Part A

The world and environment we live in has many limitations and causes the relationships we have today. Because of this, researchers are unable to function in certain environments. However, even with 70% of the world covered by water (Earth - How Much, 2014), the deep oceans are still greatly unknown to scientists. Nevertheless, understanding the properties and physical principles of the limiting factors of the ocean such as temperature, salinity, buoyancy, density and pressure will allow researchers to overcome and explore further.

When exploring the deep oceans, temperature is a key factor which needs to be considered. Temperature can be defined as being the measure of heat (The World Book Encyclopaedia, 2007). Temperature in the ocean plays a role which impacts both the explorer, along with the salinity and density level (The Ocean and Temperature, 2014). Temperature impacts on the ocean through converting light energy from the sun when it strikes the surface, to heat energy (The Ocean and Temperature, 2014). However, the sun can only penetrate to a small depth causing the deeper depths to decrease in temperature. With a decrease in temperature, the volume of the water also decreases (About Water Temperatures). Figure 1 describes the relationship between temperature and depth.

Figure 1 indicates that the thermocline or rapid decrease in temperature (About Water Temperatures), starts at approximately 300m and ends at 1000m. This reveals that the sun’s heat can only penetrate to 300m. As the depth increases from 300m to 1000m, the temperature rapidly decreases, after that, the temperature continuous to slowly decrease. Therefore, as the depth increases, a greater affect occurs on salinity and density.

Figure 1: Temperature and Depth Relationship

Salinity is another key aspect when investigating the deep oceans. Salinity is defined as being the measurement of salt dissolved in a solvent (Salinity, 2014). This needs to be considered when exploring the depths as salinity impacts the density of the water, by increasing mass (Seawater Density and Salinity, 2013). The salinity level decreases as the depth increases due to, this can be seen in Figure 2.

Figure 2 indicates that the halocline or great decrease in salinity (Ocean Properties, 2010-2013) occurs from approximately the surface and ends at 500m. However, after the halocline, the depth increases and so does salinity. This is due to the temperature and density at increased depth. Therefore, depth impacts salinity, and must be considered when investigating the deep oceans.

Figure 2: Salinity and Depth Relationship

Density is one of the crucial factors which need to be studied when exploring the deep oceans. Density is the measure of how compact a material is; more precisely, density is the mass of the object divided by the volume or ρ=m/v (Elert, 1998-2014). Therefore, according to this equation density is proportional to mass, meaning when mass increases so does density. Furthermore, density is inversely proportional to volume, as when volume increases, density decreases. These calculations can be seen in Appendix A. The density of water can be affected by both salinity and temperature, by impacting both mass and volume. Figure 3 describes the relationship between density and depth.

Figure 3 specifies that the pycnocline or dramatic increase in density (Ocean Properties, 2010-2013) starts at the surface and ends at approximately 1000m. While after the pycnocline, the depth increases, however the density remains the same. Therefore, at depths, density is another feature which must be studied when exploring deep oceans.

Figure 3: Density and Depth Relationship

Buoyancy is another key factor which must be considered when going into the depths of the ocean. Buoyancy is defined as being the upward force which is placed upon an object either completely or partly in fluid (Elert, Buoyancy, 1998-2014). The buoyant force of