Kuroshio Current(redirected from Black current)
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(Japan Current), a warm current in the Pacific Ocean along the southern and eastern shores of Japan. Deriving its name from the dark blue color of its water (in Japanese kuroshio means “black stream”), the current forms as a result of variations in water level in the northern part of the East China Sea and the adjacent ocean. Some scientists regard it as a continuation of the Northern Trade Winds Current after it passes through the straits between Taiwan and the southern Ryukyu Islands into the East China Sea.
The main Kuroshio Current enters the ocean through the northern straits of the Ryukyu Islands and flows as far as 36° N lat. and 150° E long., where it becomes the North Pacific Current. Branches of the Kuroshio Current generally extend to 40° N lat.; those flowing further north meet the cold Kuril Current and form numerous circulations. South of Shiono Misaki Cape (the southern tip of Honshu) the Kuroshio Current is about 170 km wide and 700 m deep. The flow of water here is 37.9 × 106 cu m per sec or about 73 cu km per hr. At 35° N lat. the depth of the current decreases to 200 m. The water temperature in August varies from 28°C in the south to 25°C in the north and in February from 18°C in the south to 12°C in the north. In the south the current moves at about 6 km per hr, and in the north its velocity is 1–2 km per hr.
There are significant variations in the location of the current. The northern branches extend to the periphery of the circulations—north of 41° N lat. in the summer and to 38°-39° N lat. in the winter. A typical feature is the meandering of the stream, associated with the formation of eddies on its borders. The annual temperature variation at Cape Shiono Misaki of almost 9°C at the surface is caused by the cold northwest winds. Along the eastern coast of Japan, between the Kuroshio Current and the mainland, there is a wall of cold water flowing from the north, as in the Gulf Stream. Like the Gulf Stream in the Atlantic Ocean, the Kuroshio Current forms a system of warm currents in the Pacific Ocean, which has a warming effect on the climate and hydrological conditions of the northern part of the ocean.