| Variations of current path of the Kuroshio in the southern region of Japan are summarized. The Kuroshio has three typical paths, the typical large-meander (tLM) path, the nearshore non-large-meander (nNLM) path, and the offshore NLM (oNLM) path, and takes them with a cycle such as nNLM → LM → oNLM. The NLM paths occurred during 1963-75 and from 1991 to the present, and the LM path occurred predominantly during 1953-63 and 1975-91; the variations between LM and NLM have a major periodicity of about 20 years. The Kuroshio in a NLM period takes nNLM and oNLM alternately, while a few or several events of LM occur in a LM-dominant period. The Kuroshio influences on coastal sea levels, and is characterized by the sea level difference (SLD) of Kushimoto minus Uragami, which are adjacent tide stations located just west and east of Cape Shiono-misaki around the center of the southern coast of Japan. The SLD is smallest for LM, a little larger for oNLM, and largest for nNLM. The region off Cape Shiono-misaki is a key place for the NLM path of the Kuroshio located close to the Japanese coast west of this cape. Two kinds of sharp spatial change occur south of the cape during the NLM periods: an increase of current velocity of the Kuroshio and descend of coastal sea level in the direction of the Kuroshio. This change is larger for nNLM than oNLM. The first key place for LM is the Tokara Strait south of Kyushu, where the Kuroshio axis is located north with small-amplitude meander during LM periods. The variation in location and shape of the Kuroshio in the Tokara Strait precedes the formation and decay of LM by about four months. In the LM formation process, a small meander of the Kuroshio propagates eastward and reaches Cape Shiono-misaki, where the second key place for LM, and the LM is formed. The LM formation may be due to an interaction between cold eddies, one is embraced by the small meander of the Kuroshio, and the other one exists in the Enshu-nada, the coastal region east of Cape Shiono-misaki. No interaction of eddies brings no formation of LM. When the interaction occurs, the LM may be formed, and its location and shape may depend on strength and way of the interaction. The last key place for all the typical paths of the Kuroshio is the Izu Ridge, which has two passages for the Kuroshio: the gap between Miyake-jima and Hachijo-jima and the deep region south of Hachijo-jima. The mid-depth path of the Kuroshio must pass either of these two passages; the tLM and nNLM paths pass the northern gap, and the oNLM path passes south of Hachijo-jima. |
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