| Acoustic measurements from two lines of moored acoustic Doppler current profilers (ADCPs) spanning the Tsushima Strait just north and south of Tsushima Island are used to estimate the seasonal flow and its vertical structure through the strait for the summer, autumn, and winter seasons of 1999–2000. In addition to the ADCP data, sea surface height (SSH) information from the TOPEX/POSEIDON satellite is included in the seasonal flow field estimations. A weighted least squares technique combines these two data sets with a system of dynamics that are governed by the linear, time-independent, shallow water equations. The solution weights are based on the expected errors to the dynamical equations and measurements. The forcing for the dynamics are wind stress and climatology, which are provided by the Navy Global Ocean and Atmospheric Prediction System (NOGAPS) and the Modular Ocean Data Assimilation System (MODAS) respectively. A conjugate gradient inverse method determines the flow field that best satisfies the weighted data and dynamics for each season.; The solutions, which are in terms of vertically integrated velocities and SSH/interface height, are computed using both a single-layered barotropic system of equations and a 2.5-layered baroclinic system of equations. Earlier studies show that the flow through the Tsushima Strait is barotropic throughout most of the year. The region just offshore of the southeast coast of South Korea, however, has been identified as being subject to strong baroclinic processes during the warmer seasons. In an attempt to verify this observation, errors in the dynamics of both the barotropic and baroclinic systems are computed. These errors reveal that the flow fields satisfy the dynamical equations to within the expected error throughout most of the domain. Within the region just offshore of the southeast coast of South Korea, however, the errors in the barotropic momentum equations exceed 3 times the expected error during autumn; therefore, implying that the barotropic approximation is not valid at this location. The errors in the baroclinic momentum equations are significantly reduced within this region during autumn, suggesting the existence of baroclinic processes. |
