Objectives: In this lab we explore the physical mechanisms of ocean circulation, first with some simple lab experiments, and then by applying our experiments to actual data from the world’s oceans. The purpose of the first part of the lab is to allow you to see for yourself the role of temperature, salinity and winds in driving ocean circulation by conducting experiments in an aquarium. You will see how water masses are formed, how currents develop, and how currents are deflected by the boundaries of the aquarium. This will give you valuable insights into the nature of ocean circulation. Next, you will apply this knowledge by looking at the actual circulation system in the world’s oceans, and some causes and effects of this circulation.

Reading: Skinner, Porter & Botkin, The Blue Planet Chap. 11: p.244-255.

rainbow.ldeo.columbia.edu/ees/

Background: The principal factors governing ocean circulation are temperature, salinity, and surface wind. Ocean circulation consists of thermohaline circulation and wind-driven circulation. Thermohaline circulation is driven by differences in water mass density. Water is more dense when its temperature (thermo) is cold, and when its salinity (halo) is high. Cold and saline water tends to sink, while warm and relatively fresh water will float on top of more dense water. Very dense water may sink to the ocean floor and flow along it. If a water mass forms of intermediate density, it will sink to its own density level and spread out along this surface. Density differences in the ocean result in currents that flow from one region to the next.