- 行业: Education
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Founded in 1876, Texas A&M University is a U.S. public and comprehensive university offering a wide variety of academic programs far beyond its original label of agricultural and mechanical trainings. It is one of the few institutions holding triple federal designations as a land-, sea- and ...
The western boundary current in the Indian Ocean south of 30°S. The southern Agulhas Current flows southwestward as a narrow jet along a steep continental slope, and is normally pinned to within 10-15 km of its mean position at latitudes 28. 5-34°S. Large meanders - called the Natal pulse - can sometimes occur within this region. These extend an average of 170 km offshore with downstream propagation rates of about 21 cm s<sup>-1</sup>, with the rates decreasing to 5 cm s<sup>-1</sup> as the continental shelf broadens near 34°S. At this point the current separates from the coast and continues southwestward along the Agulhas Bank, where many meanders, plumes and eddies exist. The maximum transport of the Agulhas occurs in the vicinity of Agulhas Bank, where transport estimates range from 95 to 136 Sv. The core of the current has been defined as where surface velocities exceed 100 cm s<sup>-1</sup>, with the core averaging about 34 km wide with a mean peak speed of 136 cm s<sup>-1</sup> (with a greatest peak speed of 245 cm s<sup>-1</sup>).
At around 36°S the Agulhas leaves the continental shelf and develops oscillations of increasing amplitude, eventually retroflecting back toward the Indian Ocean in the region of 16-20°E as the Agulhas Return Current. The retroflection loop usually encloses a pool of Indian Ocean surface water south of Africa whose temperature is more than 5° warmer than South Atlantic surface water at similar latitudes. The core of the Return Current infrequently passes over the Agulhas Plateau.
Industry:Earth science
A 1991-1992 experiment involving a tomography array located between Puerto Rico and Bermuda. The width of the array was abouata 670 km and is consisted of six mooring acoustic sources and receivers. The array detected signals of the lowest internal wave modes at diurnal frequencies.
Industry:Earth science
Term used to describe the part of the deep sea thought lifeless in the mid-19th century. It was thought that the abyss was filled with a thick layer of 4° C (since sea water was thought to be densest at that temperature), motionless water which, combined with the tremendous pressures and absence of sunlight, virtually guaranteed an absence of life. The term was coined by the naturalist Edward Forbes in the 1840s who, after dredging for life forms in various regions, postulated eight bands or depth zones, each characterized by a particular assemblage of animals. These zones extended to a lower limit he set at about 300 fathoms below which the existence of life was highly unlikely. His results (and therefore perceptions) on this issue were skewed by an 1841 cruise in the eastern Mediterranean where he dredged for life forms at depths up to 230 fathoms in what is now known to be a relatively barren area. The contrast of this with the rich hauls he made in shallower waters around England led to his thinking the abyss devoid of life.
Industry:Earth science
A project whose long-term goals are to create and demonstrate a reactive survey system capable of long-term unattended deployments in harsh environments. The scientific objectives include:
* to create small, high performance mobile platforms capable of deployments lasting for several months, with both propellor-driven, fast survey vehicles and buoyancy-driven glider vehicles being developed;
* to create an infrastructure that supports controlling, recovering data from, and managing the energy of remote deployed mobile platforms, with structure elements including moorings, docking stations, acoustic communications, two-way satellite communcations, and the Internet;
* to demonstrate these capabilities in science-driven field experiments; and
* to develop adaptive sampling strategies to most efficiently meet deployment objectives.
Industry:Earth science
A water mass traditionally defined as any water with salinity greater than 35. 0 entering the arctic domain from the Atlantic domain. AW first entering the Iceland and Norwegian Seas typically has temperatures of 6-8° C and a salinity range of about 35. 1-35. 3, although the property ranges of other waters obviously connected with AW have prompted some to expand the definition to include all waters warmer than 3° C and more saline than 34. 9. Estimates of the total influx of AW range as high as 9 Sv.
Industry:Earth science
A project that took place Feb. 23 through Apr. 10, 1974 and investigated small-scale meteorological and oceanographic processes associated with leads in pack ice near Barrow, Alaska. The experiment plan called for rapid deployment of five instrumental huts, measuring equipment and personnel by helicopeters and fixed-wing aircraft. The processes of primary interest were sensible, latent, and radiant heat loss to the atmosphere as well as the sinking of convective plumes of saline water formed by freezing and brine rejection at the surface. Logistical problems limited the success of the experiment, with the helicopter range limiting deployment to within 30 miles of Barrow and a dearth of suitable leads in that area.
Industry:Earth science
A stationary point around which tides rotate in a counterclockwise (clockwise) sense in the northern (southern) hemisphere, i.e. the point about which the cotidal lines radiate. The vertical range of the tide increases with distance away from the amphidrome, with the amphidrome itself the spot where the tide vanishes to zero (or almost zero). This is also called an amphidromic point.
Industry:Earth science
A program composed of two complementary enviromental initiatives: (1) to gather information about temperatures in the ocean using acoustic tomography to verify the predictions of existing climate models; and (2) to assess the potential effects of low frequency sound transmissions on marine mammals and sea turtles through its MMRP component.
Industry:Earth science
A center of action centered near the Azores Islands (near 35° N and 25° W). It extends from near the western end of the Mediterranean Sea westward almost to Florida in the summer months, with the western section in summer sometimes referred to as the Bermuda High.
Industry:Earth science
An IGAC activity. The scientific goals of APARE are to quantify the oxidising efficiency, and atmospheric acidification by studying the emission, transport, chemical transformation, and deposition of primary and secondary chemical species over the East Asian Continental Rim Region and northwestern Pacific Ocean. The objectives are:
* to assess transport and chemical transformations of air pollutants over the East-Asian continent and the northwestern Pacific Ocean, with particular emphasis on distribution and photochemistry of reactive species to understand oxidizing efficiency and the 03 budget in the region; and
* to determine the deposition of primary and secondary pollutants in the East Asian region, with major emphasis on understanding the present status and future prospects of acidification of the atmosphere and deposition of acidic species in the region.
Industry:Earth science
