- 行业: Weather
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The American Meteorological Society promotes the development and dissemination of information and education on the atmospheric and related oceanic and hydrologic sciences and the advancement of their professional applications. Founded in 1919, AMS has a membership of more than 14,000 professionals, ...
The eastward current that forms the northern part of the North Pacific subtropical gyre. It originates from the Kuroshio Extension east of the Emperor Seamounts (170°W) and maintains the Arctic Polar Front with the Aleutian or Pacific Subarctic Current, with which it experiences much mixing as it proceeds eastward. A broad band of flow some 2000 km wide, it feeds its water into the California Current on approaching the North American coast.
Industry:Weather
A southward flowing current along the northern Korean coast fed from the Liman Current. At 37°–38°N it meets the East Korean Warm Current to establish the Arctic Polar Front of the Japan Sea. It is the source of the Mid-Japan Sea Cold Current, which withdraws water from it along its way to reinforce the polar front across the entire length of the Japan Sea.
Industry:Weather
The broad region of uniform westward flow that forms the southern part of the Northern Hemisphere subtropical gyres driven by the trade winds. Being directly wind driven, the NEC responds quickly to variations in the wind field and is therefore strongest in winter (February). In the Atlantic Ocean it is found between 8° and 30°N with speeds of 0. 1–0. 3 m s<sup>−1</sup>. In the Pacific Ocean it has similar speed but is limited to 8°–20°N. In the Indian Ocean it exists only during December–April when the northeast monsoon produces the same wind forcing as the Northern Hemisphere trade winds. It then runs as a narrow current of 0. 3 m s<sup>−1</sup> from Malacca Strait to Sri Lanka where it bends southward and accelerates in the region 60°–75°E to 0. 5–0. 8 m s<sup>−1</sup> between 2°S and 5°N and continues along the equator.
Industry:Weather
A band of eastward flow between the westward flowing North and South Equatorial Currents. The location and strength of the NECC is determined by the intertropical convergence zone (ITCZ) of the atmosphere. In the Pacific Ocean it is strongest in May–January when it flows between 5° and 10°N with 0. 4–0. 6 m s<sup>−1</sup>; in February–April it is restricted to 4°–6°N with speeds below 0. 2 m s<sup>−1</sup> and disappears east of 110°W. In the Atlantic Ocean the NECC is observed between 5° and 10°N with speeds of 0. 1–0. 3 m s<sup>−1</sup>; it is strongest during August when it flows from South America into the Gulf of Guinea and weakest in February when it is restricted to the region east of 20°W. In the Indian Ocean the NECC exists during the northeast monsoon season only and is then the only countercurrent; it is therefore mostly called the Equatorial Countercurrent. It is centered on 5°S, again the location of the ITCZ.
Industry:Weather
One of the western boundary currents of the Atlantic Ocean and part of the pathway for water from the Southern into the Northern Hemisphere in the global ocean conveyor belt. Flowing northward along the coast of northern Brazil with speeds up to 0. 8 m s<sup>−1</sup>, it originates from the South Equatorial Current and continues as the Guyana Current.
Industry:Weather
A water mass found in the Atlantic at depths between 1000 and 4000 m that can be traced from there into most other ocean basins. It is formed in the North Atlantic from some 5 Sv (5 × 10<sup>6</sup> m<sup>3</sup>s<sup>−1</sup>) of Atlantic Bottom Water entering through Denmark Strait and across the Scotland–Faeroe–Iceland Ridge. This water flows toward the Labrador Sea, entraining another 5 Sv from the eastern North Atlantic on its way. Another 5 Sv is added in the Labrador Sea by winter convection, giving a total of 15 Sv of NADW formation. The NADW formation process is the engine of the ocean conveyor belt, which makes NADW one of the most important water masses for today's climate.
Industry:Weather
The eastward flowing current that originates from the Gulf Stream Extension east of the Grand Banks (about 40°N, 50°W). It initially forms part of the Atlantic subtropical gyre but separates from it after less than 500 km near 45°W, turning northeastward and following the Arctic Polar Front, also known as the North Wall, with a transport of some 30 Sv (30 × 10<sup>6</sup> m<sup>3</sup>s<sup>−1</sup>). Some of this water enters the subpolar gyre through mixing across the polar front and feeds the Irminger Current, but most of it is delivered to the Norwegian Current. The North Atlantic Current carries warm subtropical water much farther north than any other current of the Northern Hemisphere. As a result the climate of northern Europe is much milder than the climate of Alaska or northern Siberia, both of which are located at comparable latitude.
Industry:Weather
The relatively weak general area of high pressure that, as shown on mean charts of sea level pressure, covers most of North America during winter. This pressure system is not nearly as well-defined as the analogous Siberian high.
Industry:Weather
A theorem in psychrometry that states that the dewpoint temperature is always less than or equal to the wet-bulb temperature, which is always less than or equal to the dry-bulb temperature. It is not, however, true in supersaturated air or for air temperatures below freezing if the wet bulb is frozen and the air is supersaturated with respect to ice.
Industry:Weather
The line connecting all places at which the mean temperature (°C) of the warmest month is equal to 9 − 0. 1''k'', where ''k'' is the mean temperature of the coldest month. (In degrees Fahrenheit the relationship becomes 51. 4 − 0. 1''k''. )
This line fits the arctic tree line better than any other purely climatic isopleth hitherto tried.
Industry:Weather
