Characterization of high-frequency radar derived surface circulations in a semi-enclosed bay with an idealized model, the Yeosu bay, republic of Korea

Abstract

Surface circulation in the Yeosu Bay, Republic of Korea, is primarily characterized by time-mean currents, tidal currents, and residual currents based on hourly observations of O(1) km resolution maps of high-frequency radars-derived surface currents and sea surface heights from three tide gauges in the Yeosu bay and adjacent area for a period of two years (2010 to 2012). The time-mean currents field shows a southward flow up to 5 $cm s^{-1}$ at the channel and recirculates eastwards within bay mouth due to background currents (Tsushima warm currents). The tidal currents account for approximately 25% to 60% of total surface currents and are dominated by $M_2$ and $K_1$ frequency. The predominant along channel $M_2$ tidal currents are ranged from 10 to 25 $cm s^{-1}$ and $K_1$ tidal currents are dominated by cross channel currents which are ranged from 5 to 10 $cm s^{-1}$. The tidal currents exhibit polarized rotational tendency, in the channel and bay mouth, and rotate clockwise and counter clockwise, respectively. A series of idealized model experiments reveal that location of tide amphidromic point is dependent on topography and local pressure set up. Shorter the wave length, the tide amphidromic point approaches closer to the basin and show amplified tide and tidal currents. The funnel shape topography moves along channel and cross channel current amphidromic points to north and east of the bay, respectively, and induces polarized rotational tendency. Also, the baroclinic process are mainly exhibited at bay mouth area where the width is broad and generate uncorrelated lateral currents at the southwest of the bay.