Significance of surface circulation
Surface currents move heat toward poles
In tropics, westward currents cause water to ‘pile up’ along the W sides of ocean basins
- Have dynamic topography - currents control the elevation of water surface
- Dynamic topographic high on W side of basins depresses the pycnocline
- Dynamic topographic low on E side of basin elevates the pycnocline, & may draw deep zone waters to surface (creating upwellings along eastern sides of ocean basins)
- Topography leads to subtle ocean currents, e.g. the equatorial countercurrent & undercurrent