Ocean Density and Stratification

Physical Ocean Processes

In this course, Dr Katy Sheen (University of Exeter) explores physical ocean processes. In the first module, we think about the how differences in the density of water masses drive movement and vertical stratification within the oceans. In the second module, we look at the world’s major surface ocean currents and their drivers, and in the third we turn to ocean gyres – very large circular currents which dominate the surface layer of the oceans. The fourth module focuses on how water moves vertically upwards and downwards within the oceans, and why this is significant. We conclude with a fifth module on the overturning global circulation – the large-scale vertical exchange of water between the interior ocean and the surface.

Ocean Density and Stratification

In this module, we think about how differences in the density of water masses drive movement and stratification within the oceans. We focus on: (i) the key external drivers of movement within the oceans, such as wind and solar heating; (ii) how density variations cause motion through vertical stratification, including a tank experiment to demonstrate this; (iii) what produces differences in the density of water masses, most importantly temperature and salinity; (iv) the three main strata of the ocean – the surface mixed layer, the pycnocline, and the interior ocean; (v) methods for measuring the temperature and salinity (and therefore density) of water masses.