What is the strong western boundary current of the North Atlantic, off the Atlantic coast of the United States?

• A. Gyre
• B. Flow Method
• C. Equatorial Upwelling
• D. Gulf Stream

Answer: (D)

The key idea is that western boundary currents are fast, narrow flows that move warm tropical waters poleward along the western edge of an ocean basin because the Coriolis effect deflects the path of surface water to the right in the Northern Hemisphere. In the North Atlantic, this strong boundary current sits along the Atlantic coast of the United States and is known as the Gulf Stream. It sources warm water from the Caribbean and Gulf of Mexico, flows northward along the coast, and feeds into the broader North Atlantic Drift toward Europe, shaping climate by keeping western Europe warmer than its latitude. The other terms don’t describe a coastal current: a gyre is the large circular system that the Gulf Stream helps form, equatorial upwelling occurs near the equator away from the U.S. coast, and “Flow Method” is not a current name.