Comparisons of the sea surface dynamic height variations in the Tsushima Strait in 2011 winter determined by tide gauges and the ferry-mounted GPS

Temporal variations of the sea surface dynamic height (SSDH) in 2011 winter are determined from tide gauge records at Pusan and Hakata by applying a tide-killer filter. The SSDH in the Tsushima Strait are also obtained by the GPS receiver mounted on the ferry “New Camellia” that crosses the Tsushima Strait almost every day. Generally, the tidal SSDH decreases in winter due to the cooling steric heights, but the SSDH at Pusan tends to increase in time with respect to that at Hakata, suggesting decrease of the eastward speed of the Tsushima current. This temporal tendency is also recognized in the GPS-determined SSDH; the long-term SSDH variations within the Tsushima Strait suggest that the eastward Tsushima current decreases both in the Eastern and Western Channel and that this tendency is clearer in the Eastern Channel