동해의 순환 고찰을 위한 간단한 부력조정 모델의 적용

승영호 한국수산학회 1988 한국수산과학회지 Vol.21 No.6

Application of the simple buoyancy adjustment model, similar to Davey's(1983), indicates that buoyancies imposed locally or from outside of the basin are the major factor of the Japan Sea circulation. Within the context of the model considered, the relatively strong EW gradient of temperature, and corresponding western boundary current, in the SW region is due to the beta-effect. Kelvin waves make the western side colder and the eastern side warmer. Buoyancy input (presumably by fresh water discharge) in the NW region, so far neglected, plays an important role in strengthening the NKCC(North Korea Cold Current) and suppressing the EKWC(East Korea Warm Current) thereby breaking the conventional branching system of the Tsushima Warm Current.

Evidences of Intermittent Wind-Induced Flow in the Yellow Sea obtained from AVHRR SST Data

승영호,Jong-Hyuk Yoon,Eun-Pyo Lim 한국해양과학기술원 2012 Ocean and Polar Research Vol.34 No.4

Ten-year AVHRR sea surface temperature data obtained in the Yellow Sea are put into EOF analyses. Temperature variation is predominated by the first mode which is associated with the seasonal fluctuation of temperature with annual range decreasing with the bottom depth. Since such a strong annual signal may mask the upwind or downwind flows occurring intermittently during the winter, only the data obtained during this season are put into EOF analyses. Every winter shows similar results. The first mode, explaining more than 90% of total variance, appears to be a part of the seasonal variation of temperature mentioned above. In the second mode, the time coefficient is well correlated with northerly winds to which the responses of the trough and shallow coastal areas are opposite to each other. A simple theoretical consideration suggests the following physical explanation: The northerly wind stress anomaly creates an upwind (downwind) flow over the trough (coastal) areas, which then induces a temperature increase (decrease) by advection of heat, and vice versa for the southerly wind stress anomaly. Hence, this paper provides further evidence of the intermittent upwind or downwind flows occurring in the Yellow Sea every winter.

Seasonal Variation of Volume Transport through the Straits of theEast/Japan Sea Viewed from the Island Rule

승영호,Soo-Yeon Han,Eun-Pyo Lim 한국해양과학기술원 2012 Ocean and Polar Research Vol.34 No.4

Among others, a question that has long been unanswered is why the seasonal variation of volume transport is larger in the Soya and Korea/Tsushima Straits than in the Tsugaru Strait. An attempt is made to answer this question in terms of the island rule with friction being taken into account. The problem is idealized as a simple model. The model results indicate that volume transport through a channel is determined not only by the circulation created around the adjacent island but also by those created around the neighboring islands farther away. The latter is due to the presence of bottom friction in the channels. The volume transports through the Korea/Tsushima, Tsugaru and Soya Straits estimated from the model using observed wind data show the general pattern of observed seasonality, although they contain large errors associated with the uncertain frictional parameter employed in the model. The model indicates that the observed seasonality arises essentially from the fact that wind stress curl changes its sign, from negative in the summer to positive in winter, following a large fluctuation of zero-stress curl latitude east of Hokkaido.

Effect of Shantung Peninsula on the Development of Mean Upwind Flow in the Yellow Sea

승영호,Seung, Young-Ho The Korean Society of Oceanography 1995 韓國海洋學會誌 Vol.30 No.6

Effect of Shantung Peninsula on the development of mean upwind flow in the Yellow Sea in winter is analysed using a simple model. The results indicate that the disturbances generated by the Shantung Peninsula have a scale much larger than the basin scale whereas disturbances, if any, generated similarly on the other side of the trough has much smaller scale. The effect of Shantung Peninsula thus dominates over the whole basin and deflects westward the otherwise northward upwind flow.

Some High-Frequency Variability of Currents Obtained by “GeoDrifters” in the Tsushima Current Region

승영호,박종진,권영연,김성준,김홍선,박용철 한국해양과학기술원 2017 Ocean and Polar Research Vol.39 No.3

The “GeoDrifter” is a newly-developed surface drifter with high temporal resolution. It is the first time that high-frequency drifters have been deployed in the East/Japan Sea. The purpose of this study is to introduce the phenomena experienced by these drifters flowing along with the Tsushima Current across the East/Japan Sea, focusing on high-frequency variability, and to discuss them in comparison with previous observations. The observed basin-scale circulation of the Tsushima Current generally coincides well with the known schematic circulation. The GeoDrifter trajectories also show inertial oscillations almost everywhere in the oceanic regions of the East/Japan Sea, strong semi-diurnal tidal currents in the western part of Korea Strait, diurnal currents much stronger than semi-diurnal currents in the upstream region of the Nearshore Branch off the Japanese coast, and many warm eddies in the Yamato Basin, all comparable to the observational results reported in the previous studies. An interesting point is that the semi-diurnal tidal currents undergo a great spatial variation in the western part of the Korea Strait. The observed features that cannot be explained are, among others, strong counter-clockwise motions with oscillating period about 51 hours appearing in the upstream region of the Nearshore Branch off the Japanese coast and the different tidal behaviors between upstream and downstream regions of the latter.

Taiwan Warm Current and Onshore Intrusion of Kuroshio

승영호 대한조선학회 2011 대한조선학회 학술대회자료집 Vol.2011 No.6

An Advection-Diffusion Model for the Distribution of Surface Cold Water near UIgi(Ulsan), SE Korea

승영호,Seung, Young-Ho The Korean Society of Oceanography 1988 韓國海洋學會誌 Vol.23 No.1

A simple model is presented which may explain the distributions of cold surface water near Ulsan. The model considers the problem as an advection-diffusion process with cold source confined within narrow coastal areas. The natural warming due to vertical process (interaction either with the atmosphere above or with the subsurface water below) also plays an important role. A simple numerical computation reproduces the observations quite well. The localization of cold surface water occurs at the point where the local warm current separates from the coast.

On the Possible Role of Local Thermal Forcing on the Japan Sea Circulation

승영호,김구,Seung, Young-Ho,Kim, Kuh The Korean Society of Oceanography 1989 韓國海洋學會誌 Vol.24 No.1

It has been believed that the circulation in the Japan Sea involves separation of current from the Korean coast and formation of a cold cyclonic gyre in the north. To explain this, a simple quasi-geostrophic linear model is considered. The model is basically of an inflow-outflow system. The local forcings, wind and air-sea heat exchange together with damping (both mechanical and thermal), are imposed upon. The results show that only the buoyancy damping due to perturbations from local thermal adjustment can cause the separation and the gyre. Various types of circulation patterns are possible depending on the intensity of the thermal forcing.

8월의 한국동안에서의 수온분포에 관한 역학적 고찰

승영호,Seung, Young Ho 한국해양학회 1974 韓國海洋學會誌 Vol.9 No.1

The water temperature distribution and the water movement closely related with it, in the east side of Korea, was condidered. Special emphasis was paid on the low temperature phenomenon near Ulgi. It was known from the temperature distribution in the east side of Korea that the Tsushima current continues to flow northward at the surface near Sokcho. Also the influence of the cold water extends from the North to the South with increasing depth. The formation of the cold core near Ulgi was explained as due mainly to the existence of the boundary layer near the surface, and partly to the effect of the wind. This inclination of the boundary layer has the value of about 3.0m/Km, and the lower cold current velocity computed using this value lies in the range of those observed by Nishida(1926, 1927). The upwelling velocity was computed approximately as 1.4 10$\^$-3/ cm/sec, and the maximum distance to which the boundarylayer can rise or fall from it's equilibrium position was considered as below 10m.

한반도 주변의 수괴와 해수순환

승영호 한국해양학회 1992 韓國海洋學會誌 Vol.27 No.4

Water masses and circulations around Korean peninsula are briefly described based on recent studies. The results of theses studies are discussed from the physical point of view. Oceanic conditions in this region are largely due to the roles played by the Tsushima Warm Current, an onshore extension of the Kuroshio, and local conditions such as wind, surface heat flux and fresh water input etc. To the south and west of Korea, the northern/western border of the Tsushima Warm Current Water is roughly the line joining Taiwan and Cheju island. In summer, it is affected by large amount of fresh water discharged from the Changjiang and in winter, an intrusion of this water into the Yellow Sea is induced by the prevailing northwesterly monsoon wind. To the east of Korea, the Tsushima Warm Current Water presents roughly south of the line joining the wast coast of Korea near 37-38$^{\circ}$N and Tsugaru-Soya Straits in the northern Japan. But this situation, together with those in deeper layers, may greatly be changed by winter atmospheric conditions (wind and surface heat flux). The seas around Korea are not yet physically well understood and many problems wait physical explanations. Some problems, along with personal views of them, are mentioned.