• Journal of the korean society of oceanography
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• v.39 no.2
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• pp.119-135
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• 2004

A three-dimensional numerical model using POM (the Princeton Ocean Model) is established in order to understand the dispersion processes of the Yangtze River water in the Yellow and East China Seas. The circulation experiments for the seas are conducted first, and then on the bases of the results the dispersion experiments for the river water are executed. For the experiments, we focus on the tide effects and wind effects on the processes. Four cases of systematic experiments are conducted. They comprise the followings: a reference case with no tide and no wind, of tide only, of wind only, and of both tide and wind. Throughout this study, monthly mean values are used for the Kuroshio Current input in the southern boundary of the model domain, for the transport through the Korea Strait, for the river discharge, for the sea surface wind, and for the heat exchange rate across the air-sea interface. From the experiments, we obtained the following results. The circulation of the seas in winter is dependent on the very strong monsoon wind as several previous studies reported. The wintertime dispersion of the Yangtze River water follows the circulation pattern flowing southward along the east coast of China due to the strong monsoon wind. Some observed salinity distributions support these calculation results. In summertime, generally, low-salinity water from the river tends to spread southward and eastward as a result of energetic vertical mixing processes due to the strong tidal current, and to spread more eastward due to the southerly wind. The tide effect for the circulation and dispersion of the river water near the river mouth is a dominant factor, but the southerly wind is still also a considerable factor. Due to both effects, two major flow directions appear near the river mouth. One of them is a northern branch flow in the northeast area of the river mouth moving eastward mainly due to the weakened southerly wind. The other is a southern branch flow directed toward the southeastern area off the river mouth mostly caused by tide and wind effects. In this case, however, the tide effect is more dominant than the wind effect. The distribution of the low salinity water follows the circulation pattern fairly well.

• Ocean and Polar Research
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• v.34 no.3
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• pp.337-348
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• 2012

This study investigates the effects of tide, wind and oceanic currents on oil spill dispersions through a series of numerical floats tracking experiments on the Sea Prince oil spill incident occurred in 1995 using a 3-dimensional high resolution ocean circulation model. For that, a total of four experimental cases (experiment with tide, wind and oceanic currents, experiment with tide and oceanic currents, experiment with wind and oceanic currents, and experiment with tide and wind) were compared. It could be seen that results from experiment involving all external forces showed better agreement with the observed pattern of oil slick movement than other cases. The oceanic currents acted to drive floats to move to the western channel of the Korea straits and wind accelerated the eastward movement of floats in the early stage of the incident. Tidal currents played significant role in the horizontal dispersion of floats.

• Ocean and Polar Research
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• v.25 no.spc3
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• pp.361-371
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• 2003

The effect of bottom friction on the steady wind-driven circulation in the Yellow Sea and the East China Sea (YSECS) has been studied using a two-dimensional numerical model with and without tidal forcing. Upwind flow experiment in YSECS has also been carried out with a schematic time variation in the wind field. The surface water setup and circulation pattern due to steady wind forcing are found to be very sensitive to the bottom friction. When the effects of tidal currents are neglected, the overall current velocities are overestimated and eddies of various sizes appear, upwind flow is formed within the deep trough of the Yellow Sea, forming a part of the topographic gyre on the side of Korea. When tidal forcing is taken into account, the wind-induced surface elevations are smoothed out due to the strong tide-induced bottom friction, which is aligned almost normal to the wind stresses; weak upwind flow is farmed in the deep trough of the Yellow Sea, west and south of Jeju. Calculation with wind forcing only through a parameterized linear bottom friction produces almost same results from the calculation with $M_2$ tidal forcing and wind forcing using a quadratic bottom friction, supporting Hunter (1975)'s linearization of bottom friction which includes the effect of tidal current, can be applied to the simulation of wind-driven circulation in YSECS. The results show that steady wind forcing is not a dominant factor to the winter-time upwind flow in YSECS. Upwind flow experiment which considers the relaxation of pressure gradient (Huesh et al. 1986) shows that 1) a downwind flow is dominant over the whole YSECS when the northerly wind reaches a maximum speed; 2) a trend of upwind flow near the trough is found during relaxation when the wind abates; 3) a northward flow dominates over the YSECS after the wind stops. The results also show that the upwind flow in the trough of Yellow Sea is forced by a wind-induced longitudinal surface elevation gradient.

• Journal of the korean society of oceanography
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• v.34 no.4
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• pp.185-199
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• 1999

With a realistic geography and topography the Princeton Ocean Model is used to study the effects of topography, wind and time-varying Chanajiang (Yangtze) River discharge on the dispersion of the Chanaiiang River plume in the Yellow and East China Seas. The topographic feature of deepening offshore suppresses the offshore expansion of the discharged low salinity water while spreading along the coast is not hindered. Also the spreading of the Chanajiang River plume is very sensitive to wind conditions and the southerly wind is most responsible for the eastward expansion toward the Cheju Island. It is also shown that the influence of the Chanajiang River Diluted Water on the hydrography and circulation of the Yellow Sea including the South Sea of Korea is substantial even in the absence of tide, wind and current.

• Ocean and Polar Research
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• v.23 no.3
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• pp.223-242
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• 2001

This paper presents the depth-mean monthly variation in the circulation of the Yellow Sea and the East China Sea computed using a robust diagnostic model. The mixed three-dimensional finite-difference Galerkin function model developed by Lee et at. (2000, 2001) has been extended to take into account baroclinic effects and then used to calculate the depth-mean flow fields as part of the results. In addition to M2 tide and oceanic flows previously considered, the model has been driven by the monthly mean wind stresses from Na and Seo (1998), the density gradient calculated based on by GDEM data set released by US Navy. Model results are very encouraging in that many of observed features including Jeju Cyclonic Gyre and frontal eddies along the shelfside of the Kuroshio main stream and west of Kyushu, are satisfactorily reproduced and are expected to be of value in interpreting observations in various oceanograhic disciplines.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.6
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• pp.754-770
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• 1994

Suspended sediment distribution and water column processes in the upper Neuse River estuary, North Carolina, were monitored monthly from February 1988 through February 1989, in order to identify the turbidity maximum, to determine its temporal and spatial variation under changing conditions(freshwater runoff, wind, and tide). During most of the observation periods a weak turbidity maximum, associated with the estuarine circulation processes, developed at a flow convergence zone, near the upstream limit of salt intrusion. No turbidity maximum was found when the water column was vertically homogeneous with respect to salinity and when there was no consistent upstream bottom flow. Annual migration of the turbidity maximum, accompanied by migration of salt intrusion, was over 20 km of the upper estuary. Due to the coincidence of dominant wind direction(NE-SW) with the main orientation of the Pamlico-Neuse system, wind played the dominant role in dynamics of the turbidity maximum by influencing the degree of salinity stratification and the extent and strength of estuarine circulation. Tidal effects on the sediment dynamics were negligible.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.29 no.2
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• pp.77-100
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• 2024

Circulation, tides, currents, harmful algal blooms, water quality, and hypoxic conditions in Jinhae-Masan Bay have been extensively studied. However, these previous studies primarily focused on short-term variations, and there was limited detailed investigation into the physical mechanisms responsible for ocean circulation in the bays. Oceanic processes in the bays, such as pollutant dispersal, changes on a seasonal time scale. Therefore, this study aimed to understand how the circulation in Jinhae-Masan Bay varies seasonally and to examine the effects of tides, winds, and river discharges on regional ocean circulation. To achieve this, a three-dimensional ocean circulation model was used to simulate circulation patterns from 2016 to 2018, and sensitivity experiments were conducted. This study reveals that convective estuarine circulation develops in Jinhae and Masan Bays, characterized by the inflow of deep oceanic water from the Korea Strait through Gadeoksudo, while surface water flows outward. This deep water intrusion divides into northward and westward branches. In this study, the volume transport was calculated along the direction of bottom channels in each region. The meridional water exchange in the eastern region of Jinhae Bay is 2.3 times greater in winter and 1.4 times greater in summer compared to that of zonal exchange in the western region. In the western region of Jinhae Bay, the circulation pattern varies significantly by season due to changes in the balance of forces. During winter, surface currents flow southward and bottom currents flow northward, strengthening the north-south convective circulation due to the combined effects of northwesterly winds and the slope of the sea surface. In contrast, during summer, southwesterly winds cause surface seawater to flow eastward, and the elevated sea surface in the southeastern part enhances northward barotropic pressure gradient intensifying the eastward surface flow. The density gradient and southward baroclinic pressure gradient increase in the lower layer, causing a strong westward inflow of seawater from Gadeoksudo, enhancing the zonal convective circulation by 26% compared to winter. The convective circulation in the western Jinhae Bay is significantly influenced by both tidal current and wind during both winter and summer. In the eastern Jinhae Bay and Masan Bay, surface water flows outward to the open sea in all seasons, while bottom water flows inward, demonstrating a typical convective estuarine circulation. In winter, the contributions of wind and freshwater influx are significant, while in summer, the influence of mixing by tidal currents plays a major role in the north-south convective circulation. In the eastern Jinhae Bay, tidally driven residual circulation patterns, influenced by the local topography, are distinct. The study results are expected to enhance our understanding of pollutant dispersion, summer hypoxic events, and the abundance of red tide organisms in these bays.