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OC103 Lesson 15 Ocean Surface Currents Circulation in the oceans is ruled by two very different things Global wind patterns drive currents on the ocean surface while seawater density variations drive deep ocean circulation This lesson covers the surface ocean currents and the next one covers the deep circulation The most prominent surface ocean currents are shown on the map below Notice how the currents circulate around large areas of the ocean basins Although these currents are wind driven it is not as simple as you might think or hope But before getting into that let s cover how we know where the currents go Measuring Surface Ocean Currents There are several ways to monitor and measure the direction and speed of surface ocean currents In some areas oceanographers deployed buoys that are anchored to the bottom and have current meters attached that can measure the speed and direction of the passing current It is not usually necessary to constantly measure the currents in one spot since they do not vary much from year to year so this approach is only practical in areas where a buoy was going to be deployed anyway say for weather or wave height monitoring The typical way to determine currents in various parts of the ocean is to do temporary experiments for a month or two by deploying neutrally buoyant floats that ride around wherever the currents take them The location of the buoys can be monitored by satellite so the paths and speeds of the currents can be determined A third method is similar to the neutrally buoyant float experiments but is unplanned and usually accidental This is called a floats of opportunity study and consists of tracking the paths of a bunch of floating objects over the course of months or years The floating objects are usually something that was accidentally spilled off a ship at some known point in the ocean at some known time usually during a bad storm By putting the word out among beachcombers that they should report the location and date