Ocean Circulation

Salinity•Amount of salts and minerals dissolved in water

•Varies throughout•Average = 35 ppt or 3.5%

Density•Salt water is more dense than fresh water

•Cold water is more dense than warm water

•Pycnocline – area of rapid increase in density with depth

Temperature•Warm water expands and stays above colder water

•Only fresh water evaporates or freezes. The salt is left behind.

•Thermocline – area of rapid decrease in temperature as depth increases

Pressure•Increases with depth•Every 33 feet = 1 atmosphere

Waves

•Wind speed•Wind duration•Fetch (distance over which wind blows)

Surface Circulation•Controlled by temperature, wind, and coriolis effect

Currents Affect Climate

•Warm currents make warmer climates

•California vs. East Coast•Gulf Stream warms Europe

Climate Affects Currents

•Global warming & cooling can alter currents

•Changes in precipitation or evaporation can change salinity and density

Deep Ocean Currents

•Controlled by density differences and the pull of the moon

Circulation Cells – Not

Convection!• Heat source is above the water not below

Water Masses

• Distinctive combinations of temperature and salinity

Upwelling