The Japan Sea, known as the East Sea in Korea, has a steep bottom topography
(Fig. 1) that makes it a unique semi-enclosed ocean basin overlaid by a
pronounced monsoon surface wind. The Japan/East Sea, hereafter referred to as
JES, covers an area of 10
km
. It has a maximum depth in excess of
3,700 m, and is isolated from open oceans except for small (narrow and
shallow) straits, which connects the JES with the North Pacific through the
Tsushima/Korean and Tsugaru Straits and with the Okhotsk Sea through the Soya
and Tatar Straits. The JES contains three major basins called the Japan Basin
(JB), Ulleng/Tsushima Basin (UTB), and Yamato Basins (YB), and a high central
seamount called the Yamato Rise (YR). The JES has great scientific interest as
a miniature prototype ocean. Its basin-wide circulation pattern, boundary
currents, Subpolar Front (SPF), mesoscale eddy activities and deep water
formation are similar to those in a large ocean.
Numerical studies on the JES circulations started in early 1980. Various types of models were used such as the multi-layer model (Sekine, 1986, 1991; Kawabe, 1982b; Yoon, 1982a,b; Seung and Nam, 1992a,b; Seung and Kim, 1995), the Modular Ocean Model (MOM) (Kim and Yoon, 1994; Holloway et al., 1995; Kim and Yoon, 1996; Yoshikawa et al., 1999), rigid-lid z-level model (Yoshikawa et al., 1999), the Miami Isopycnal Coordinate Model (MICOM) (Seung and Kim, 1993) and the Princeton Ocean Model (POM) (Mooer and Kang, 1995; Chu et al., 1999c,d). Most of the numerical efforts are concentrated on simulating basin-wide circulation, the Tsushima Warm Current (TWC) bifurcation, and formation of the intermediate waters. However, there is lack of studies on dynamical mechanisms for the formation of seasonal variability of the JES circulation.
In this study, we use the POM to investigate driving mechanisms for the formation of the seasonal variabilities of the JES circulation including the subpolar front (SPF) meandering and eddies, the TWC bifurcation and its effect on the formation of mesoscale eddies in the UTB and the YB, and the Liman Cold Current (LCC) and its penetration into the southwestern waters along the Korean coast. The control run, forced by the climatological monthly wind stress, heat and fresh water fluxes, is designed to best simulate reality against which each experiment is compared. In the experiments, various external and internal factors are modified and the resulting circulation patterns and magnitudes compared to the control run results. Specifically, we estimate the contribution, in terms of volume transport and circulation patterns, of non-linear advection, wind forcing and lateral boundary transport to the ocean features identified in the control results. From this, we can estimate the relative importance of these factors to the seasonal variability of the JES circulation.