Fortnightly Variation of the Tsushima Warm Current on the Continental Shelf in the Southwestern Japan Sea.

The first and second branches of the Tsushima Warm Current flow on the continental shelf and along the shelf break/slope in the southwestern Japan Sea, respectively. The second branch corresponds to the offshore side of the bottom temperature front between the offshore cold and nearshore warm waters. Across the Tsushima Warm Current on the continental shelf and the shelf edge, five bottom‐mounted ADCPs with temperature sensors were deployed between middle June and late July 2014. At the shelf edge, the bottom temperature varied with the diurnal tidal cycle. The offshore bottom cold‐water intruded into the continental shelf region in conjunction with the fortnightly spring‐neap (2‐week) cycle which is the modulation of the diurnal K1 and O1 internal tides. The bottom temperature front and the first branch of the Tsushima Warm Current on the continental shelf intensified in response to the bottom cold‐water intrusion. Plain Language Summary: The path of Tsushima Warm Current and its variation, in the southwestern Japan Sea after passing through the Tsushima Straits, are not well understood because of the mesoscale eddy activities and the strong tidal currents. In this study, using the observational time series data of the current profiles and the bottom temperatures, we found that the Tsushima Warm Current on the continental shelf intensified about every 2 weeks. The velocity enhancement was caused by the short‐term variation and its modulation of the diurnal internal tides. Key Points: Fortnightly variation of the Tsushima Warm Current on continental shelfVariation of the Tsushima Warm Current locally controlled by internal tidesRelation between the Tsushima Warm Current and the bottom temperature front [ABSTRACT FROM AUTHOR]