Deep Ocean Circulation

1

http://nssdc.gsfc.nasa.gov/planetary/image/earth_day.jpg

Sunlight

Effect of Solar Radiation on Sea Surface Temperature

Modified image from Windows to the Universe, http://www.windows.ucar.edu

2

Sea Surface Temperature

oceanworld.tamu.edu

3

4

Surface Currents

Sea to AirHeat TransferSea to AirHeat Transfer

Deep Ocean Currents Driven by Density of Seawater

What effects water density?•Colder water Denser (to 4°C)•Saltier water Denser

melindawebster.comhawaiianphotos.net

5

Deep water forms when:

● Surface water flows to the poles and gets colder● When seawater freezes it leaves salt behind, increasing salinity● Water becomes denser and sinks

6

http://oceanexplorer.noaa.gov/

Modeling cold salty water sinking

7

8

Sinking Cold,Salty WaterSinking Cold,Salty Water

Global Conveyor Belt

Courtesy NASA/JPL-Caltechhttp://sealevel.jpl.nasa.gov/index.html

9

Global Conveyor Belt

Thermohaline Circulation– Thermo = temperature– Haline = salinity

10

Why is thermohaline circulation important?

• Major influence on climate

• Transfers heat from equator to poles

• Nutrient cycling• Brings oxygen to

deep ocean organisms

11

SurfaceOcean

DeepOcean

Boundary

12

Cold, Dark, No Photosynthesis, More Nutrients

O2(oxygen)

Oxygen (O2) USED

O2

Photosynthesis

PRODUCED in surface oceanMixed with atmosphere

O2 O2

O2 O2

Mixed

Warmed and lit by sun

Less Nutrients

How will global climate change affect thermohaline circulation?

• Melting of sea ice

• Increased precipitationDecrease in

salinityMay alter

thermohaline circulationinformify.com

13