CSIR NET June 2016 Q41: Physical Oceanography
Ocean currents can be classified by temperature and origin: cold currents typically flow along eastern ocean boundaries (equatorward, driven by upwelling of cold deep water) or form part of large-scale wind-driven circulation like the Antarctic Circumpolar Current, while warm currents typically flow along western ocean boundaries (poleward, carrying warm tropical water to higher latitudes).
The Circumpolar Current (Antarctic Circumpolar Current), the California Current, and the Peru (Humboldt) Current are all cold currents — the Circumpolar Current continuously circulates cold Southern Ocean water around Antarctica, while the California and Peru Currents are cold, eastern-boundary currents that bring cold, often upwelling-enriched water equatorward along the west coasts of North and South America respectively.
The Agulhas Current, by contrast, is a warm, western-boundary current that transports warm water poleward along the southeastern coast of Africa, from the Indian Ocean tropics toward higher latitudes — making it thermally and dynamically distinct from the other three cold currents.
The Agulhas Current, by contrast, is a warm, western-boundary current that transports warm water poleward along the southeastern coast of Africa, from the Indian Ocean tropics toward higher latitudes — making it thermally and dynamically distinct from the other three cold currents.
Option 1 (Circumpolar current) is a cold current, grouping with the other cold currents rather than standing apart.
Option 2 (California current) is a cold, eastern-boundary current, consistent with the other cold currents.
Option 3 (Agulhas current) is correct — it is a warm, western-boundary current, unlike the other three, which are all cold currents.
Option 4 (Peru current) is also a cold, eastern-boundary current, grouping with California and Circumpolar rather than standing apart.
Option 2 (California current) is a cold, eastern-boundary current, consistent with the other cold currents.
Option 3 (Agulhas current) is correct — it is a warm, western-boundary current, unlike the other three, which are all cold currents.
Option 4 (Peru current) is also a cold, eastern-boundary current, grouping with California and Circumpolar rather than standing apart.