Module 11: The Hydrosphere: Oceans

ocean

the reservoir of salt water that covers 71 percent of Earth’s surface

sea

a body of salt water largely surrounded by land but connected to the world ocean

bathymetry

the measurement of ocean depth, for the purpose of mapping seafloor topography

continental shelf

the submerged area of a continent that lies between the coast and the upper continental slope

continental slope

the portion of the seafloor that slopes steeply away from the continental shelf and ends in the continental rise

continental rise

a sediment-covered region of the seafloor that rises from the abyssal plain to meet the continental slope

phytoplankton

microscopic plants that float at or near the surface of water columns and lie at the base of aquatic food chains

photic zone

(or euphotic zone)

Ekman transport

the movement of water to the left of the wind direction in the southern hemisphere and to the right in the northern hemisphere as a result of the Coriolis effect

upwelling

the upward movement of water from the deep ocean toward the surface in response to Ekman transport of surface water; this process delivers dissolved nutrients to the surface ocean

downwelling

the downward movement of water from the surface toward the deep ocean in response to Ekman transport of surface water; this process delivers dissolved oxygen to the deep ocean

gyres

clockwise (northern hemisphere) and counterclockwise (southern hemisphere) circulation cells within the surface ocean produced by the drag of the winds on the ocean surface and the continental boundaries of the ocean basins

thermohaline circulation

the density-driven circulation of the whole ocean in response to temperature and salinity variations at the surface