the oceans nov. 18 topics thermohaline circulation –sst; –ocean water masses wind-driven...
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The OceansNov. 18
Topics
•Thermohaline circulation–SST; –ocean water masses
•Wind-driven circulation–Wind-driven upwelling–Surface currents
Mundus SubterraneusA. Kirchner, 1665
Temperature 0m
Stephens et al., NOAA, 2002
Salt content of the oceans
• Source: leaching ions from crustal material. Global river dissolved load is ~0.1 ppt. Residence time: 108yr
• Salinities for the open ocean fall in the range 33-38ppt (parts per thousand, mass per unit mass)
http://omp.gso.uri.edu/doee/science/physical/salt5.gif
Salinity 0m
Water masses {sort of like air masses}
http://earth.usc.edu/~stott/Catalina/images/weatherimages.jpg/airmasses.jpg
Arctic sea ice
http://www.ccpo.odu.edu/~arnoldo/ocean405/arcticdrift.jpg
At 70N, Tromsö and Hammarfest ice-free year-round
February September
Deepwater formation processes
http://puddle.mit.edu/~helen/oodc.html
1. preconditioning
2. Violent mixing
3. Sinking and spreading
Where it happens
Zonal average Temperature and salinity
Levitus, 1984
Tem
pera
ture
salin
ity
Transport units:
smSv /1011 36
Spatial distribution of deep and bottom water masses
(Lynne Talley, SIO)
Model of the overturning circulation
Broecker, 1980sReproduced in Ocean Circulation
Wind-driven circulation
Surface winds
Trenberth et al., JPO, 1990
tropical winds, rain
From Ocean Circulation and Climate (OCC)
Ekman transport
Transports associated with winds
Where water piles up:
Mean surface currents
Simulated sea surface temperature