Warm water with an average yearly sea surface temperature exceeding 29 Åé exists in the tropical equatorial region. This body of water is called the warm pool and extends over an area 30 times larger than Japan. It is located in the equatorial zone between New Guinnea and the international date line. This warm pool is created by trade winds blowing from east to west.
The Kuroshio Current branches into the main stream and the Tsushima Current. The main current passes through the East China Sea and Tokara Islands and along the south coast of the Japanese archipelago, then turns north. The Tsushima Current passes through the Japan sea. The main current that goes north along the Japanese archipelago's Pacific Coast converges with the Oyashio Current that originates in the Bering Sea. It causes an explosive growth of the April plankton, creating rich fishing grounds.
From ancient times, the Kuroshio Current has, for Japan, been not only a fishing resource but has also been a sea transportation route and moderator of a mild climate. At present, intensive international ocean observation and Earth observation by satellites are being conducted. It will be important to know the role of Kuroshio Current in detail in order to determine the mechanism of global-scale climate change.