| From June 1999 to June 2001, an array of the pressure-equipped inverted echo sounders was deployed to map the circulation in the southwestern Japan/East Sea. From the acoustic travel time data, the three-dimensional fields of temperature, potential density and specific volume anomaly were mapped daily, using Gravest Empirical Mode/Modular Ocean Data Assimilation System (GEM/MODAS)technique and optimal interpolation. CTD surveys from KORDI and URI at several months and locations determined the intermediate water (IW) properties in depths around 150-300 m. In this study, the observed variation between relatively fresh (<34.06) or salty (>34.06) IW is related to the preceeding record of mapped circulation on sigma-theta = 27.2. During 8/99-10/99 there were a strong northeastward current along the east coast of Korea and an anticyclonic circulation in the northeast UB. These currents contributed salty or fresh IW respectively to the western and eastern portions of a 10/99 CTD section along 37.75N. In 5/00 the North Korean Cold Current (NKCC) protruded far south to ~36N along the Korean coast, and a strong Ulleung Warm Eddy (UWE) persisted after having separated from the East Korean Warm Current (EKWC) five months earlier. A 5/00 CTD survey found fresh IW at all locations into which northern waters advected, and salty IW within the UWE. During 7/00- 9/00 the EKWC remained weak, cold fresh waters continued to fill the upper and intermediate UB from the north, and encircled the markedly weakening UWE from the east between Ulleung and Dok Islands. The 9/00 CTD survey found fresh IW throughout the UB, even within the UWE. During 3/01-6/01 the EKWC again began to contribute warm salty waters to the upper UB in a meander crest that extended north of 38N, but a steep cold trough of the subpolar front persisted in the eastern UB down to ~36.5N. The 6/01 CTD survey found that the IW layer remained fresh everywhere except in the southwest corner. |
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