Major currents, gyres, rings, andeddies (basin scale). Winds and wind-driven basin circulation: Meanders, rings, eddies and gyresThe thermohaline circulation
Major currents, gyres, rings, and eddies (basin scale) • Winds and wind-driven basin circulation • Meanders, rings, eddies and gyres • The thermohaline circulation
Windsandwind-drivenbasin circulationWinds60°7WesterliesUnevenly heating30°NSubtropicathighsby the sunNortheasttradesSpinning sphereIntertropicalconvergencezaneSoutheasttradesSubtropicathighs30°5ts60°5Fig.8.01Majorwindsystemsoftheworld
Winds Unevenly heating by the sun Spinning sphere Winds and wind-driven basin circulation
30EEoa0eIS0"W180°W20150°E60°E80*N80*Subpolarovxe70°Strongandnarrow50*N60°Nwestern boundar50*Ncurrent50"40°NSubtropica30'NSubtropicalgyre20"NgyreO"NOatariatCo105SEustori1020S2030°5340°51050°550'60°5OSJOYBO'S80*590°E30°E60°1o60°W30rW120°W90"W150°W90°E120°E150°E180"W60"EFig,8.03 The principal surface currents of the world's oceans.Western boundary currents such as the Gulf Streamare emphasizedPositions ofoceanweather shipsB(Bravo),56.5N51.oeW;1 (lndia),59.0eN19e W:J (Juliett)
Subtropical gyre Strong and narrow western boundary current Subtropical gyre Subpolar gyre
1. The Coriolis force causes the moving water to be deflectedto the right of the right of the wind (in NH). The net effectof winds in the upper ocean is a flow perpendicular to thewind (i.e. Ekman transport).2. The strong western boundary currents are formed due to thevariation of the Coriolis parameter with latitudeCD1000hm000WindstressFIG.9.12 Flow patterns (streamlines)for simplified wind-driven circulation with: (a) Coriolisforce zero or constant, (b)Coriolisforce increasing linearly withlatitude.(From Stommel,1948.)
1. The Coriolis force causes the moving water to be deflected to the right of the right of the wind (in NH). The net effect of winds in the upper ocean is a flow perpendicular to the wind (i.e. Ekman transport). 2. The strong western boundary currents are formed due to the variation of the Coriolis parameter with latitude
Meanders, rings,eddies and gyres50°NWarmcorering00m40°NMeanderestColdcoreing30°Ngyre/80°W70°W60°W50°WFig.8.09A schematicillustrationof meandersintheGulfStreamandtheformationofrings,basedonRichardsonetal.(1978)andParker (1971)
Meanders, rings, eddies and gyres gyre