EAS212 Lecture Notes - Lecture 14: Geostrophic Current, Pressure-Gradient Force, Ekman Transport
12 Mar 2018
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Eas lecture 14: geostrophic currents: ek(cid:373)a(cid:374) tra(cid:374)sport of surfa(cid:272)e (cid:449)ater (cid:272)a(cid:374) lead to it (cid:862)pili(cid:374)g up(cid:863) or (cid:862)(cid:271)ei(cid:374)g re(cid:373)o(cid:448)ed(cid:863) The current is set by the pressure gradients. Open ocean surface currents: surface currents initiated by ekman transport. Then maintained as geostrophic currents: generally, reach a few hundred metres deep, although some can reach 2000 m, one typical ocean unit of volume transport is sverdrup (sv, 1 sv = 106 m3 s-1. Water covered earth: the ekman transport is based on the large scale atmospheric circulation, this leads to bands of convergence and divergence. Divergence: ~ equator, 60 degrees: this generates large-scale geostrophic currents that would flow around the earth. Gyres: these circulation patterns are modified by the presence of land, at most latitudes, we get zonal currents within the ocean. In the south, a current can flow all around the world = antarctic circumpolar current.
