Salinity and Ocean Circulation

Yuck! If you have ever swallowed a mouthful of seawater, you know two things: it tastes terrible, and it is filled with salt. But, why is seawater so salty, and how does that salt affect the way water moves in the ocean?

In this topic, you will learn about salinity, which is a term scientists use to describe the amount of dissolved substances in seawater. You will also learn how salinity affects the density of ocean water and how salinity and density influence the global circulation of ocean water, called currents. There are two types of currents that carry ocean water around the Earth. Deep ocean currents depend on salinity and density while surface currents are driven by the wind. Both surface and deep water currents are important because they influence the long term and short terms climates on land across the Earth.

Essential Questions

• What is salinity, and how does salinity differ in the oceans?
• What forces cause surface ocean circulation?
• What forces cause deep water circulation?
• What are El Niño Southern Oscillation and La Niña?