1. The ocean currents exercise

2. Ocean surface currents can be Ocean surface currents are driven by Warm (and fast) or Cold (and sluggish) Westward flow of equatorial surface wind Earth’s rotation Gravitational roll-back of the waters that equatorial surface wind stacks on the western margins of tropical/semitropical oceans.

3. The westward flow of equatorial surface wind produces anticyclonic current gyres. 1 2 3 4 54 3 They start with North Equatorial and South Equa- torial currents, in the Atlantic (1, 2), Pacific (3, 4) and Indian (only 5) oceans. Warm Cold 1 North Equatorial Current in the Atlantic Ocean 2 South Equatorial Current in the Atlantic Ocean 3 North Equatorial Current in the Pacific Ocean 4 South Equatorial Current in the Pacific Ocean 5 South Equatorial Current in the Indian Ocean Why no North Equatorial Current in the Indian Ocean?

4. The westward flow of equatorial surface wind produces anticyclonic current gyres. 1 2 3 4 5 4 3 Warm Cold 6 Kuroshio or Japan Current 7 East Australian Current 8 Gulf Stream 9 Brazil Current 10 Agulhas Current Blocked by land, these currents turn polewards. 6 8 9 7 10

5. The westward flow of equatorial surface wind produces anticyclonic current gyres. Warm Cold 11 California Current 12 Peru Current 13 Canary Current 14 Benguela Current 15 West Auatralian Current They cool down as they reach ~45°, and return as cold water currents 1 2 3 4 5 4 3 6 8 9 7 10 14 12 11 13 15

6. Earth’s rotation produces the Circum-Antarctic or Circum-Polar Current. Warm Cold Also called the West Wind Drift, this cold water current is the only ocean surface current that joins the waters of all the oceans. 1 2 3 4 5 4 3 6 8 9 7 10 14 12 11 13 15 Circum-Antarctic Circulation

7. Warm Cold Equatorial Counter Current is the gravity driven roll-back of warm waters stacked on western margins of the tropical ocean by westward flowing equatorial surface wind. 1 2 3 4 5 4 3 6 8 9 7 10 14 12 11 13 15 Circum-Antarctic Circulation ECC

8. Warm Cold A bottle dropped by Scripps off Perth, Australia, took 5 years to reach Miami, Florida, located about 26,000 km away. 1 2 3 4 5 4 3 6 8 9 7 10 14 12 11 13 15 Circum-Antarctic Circulation ECC What currents did it ride on? What was its average speed?