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Pad 100%- HW4 SnowballEarth Circulation.docx You can zoom in or out using the +/- icons in the top right 10. Identify three regions on Earth that have particularly strong ocean currents. Use words (e.g. northern/southern, eastern/western, tropical/polar, coastal, etc.) to describe the locations, not latitude/longitude 11. Hong Kong is on the southern coast of China and is a major shipping port, with many cargo ships heading for the Panama Canal. Looking at the map of ocean currents, should container ships travelling from Hong Kong to the Panama Canal sail across the North Pacific or the Equatorial Pacific? Now look at ocean temperatures clicking on Sea temperature in the right-hand menu 12. Ocean water, like most things on earth, tends to be warmer near the equator and cooler at higher latitudes. Identify two places on Earth where there are strong ocean currents bringing warm water into a cooler region Open With PrintExplanation / Answer
10/12 Maps of the general circulation at the sea surface were originally constructed from a vast amount of data obtained from inspecting the residual drift of ships after course direction and speed are accounted for in a process called dead reckoning. This information is collected by satellite-tracked surface drifters at sea at present. The pattern is nearly entirely that of wind-driven circulation.
At the surface, aspects of wind-driven circulation cause the gyres (large anticyclonic current cells that spiral about a central point) to displace their centres westward, forming strong western boundary currents against the eastern coasts of the continents, such as the Gulf Stream–North Atlantic–Norway Current in the Atlantic Ocean and the Kuroshio–North Pacific Current in the Pacific Ocean. In the Southern Hemisphere the counterclockwise circulation of the gyres creates strong eastern boundary currents against the western coasts of continents, such as the Peru (Humboldt) Current off South America, the Benguela Current off western Africa, and the Western Australia Current. The Southern Hemisphere currents are also influenced by the powerful, eastward-flowing, circumpolar Antarctic Current. It is a very deep, cold, and relatively slow current, but it carries a vast mass of water, about twice the volume of the Gulf Stream. The Peru and Benguela currents draw water from this Antarctic current and, hence, are cold. The Northern Hemisphere lacks continuous open water bordering the Arctic and so has no corresponding powerful circumpolar current, but there are small cold currents flowing south through the Bering Strait to form the Oyaand Anadyr currents off eastern Russia and the California Current off western North America; others flow south around Greenland to form the cold Labrador and East Greenland currents. The Kuroshio–North Pacific and Gulf Stream–North Atlantic–Norway currents move warmer water into the Arctic Ocean via the Bering, Cape, and West Spitsbergencurrents.
In the tropics the great clockwise and counterclockwise gyres flow westward as the Pacific North and South Equatorial currents, Atlantic North and South Equatorial currents, and the Indian South Equatorial Current. Because of the alternating monsoon climate of the northern Indian Ocean, the current in the northern Indian Ocean and the Arabian Sea alternates. Between these massive currents are narrow eastward-flowing countercurrents.
Other smaller current systems found in certain enclosed seas or ocean areas are less affected by wind-driven circulation and more influenced by the direction of water inflow. Such currents are found in the Tasmanian Sea, where the southward-flowing East Australian Currentgenerates counterclockwise circulation, in the northwestern Pacific, where the eastward-flowing Kuroshio–North Pacific current causes counterclockwise circulation in the Alaska Current and Aleutian Current(or Subarctic Current), in the Bay of Bengal, and in the Arabian Sea.
Deep-ocean circulation consists mainly of thermohaline circulation. The currents are inferred from the distribution of seawater properties, which trace the spreading of specific water masses. The distribution of density is also used to estimate the deep currents. Direct observations of subsurface currents are made by deploying current meters from bottom-anchored moorings and by setting out neutral buoyant instruments whose drift at depth is tracked acoustically.
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