A 　Role　for　Ferry　Based 　Monitoring　in　East　Asian　Marginal　Seas

Characteristics of the current structure and seasonal variations of the Tsushima Warm Current through the Tsushima Straits are estimated using ADCP data from ferry based monitoring. Volume transport through the Tsushima Straits, averaged from February 1997 to July 2005, is 2.6 Sv (Sv identical with 10 super(6) m super(3)s super(-1)) and those of the eastern and western channels are 1.1 and 1.5 Sv, respectively. Volume transport has strong seasonal variations with two maxima from spring to autumn (double peaks). Variations of the volume transport over the past few decades are estimated using the relationship between the volume transport and the sea level difference across the Tsushima Straits. The velocities and volume transports obtained by the ferry based monitoring have been applied to validations and as boundary conditions of numerical models for Pacific and Japan Sea circulations, and for Japan Sea forecasts based on data assimilation. As in the Tsushima Straits, ferry based monitoring using frequently operated routes around the east Asian marginal seas will be a powerful means to monitor future environmental changes such as global warming in the east Asian region.