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The Indian Ocean


Besides the Pacific and the Atlantic Oceans, the Indian Ocean is the third largest body of water in the World. The Ocean is bounded in the north by southern Asia, in the west by the Arabian Peninsula and Africa, in the east by the Malay Peninsula, the Sunda Islands, and Australia, and in the south by the South Polar Ocean. The Indian Ocean is separated from the Atlantic Ocean by the 20 degree east meridian south of Africa, and from the Pacific by the 147 degree east meridian south of Australia. The northernmost extent of the Indian Ocean is approximately 30 degree north latitude in the Persian Gulf.



Using a collection of satellite-based observations, scientists and visualizers stitched together months of observations of the land surface, oceans, sea ice, and clouds into a seamless, true-color mosaic of every square kilometer (.386 square mile) of our planet. (The Blue Marble)

The Continental plates


The African, Indian, and Antarctic continental plates of the earth’s surface meet in the Indian Ocean. This triple-junction (Y-form plate boundary) is marked by different branches of the Mid-Ocean Ridge System - a submarine mountain range with the Central Indian Ridge running southward from the edge of the continental shelf near the Arabian Sea, the Southwestern and Southeastern Indian Ridge, and the Ninetyeast Ridge. The eastern, western, and southern ocean basins thus formed are subdivided into smaller basins by additional ridges.



The Indian Ocean climate


The Indian Ocean climate north of the equator is strongly influenced by the Monsoon wind system. From October to April, strong northeast winds blow; from May until October south and west winds prevail. In the Arabian Sea, the violent monsoon brings heavy rain to the Indian subcontinent. When the monsoon winds change, cyclones sometimes strike the shores of the Arabian Sea. In the Southern Hemisphere the winds generally are weaker, but summer storms near Mauritius can be severe.



Packing sustained winds of 80 miles (128 km) per hour, with gusts of up to 97 miles (157 km) per hour, Cyclone Crystal was approaching the island of Mauritius in the western Indian Ocean on December 26, 2002. (Photo: Jacques Descloitres, MODIS)

Recently, scientists have identified the climatic kin of the Pacific El Niño phenomenon in the Indian Ocean, where it caused widespread weather problems in 1997. The scientists found that water temperatures along the equatorial Indian Ocean have a habit of flip-flopping. Usually, warm water accumulates in the eastern part of the ocean near Indonesia, while the western section near Africa remains relatively cool. However, this pattern can occasionally reverse, when winds and ocean currents chill the eastern Indian Ocean. As a consequence, the western Indian Ocean warms dramatically bringing devastating rains to Kenya and neighboring countries. The shift enhanced the temperature disparity feeding the growth of storms over East Africa and fostering record drought and fires in Indonesia.


The Indian Ocean currents are widely controlled by the monsoon. Two large circular currents, one in the Northern Hemisphere flowing clockwise and one south of the equator moving counter clockwise, constitute the dominant flow pattern. During the winter monsoon, however, currents in the north of the Indian Ocean are reversed.


Highest surface water salinity occurs in the Arabian Sea and in a belt between southern Africa and southwestern Australia. The average northern limit of icebergs is 45 degree south latitude.





The earliest known civilizations in the valleys of the Euphrates, Tigris, and Indus rivers and in Southeast Asia have developed near the Indian Ocean. During Egypt's 1st dynasty (3000 B.C.), sailors were sent out onto its waters, journeying to Punt, which was part of present-day Somalia. Returning ships brought gold and slaves. Phoenicians of the 3rd millennium B.C. may have entered the area, but no settlements resulted.


Marco Polo (1254-1324) is thought to have returned from the Far East passing through the Strait of Malacca. Vasco da Gama rounded the Cape of Good Hope in 1497 and sailed to India, the first European to do so. Portugal attempted to achieve dominance for more than a century but was thwarted in the mid-1600s. The Dutch East India Company (1602-1798) sought control of trade with the East across the Indian Ocean. France and Britain established trade companies for the area, but Britain became the principal power. After 1815 it dominated the area.



Fisheries in the Indian ocean: Encircling the school of tuna is now complete. The workboat is bringing the end of the net back to the ship so that hauling in can proceed. (Photo: Jose Cort)



The Indian Ocean’s strategic importance far outweighs the economic value of its minerals or marine life. Accordingly, the warmth of the Indian Ocean keeps primary production low except for a few sites scattered over the ocean. Life in the Indian Ocean is thus limited. However, its fish species are of great and growing importance to the bordering countries for domestic consumption and export. Fishing fleets from Russia, Japan, South Korea, and Taiwan exploit the Indian Ocean mainly for shrimp and tuna. Endangered marine species include the dugong, seals, turtles, and whales; oil pollution mainly occurs in the Arabian Sea, Persian Gulf, and Red Sea.



Offshore deep bedrocks


Large occurrences of hydrocarbons are being trapped in the offshore deep bedrocks of Saudi Arabia, Iran, India, and western Australia. Roughly 40% of the world's offshore oil production comes from the Indian Ocean. Beach sands rich in heavy minerals, offshore placer deposits and deep sea polymetallic nodules are actively exploited by bordering countries, particularly India, South Africa, Indonesia, Sri Lanka, and Thailand.


The opening of the Suez Canal in 1869 revived the European interest in the East, but no nation was successful in establishing trade dominance. The 163 km long and at minimum 60 m wide Suez canal connects the Mediterranean Sea and the Red Sea and is extensively used by modern ships. Taxes paid by the vessel owners represent an important source of income for the Egyptian government. The canal is cutting through three lakes: the Lake Manzala in the north, the Lake Timsah in the middle, and the Bitter Lakes further south. The Bitter Lakes makes up almost 30 km of the total length.



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