, cold polar regions have water that is colder and can also be saltier due to sea ice formation, leading to the sinking of this denser water. As a result, these density differences facilitate the movement of water throughout the ocean, creating deep ocean currents that are critical for regulating climate, distributing nutrients, and supporting marine life.

In contrast, factors like wind forces and tides mainly affect surface currents rather than the deep ocean currents that characterize thermohaline circulation. Earth’s rotation affects the Coriolis effect, influencing current patterns but not driving the thermohaline circulation itself. Solar radiation plays a significant role in warming surface waters but does not directly contribute to the formation of the deep currents governed by temperature and salinity variations. Therefore, temperature and salinity differences accurately describe the driving forces behind deep ocean currents.