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Basic
Dynamics |
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Ekman transport |
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Geostrophic Currents |
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Conservation of potential vorticity |
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Surface
Ocean Circulation |
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Subtropicl gyre |
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boundary current |
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Deep
Ocean Circulation |
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Thermohaline conveyor belt |
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Temperature |
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warm
on the upper ocean, cold in the deeper ocean. |
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Salinity |
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variations
caused by determined by evaporation, precipitation, sea-ice formation and
melt, and river runoff. |
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Density |
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small
in the upper ocean, large in the depper ocean. |
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Currents are in geostropic balance |
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Each gyre includes 4 current components: |
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two
boundary currents: western and eastern |
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two
transverse currents: easteward and westward |
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Western boundary current (jet stream of ocean) |
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the fast, deep, and narrow current moves warm water polarward (transport ~50 Sv or greater) |
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Eastern boundary current |
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the
slow, shallow, and broad current moves cold water equatorward (transport ~
10-15 Sv) |
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Trade wind-driven current |
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the moderately shallow and broad westward current (transport ~ 30
Sv) |
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Westerly-driven current |
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the wider and slower (than the trade wind-driven current) eastward
current |
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Western Boundary Current |
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Gulf
Stream (in the North Atlantic) |
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Kuroshio Current (in the North Pacific) |
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Brazil Current (in the South Atlantic) |
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Eastern Australian Current (in the South Pacific) |
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Agulhas Current (in the Indian Ocean) |
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Eastern Boundary Current |
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Canary
Current (in the North Atlantic) |
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California Current (in the North Pacific) |
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Benguela Current (in the South Atlantic) |
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Peru Current (in the South Pacific) |
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Western Australian Current (in the Indian Ocean) |
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Mixed Layer |
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Currents
controlled by frictional force + Coriolis force |
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à
wind-driven circulation |
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à Ekman
transport (horizontal direction) |
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à
convergence/divergence |
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à
downwelling/upwelling at the bottom of mixed layer |
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Thermocline |
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downwelling/upwelling
in the mixed layer |
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à pressure
gradient force + Coriolis force |
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à
geostrophic current |
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à Sverdrup
transport (horizontal) |
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Surface Water |
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to
a depth of about 200 meters |
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Central Water |
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to
the bottom of the main thermocline |
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Intermediate Water |
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to
about 1500 meters |
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Deep Water |
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below intermediate water but not in |
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contact with the bottom |
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Bottom Water |
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in
contact with sea floor |
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Notes