Surface tidal and residual circulations in an enclosed bay

Abstract

This paper examines surface tidal and residual circulations in an enclosed bay, Yeosu Bay off the southern coast of Korea using observations of hourly high-frequency radar(HFR)-derived surface current maps on a spatial resolution of 1 km and hourly records of the local sea surface height and wind for a period of two years (2015 to 2016) and analytic solutions obtained from an idealized tidal model. The phase structure of the semi-diurnal ($M_{2}$) surface currents is more homogeneous and uniform than that of the diurnal ($K_{1}$) surface currents, and the variance ratios of residual surface currents in the semi-diurnal frequency band [$1.91 \leq \sigma \leq 1.95$ cycles per day (cpd)] are approximately 50$\%$ less than those of residuals in the diurnal frequency band ($0.98 \leq \sigma \leq 1.02$ cpd) including $P_{1}$, $S_{1}$, and $K_{1}$ tidal constituents. These two characteristics may indicate that the regional surface circulation is more barotropic at the semi-diurnal frequency and more baroclinic at the diurnal frequency.