Lab 5.1 – How does salinity and temperature change with water depth over time?

Estimated time to complete: 30 minutes

Materials needed: none

The ocean is layered like a cake according to differences in temperature and salinity. The layering of the ocean (and the differences in temperature and salinity) occur in response to processes that occur at the surface of the ocean as a result of seasonal change. The processes include the gain or loss of heat, increase in evaporation or precipitation, freezing and thawing of sea ice, and the increase in wind strength and storms that are associated with the change of seasons. We can “see” the ocean layers by measuring temperature and salinity with depth and can make inferences about the processes at the ocean surface by observing how temperature and salinity change over time at a location.

In this activity, you will explore how the layering of the ocean at one location changes over the course of a year.

Below you are able to see a dataset of temperature and salinity with pressure (depth) at the Coastal Pioneer Array over the course of a year. You can interact with the data by:

  • Viewing the data (temperature, salinity) for one or more months by clicking on that month under the “Toggle Month” menu at right of graphs
  • Hovering your mouse over a profile to view the value of data variables at different water depths


Interpretation Questions:

  1. Describe how the depth range of the thermocline, halocline, and surface mixed layer changes throughout the year at this location.
  2. During which season (summer or winter) is the mixed layer depth deeper?
  3. Suggest an explanation for the seasonal difference in the depth of the surface mixed layer.