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.