Journal of Oceanography, Vol. 63 (No. 5), pp. 849-862, 2007
Hiroshi Kuroda1*, Manabu Shimizu1, Yuuichi Hirota2 and Hideki Akiyama1
1National Research Institute of Fisheries Science, Fukuura, Kanazawa, Yokohama, Kanagawa 236-8648, Japan
2National Research Institute of Fisheries Science, Sanbashi-dori, Kochi 780-8010, Japan
(Received 29 November 2006; in revised form 3 April 2007; accepted 21 May 2007)
Abstract: Through analysis of monthly in situ hydrographic, tide gauge, altimetry and Kuroshio axis data for the years 1993-2001, the intraannual variability of sea level around Tosa Bay, Japan, with periods of 2-12 months is examined together with the intraannual variability of the Kuroshio south of the bay. It is shown that the intraannual variation of steric height on the slope in Tosa Bay can account for that of sea level at the coast around the bay as well as on this slope. It is found that the steric height (or sea level) variation on the slope in this bay is mainly controlled by the subsurface thermal variation correlated with the Kuroshio variation off Cape Ashizuri, the western edge of Tosa Bay. That is, when the nearshore Kuroshio velocity south of the cape is intensified [weakened] concurrently with the northward [southward] displacement of the current axis, temperature in an entire water column decreases [increases] simultaneously, mainly due to the upward [downward] displacement of isotherms, coincident with that of the main thermocline. It follows that the steric height (or sea level) decreases [increases].