TAILIEUCHUNG - BIOMES OF THE EARTH - OCEANS Phần 8

Tham khảo tài liệu 'biomes of the earth - oceans phần 8', ngoại ngữ, anh ngữ phổ thông phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | HISTORY AND EXPLORATION OF THE OCEANS 177 The submersible Alvin Alvin is a three-person submersible operated by the Woods Hole Oceanographic Institution and designed to dive to depths up to 14 765 feet 4 500 m . Launched in 1964 in 1966 it located a hydrogen bomb lost in the Mediterranean. In 1977 its crew discovered remarkable animal communities close to the Galápagos Islands at a depth of about 7 300 feet 2 225 m . In 1986 Alvin explored the wreck of the Titanic. Alvin is overhauled every three years when many of its parts are replaced and updated. Since 1964 the various versions of Alvin have accounted for more than 3 500 dives. In 2001-02 scientists and filmmakers fixed an IMAX-format movie camera in Alvin. The camera filmed the creatures at hydrothermal vents for the large-format feature film Voyage into the Abyss. Active sensors beam down radio waves that bounce off the sea surface and return to the satellite. The time it takes for the radio waves to return and the way they are scattered by the sea surface reveal information about height of sea level surface slope and surface roughness. This provides scientists with information on the size of sea waves the direction and strength of surface winds and the dips and bulges created by ocean currents. The sea surface also follows the rises and hollows on the seabed so mapping the sea surface can help scientists work out the contours of the seabed. In the 1990s . scientists Walter Smith and David Sandwell combined satellite data with existing data from depth soundings and sonar surveys to update maps of the ocean floor. Passive sensors mounted on oceanographic satellites detect temperature in the form of infrared radiation emitted from the sea surface and colors reflected naturally from the top few tens of yards of the water column. Browns reveal the presence of mud particles emptied into the sea from nearby rivers. Greens can show blooms of phytoplankton. Black can reveal oil spills. In many cases scientists .

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