The Myth of Separation: How Two Oceans Interact Despite the Lack of Physical Boundaries

The separation of two oceans, despite the absence of a physical boundary, can be attributed to several complex factors. While it might seem straightforward to assume that two bodies of water would always mix, this is not the case due to the intricate interplay of water density, temperature, currents, geographical features, and biological and chemical differences.

Water Density and Temperature

Differences in water density and temperature are key factors that contribute to the separation of two oceans. For example, warmer water is less dense than colder water, and saltier water is denser than fresher water. These differences create distinct layers within the water that resist mixing. Cooler, saltier water tends to sink below warmer, fresher water, leading to stratification and preventing mixing between the layers.

Currents

Ocean currents play a crucial role in maintaining the separation between different bodies of water. For instance, the Gulf Stream, a powerful current in the Atlantic Ocean, flows northward and is warmer than the surrounding waters. The cold Labrador Current, on the other hand, flows southward, bringing cooler water into the region. These currents act as barriers that prevent the mixing of water masses from different parts of the ocean.

Geographical Features

The shape of ocean basins, which are influenced by continental landmasses, naturally separate oceans. The ocean floor is also shaped by underwater ridges and trenches, which affect water circulation and interaction. These geographical features can create further barriers that prevent the mixing of ocean water from different regions.

The Coriolis Effect

The Earth’s rotation influences ocean currents through the Coriolis effect, causing them to curve. This can lead to distinct circulation patterns in different oceans, further preventing mixing. The Coriolis effect ensures that water in the northern and southern hemispheres moves in different directions, creating unique hydrological behaviors that maintain the separation of ocean water.

Biological and Chemical Differences

Different oceans can support varying marine ecosystems and have different chemical compositions, which can further contribute to their separation. The biological activity in one ocean can be very different from that in another, leading to diverse chemical profiles that prevent full mixing.

Ocean Do Mix: The Gulf of Alaska Case Study

While there are instances where oceans do not mix due to the factors mentioned above, the Gulf of Alaska provides a unique case study where the mixing process is disrupted. On February 5th, 2013, a news article was published titled, 'Mythbusting the place where two oceans meet in the Gulf of Alaska.' This article highlighted an intriguing natural phenomenon where heavy sediment-laden water from glacial valleys and rivers pours into the open ocean, diluting the water due to the influx of fresh water.

Let's evaluate this as a simpler example. When considering two liquids, the primary mechanisms of mixing are liquid-liquid diffusion and physical agitation. Diffusion is a very slow process in liquids, taking days for solutes to travel even a few centimeters. Therefore, in oceans, mixing is dominated by physical agitation caused by forces such as waves, currents, and wind.

At the ocean-ocean interface, the densities of the water can be significantly different due to variations in salinity. This can create a salt wedge at the interface but ultimately, the highly agitated ocean due to wind, waves, and temperature-density variations leads to the formation of currents that break down the barrier, leading to mixing. In extreme cases, such as when there is a heavy supply of water with other properties, the mixing process can take a long time.

Conclusion

In conclusion, while there are several factors that contribute to the separation of two oceans, the complex dynamics of water density, temperature, currents, geographical features, and biological and chemical differences ensure that these oceans maintain distinct characteristics. However, the processes of diffusion and physical agitation ensure that mixing does occur, albeit often over a longer period.

References

Source of information:

Mythbusting the place where two oceans meet in the Gulf of Alaska