Behavior of Diurnal Internal Waves in the Southwestern East/Japan Sea

Chae, J.-Y.; Jeon, C.; Park, S.J.; Choi, Y., and Park, J.-H., 2018. Behavior of diurnal internal waves in the southern East/Japan Sea. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 486–490. Coconut Creek (Florida), ISSN 0749-0208. The diurnal internal waves cannot freely propagate and are trapped near their generation site in the East/Japan Sea due to its sub-inertial environment. Previous studies show that diurnal internal shelf waves (ISWs) are generated around the southern Ulleung Basin (UB) with their energy concentrated there. To investigate the spatio-temporal variation of diurnal ISWs, we use a high-resolution numerical ocean model that is forced by realistic 16 tidal constituents and involves a data assimilation scheme. The baroclinic total energy and the conversion rate of barotropic to baroclinic energy show higher values at the southern side of the UB, showing features of ISWs by dominant eastward energy flux and bottom trapped current mode. The regionally-integrated conversion rate and total energy in the vicinity of the generation site fluctuate at about 6-month period. Changes in the stratification and barotropic forcing are examined to understand the semi-annual variation in the ISW field. A parameter showing the relative impact of stratification and water column stretching reveals that the latter predominates both the ISWs generation and horizontal distribution. The diurnal tidal transport change reveals a consistent variation with the conversion rate, supporting that the changes in the barotropic forcing in the Korea Strait can induce semi-annual variation of diurnal ISWs over the southern UB.