Inertial oscillations in the Korea Strait

Inertial oscillations (IO) are examined in the Korea Strait based on measur ements from 13 acoustic Doppler current profilers covering the time period May 1999 through March 2000. Strong IO responses to wind stress occur durin g summer. A simple linear model predicts that winter wind stress is expecte d to generate inertial responses of the same order of magnitude as those in summer. However, the observed winter IO response is much weaker than predi cted. During summer, the currents within the mixed layer and below the mixe d layer are of comparable amplitude but in opposite directions. The depth a t which the currents reverse directions varies throughout the year as the m ixed layer deepens from about 40 m during summer to the bottom of the water column in November. During winter, the velocity structure is more uniform in depth with currents in the same direction throughout the water column. O ne possible explanation for these phenomena is related to the combined effe ct of the strait boundaries and the strong summer stratification. The strat ification prevents the wind stress momentum flux from mixing downward below the thermocline and thus allows the development of a bottom current separa te from the surface current. Such a velocity structure is necessary to sati sfy the no-flow condition through the land boundaries.