ocean circulation

Components of the Climate System

• Atmosphere• Ocean

• Biosphere• Geosphere

Image from NASA

Atmosphere & Ocean Circulation

• Atmospheric Circulation– Depends on density

• Ocean Surface Circulation– Depends on the wind

• Deep Ocean Circulation– Depends on density

Why is Ocean Circulation Important?

• Transport ~ 20% of latitudinal heat– Equator to poles

• Transport nutrients and organisms

• Influences weather and climate

• Influences commerce

Temperature Structure of Ocean

thermocline

Ocean circulation patterns – Wind

Ocean circulation patterns – Surface Currents

Ocean Circulation

Winds and Currents• How fast? A few miles/hr (Gulf Stream

off of Miami = 4.5 mph)

• How much? Total water in ocean surface circulation = about 100 Amazon Rivers (20 million m3/s).

Atmosphere & Ocean Circulation

• Atmospheric Circulation– Depends on density

• Ocean Surface Circulation– Depends on the wind

• Deep Ocean Circulation– Depends on density

Sea Surface Temperature

http://www.ldeo.columbia.edu/dees/ees/climate/slides/sst_march.gif

Ocean Salinity

http://www.ldeo.columbia.edu/dees/ees/climate/slides/sal_march.gif• http://ingrid.ldgo.columbia.edu/

Temperature-Salinity (density) Diagram

Thermohaline circulation

The Great Conveyor        The conveyor circulation transports heat to the North Atlantic. The sinking which takes place is susceptible to changes in surface salinity. If the surface of the North Atlantic gets too fresh, NADW won’t sink.

Global warming could increase melting of ice caps and sea ice, causing more fresh water to enter the Atlantic. Many models suggest that a shutdown of the conveyor would cause cooling over the North Atlantic and Europe.   The conveyor has been off in the past during global cold periods, such as the last ice age and during the Younger Dryas. One hypothesis is that the shutdown of the conveyor, coupled with resultant atmospheric changes, is enough to throw the world into an ice age - or at least a cold snap.

Thermohaline Circulation

North Atlantic Deep Water

(NADW

15 million m3 of near surface water descend into the deep ocean each second.

Thermohaline Circulation - The Ocean Conveyor

Equatorial to polar heat transport and water flow

Ocean – Atmosphere Circulation

ENSOEl Niño/Southern Oscillation

3-7 year cycle of warming in E. Pacific

ENSO

El Niño/Southern Oscillation

NASA/Goddard Space Flight CenterScientific Visualization Studio

ENSO

El Niño/Southern Oscillation

http://svs.gsfc.nasa.gov/vis/a000000/a000200/a000287/index.htmlNASA/Goddard Space Flight CenterScientific Visualization Studio