Effects of Western Boundary Currents on Climate
Why is London so much warmer than Chicago when London is located further north (latitude 51N) than Chicago (latitude 41N)? In most cases, higher elevations, higher latitudes, and further inland locations have colder climates but the average temperature in London (59.4°F/15.2°C) is ten degrees warmer than Chicago (49°F/9.4°C). The figure below shows the difference in latitude between London and Chicago and the relative temperature differences.
You can see how the average temperature is warmer as you cross the Atlantice from the US to Europe. The Gulf Stream bringing warm water north to Europe is dominant factor in temperate climate of London. Its amazing how much energy is transported poleward via western boundary currents.
Western Boundary Currents
Western boundary currents play an important role in transporting heat poleward. Without the Gulf Stream (the western boundary current in the North Atlantic Ocean) parts of Europe would be much colder. Each western boundary current is part of a larger ocean gyre but the western boundary is intense compared to that on east.
Below is an interactive map of ocean gyres and western boundary currents. move the cursor over the locations to see the names.
The next question you might have is "Why are the western currents so concentrated compared to those on the eastern boundary?" To answer this question we will look at the basics of ocean surface currents. The existence of western boundary currents such as the Gulf Stream can be explained by the Stommel Model in the next section.