Final answer:
The thermohaline current's position in the ocean, whether near the surface or at the bottom, is determined by water density, which is influenced by both temperature and salinity. Warm, less dense water tends to stay near the surface, while cold, dense water tends to sink, contributing to the complex circulation patterns that affect global climate.
Step-by-step explanation:
The major factor determining whether the thermohaline current flows near the surface or on the bottom of oceans is primarily dictated by the water's density, which is affected by both temperature and salinity. As the ocean absorbs solar energy, especially around the equator, it heats up and becomes less dense, resulting in what's known as thermal expansion. This less dense, warmer water tends to stay near the surface. In contrast, in regions such as the Southern Ocean's Subtropical Convergence, cold, dense water from the south sinks beneath the warmer, less dense water from the north, creating conditions for a deeper thermohaline circulation.
The thermohaline circulation system plays a critical role in the world's climate by redistributing heat and maintaining the temperature balance between different regions.
Factors like thermal expansion, temperature gradients, and salinity affect the ocean currents and, by extension, climate patterns and sea levels worldwide.