Spatial and Temporal Variations of Anti-clockwise Eddy Formed in the Eastern Channel of the Tsushima Strait

HF radar measurement in the Tsushima Strait reveals frequent appearance of anti-clockwise eddy in an eastern channel of the Tsushima Strait. In this study, spatial and temporal variations of this anti-clockwise eddy are investigated. The eddy generally appears from the southern part of the eastern coast of Tsushima Island and is shed to the northeast by the Tsushima Warm Current (TWC). Three modes (4～6, 10～12, and more than 30 days) are found in frequency distribution of eddy formation intervals. Location of the eddy and the highest mode of the eddy formation interval suggest that the eddy is lee-side eddy formed behind Tsushima Island by the incoming TWC. Second mode indicates that the eddy formation is affected by variations of intensities of TWC and tidal currents. The third mode corresponds to seasonal variation of the eddy generation, which is probably caused by a seasonal variation of vertical structure of TWC