Characteristics of Physical Properties in the Ulleung Basin

김구,김경렬,정종률,유홍선,박상갑,Kim, Kuh,Kim, Kyung-Ryul,Chung, Jong-Yul,Yoo, Hong-Sun,Park, Sang-Gap The Korean Society of Oceanography 1991 韓國海洋學會誌 Vol.26 No.1

A layer of salinity-minimum which characterizes the East Sea intermediate Water (ESIW) is found at an approximate depth of 200 m in three CTD section taken in the Ulleung Basin on May 17-21, 1988. Properties at this layer vary in ranges of $1.1^{\circ}C<T<2.7^{\circ}C{\;}and{\;}34.02{\textperthousand}<S<34.11{\textperthousand}$ except at stations near the east coast of Korea where temperature is as high as $4.39^{\circ}C$ and salinity is as low as $33.992{\textperthousand}$. To be distinguished from the ESIW the East Sea Proper Water (ESPW) may be characterized by temperature less than $1^{\circ}C$, Salinity at the saliently-minimum layer and 500db increases southward in general, implying that the cold waters, both ESIW and ESPW, formed in the northern basin of the East Sea are spreading southward below the permanent thermocline in the basin. Hydrography in the Ulleung Basin is very similar to that in the Alboran Sea, suggesting a possibility of an anticyclonic circulation in the Ulleung Basin which is controlled strongly by the shoaling bottom.

제주도 서안에 존재하는 균질해수

김구,이상호,Kim, Kuh,Lee, Sang Ho 한국해양학회 1982 韓國海洋學會誌 Vol.17 No.2

Vertically homogeneous water was found around the convex coast of Jeju Island on its west side from hydrographic surveys conducted in June and Ictober 1980, and June 1981. This is the first time that this hydrographic structure is observed. Historical data do not show this water, since they wewe taken far from the island. The presence of this homogeneous water is explained in terms of tidal mexing for the lower half of the water column and relling for the upper half of the columa which conserve vorticity as currints flow clockwise around the island. Direct measurement in future is required to prove the upwelling mechanism.

하계 제주도 주변의 해역 및 해수순환

김구,노홍길,이상호,Kim, Kuh,Rho, Hong-Kil,Lee, Sang-Ho 한국해양학회 1991 韓國海洋學會誌 Vol.26 No.3

1980년 6월과 1981년 8월 제주해협과 황해의 동남 해역에서 8-16해리 간격으로 수 온-염분의 정밀 관측을 실시한 결과, 대양성의 고온 고염수가 제주도 서쪽연안 20 km 이내에 존재함을 발견하였다. 동시에 제주도 주변 해역의 표층에 나타나는 저염분 골 이 양자강퇴 해역의 저염분수에서 기원함이 확인되었다. 이 골에 의해 고온 고염수는 황해 표층수와 분리되며, 저층에서는 황해의 저층냉수와 전선을 이루고 있다. 황해 냉 수는 양자강퇴의 70 m 수심을 따라 동지나해를 향하여 남하하며, 또한 부분적으로 제주 해협의 북쪽 단면에도 나타나 남해로 유입 가능성이 크다. 이러한 복잡한 수계구조와 공간적 분포는 황해난류가 한국 서해안을 향하여 북상한다는 기존 학설(Uda, 1934)과 는 일치하지 않으며, 지속적인 조밀한 정선관측을 제주도 주변 해역에서 순서하여 해 류 구조의 시·공간적 변동상을 파악하여야 한다.

제주도 주변 M 2조의 진폭변화

김구,이상호,Kim, Kuh,Lee, Sang-Ho 한국해양학회 1986 韓國海洋學會誌 Vol.21 No.3

The amplitudes of the M2 tide recorded at Seoguipo and Jeju are 77.9cm and 70.1cm respectively, which differ by 7.8cm over a distance of 30km across the Jeju-Do. The difference is an example of the geographical variation of the tidal amplitude around the Jeju-Do, the larger amplitude being along its southern coast compared with that along its northern coast. This variation can be explained in terms of effects of an island on the wave propagation as modelled by Proudman(1914). A numerical experiment of the M2 tide around the Jeju-Do reproduces the basic pattern of the observed variation and results are consistent with the theory. Due to the rotation of the earth larger and smaller amplitudes result along the left-hand and right-hand coasts of an island for an observer facing the direction of the wave propagation in the northern hemisphere.

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.

제주와 목포, 제주와 완도간의 표면수온 변화

노홍길,김구,Rho, Hong Kil,Kim, Kuh 한국해양학회 1983 韓國海洋學會誌 Vol.18 No.1

A series of sheps-of-opportunity sea sryface temperature (SST) measurement beween Jeju and Wando during a period from December 1979 through June 1981 produced following results. 1. A sihnificantly warm water appeared south of Chuja Island and Cheongsan Island during Island. It is suggested that this water represents a current entering the Jeju Strait from the west. Direction of this currint in other seasons is not certain. 2. Coastal waters were found north of the Cheongsan Island and Bogil Islhnd throughout the measurement period. In February these waters sometimes reached as far as Chuja Island to south. 3. Frequently thermal fronts were observed near the Chuja Island and the Cheongsan Island. 4. In summer cold waters appeared north of the Chuja Island and Changsu Island. Intrusion of cold bottom water from offshore and its subsequent vertical mixing due to strong tidal current are probably reponsible for this appearance. 5. Cold waters also appeared locally around islands and in ghe Jeju Harbor in spring and summer. 6. North-south SST difference reached 8-9$^{\circ}C$ in winter which is the annual maximum. 7. Annual range of SST varies from 12-14$^{\circ}C$ in the central part of the Jeju Strait to 16-20$^{\circ}C$ in coastal waters to north. The highest SST appeared everywhere in September but the lowest one did not appesr in the same month of year.

한국 동해안에 출현하는 냉수괴의 특성과 기원

김철호,김구,Kim, Cheol Ho,Kim, Kuh 한국해양학회 1983 韓國海洋學會誌 Vol.18 No.1

To serch the origin of the cold water mass along the east coast of Korea its characteristics are inrestigated based upon Cooperative Study of Kuroahio and Fisheries Research and Development Agency data. In the southwestern part of the Japan Sea the North Korean Cold Water sinks at the front and flows southwards on top of the Japan Sea Proper Water. it is found that the sunken North Korean Cold Water il high in the content of dissolved oxygen and less saline compared with the Japan Sea Proper Water. It is highly likely that the cold water mass off the Jugbyeon-Chuksan coast in summer il the North Koreah Cold Water and not upwelled Japan Sea Proper Water. It os shown that the Notth Korean cold Water Flows strongly in summer and its scuthern limit is generally off Chuksan-Janggigab and occasionally off Gampo as observed in 1973.

Variations of the Diurnal Tides around Jeju-Do

이상호,김구,Lee, Sang Ho,Kim, Kuh The Korean Society of Oceanography 1988 韓國海洋學會誌 Vol.23 No.2

Analyzing short-term records of sea level data, we show that the amplitudes of diurnal tides along the southern coast of Jeju-Do are significantly larger than those along its northern coast. The amplitude-phase diagrams of $K_1$ and $O_1$ look very similar to that of $M_2$ shown by Kim and Lee (1986), indicating characteristics of the scattering of long waves by Jeju-Do.

가을철 대한해협 표면혼합층의 단기변화

장찬주,김구,심태보,Jang, Chan-Joo,Kim, Kuh,Shim, Tae-Bo 한국해양학회 1995 韓國海洋學會誌 Vol.30 No.5

To investigate a short-term (from 2 hours to 24 hours) variability of a mixed layer, oceanographical data (water temperature, salinity, current) and meteorological data (wind, air temperature, solar radiation) were collected at a site in the Korea Strait at the interval of one hour for 48 hours from October 12 to 14, 1993. The average rates of temporal variations of the mixed layer depth (MLD) and temperature of the mixed layer (MLT), which are very weakly correlated with the wind stress and buoyancy flux at the sea surface, are about 5.2 m/hour and 0.2$^{\circ}C$/hour, respectively. The mixed layer is relatively shallow when both MLT and MLS (salinity of the mixed layer) are low, while MLD is relatively deep when they are high. MLT shows a sudden decrease or increase. Analysis of satellite infrared images and XBT data shows that sudden increase of MLT is caused by advection of warm water. These results suggest that the short-term variation of the mixed layer in the Korea Strait in autumn, in which surface current is relatively strong and different water masses exist, is mainly determined by advection rather than air0sea interaction such as wind stress or buoyancy flux.

1983년 춘계 제주해협의 해황과 해류

장경일,김구,이석우,심태보,Chang, Kyung-Il,Kim, Kuh,Lee, Suk-Woo,Shim, Tae-Bo 한국해양학회 1995 韓國海洋學會誌 Vol.30 No.3

Two hydrographic surveys along with direct current measurements using drogues and moored current meters were conducted in Cheju Strait during April and May, 1983. The data clearly demonstrate that a branch of the Kuroshio characterized by high temperature and high salinity enters the Cheju Strait after turning around the western coast of Cheju-Do. The width of the current turning west of Cheju-Do is about 60 km and reduces to 20∼30 km in the strait, resulting in a high speed(>10 cm/s) at the western entrance and in the middle of the strait, compared with a low speed (>5 cm/s) west of Cheju-Do. The Tsushima Current water also originating from the Kuroshio shows its influence in the eastern part of the Cheju Strait. Thermohaline fronts formed between the warm current waters and the coastal waters suggest the southward extension of the Yellow Sea Coastal Water west of the Cheju Strait. A warming of the warm current waters occurs in May, while a cooling takes place in other areas. The major freshening and cooling of water take place in the middle of the Cheju Strait in May due to the intrusion of cold and low salinity water from the west of the Cheju Strait.