Surface currents in the oceans move in response to global winds. Therefore, the direction of the surface currents is dependent upon the direction the wind is blowing. There are three bands of global winds in each of the northern and southern hemispheres. The trade winds are closest to the equator and blow from east to west; they drive the ocean surface currents from the east to west as well. The prevailing westerlies are found at mid-latitudes and move from west to east, creating surface currents that also move in that direction. The polar easterlies are closest to the poles and blow from east to west, pushing surface currents westward.


However, ocean surface currents do not blow in a straight line like the global winds because their movement is impeded by the continents and affected by Earth's rotation (Coriolis Effect). Instead, they flow in a circular pattern, referred to as gyres. Gyres in the northern hemisphere flow in a clockwise direction while gyres in the southern hemisphere flow in a counterclockwise direction. The next page will allow you to further explore the connection between Earth's global winds and ocean surface currents.



Source: Teachers' Domain, Examine Global Surface Currents, published December 17, 2005, retrieved on June 16, 2010, http://www.teachersdomain.org/resource/ess05.sci.ess.earthsys.globalsurf/