Theory question 203
Oceans and Lakes(a) Discuss, using specific examples, any four factors that determine the pattern of movement of ocean currents in the North Pacific Ocean (b) Select any one cold current in the North Pacific Ocean and outline its effects on the climate of the adjacent coastland
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(a) Planetary winds: NE trades drive the North Equatorial current westwards; westerlies drive the North Pacific Drift eastwards. Earth's rotation (Coriolis force) deflects currents to the right, giving a clockwise gyre (Kuroshio north, California current south). Shape of coastlines: Asia turns the current north as the Kuroshio; North America turns it south as the California current. Temperature and density differences: warm water moves poleward, cold water (Oyashio/Kamchatka) moves towards the equator. Salinity differences.
(b) e.g. California current: lowers coastal temperatures; winds over it are cooled so little rain falls (dry coast, Mexican/Californian desert); frequent fog along the coast (San Francisco); reduces the annual range. (Or Oyashio/Kamchatka current: cold, foggy coasts of north-east Asia and Japan, frozen harbours.)
Use named currents of the North Pacific only.