How Does Temperature Affect The Density Of Deep Ocean Currents?

Deep ocean currents derive their energy from the thermohaline circulation. Thermohaline circulation is the result of changes in temperature and salinity. A decrease in temperature leads to an increase in the density of water, due to less kinetic energy. An increase in salinity introduces salt crystals into the gaps between water molecules which in turn increases the density of sea water (Cruse 2015). Typically with increasing depth in the ocean temperature decreases and salinity increases. These interactions form what is called the pycnocline zone in the ocean. The pycnocline zone combines the density increases from decreased temperatures and increased salinity, resulting in a strong pressure gradient between surface and deep ocean layers (Hernandez-Malina et al., 2016). Having dense water below and less dense water above leads to stable and stratified layers for the majority of Earth’s oceans.

The density of surface waters at the pole is greatly increased due to the low temperatures. Additionally icebergs are composed of fresh water as salt water has a lower freezing point. Accessible pure water is frozen, and the remaining surface water increases in salinity. At the poles the dense water at the surface will push through the less dense water below. The buildup of dense water at the surface around the poles is referred to as ‘bottom water’, because it sinks to the bottom of the ocean. Bottom water represents one of the major drivers for thermohaline circulation and the horizontal distribution of deep ocean currents (Cruse