• Journal of the korean society of oceanography
• /
• v.39 no.3
• /
• pp.155-162
• /
• 2004

The variation of volume transport during the period from 1965 to 2000 through the western channel of the Korea Strait was estimated by obtaining an relation function between the ADCP volume transport and the geostrophic volume transport estimated by the sea level difference between Pusan and Izuhara. The estimated climatological mean volume transport during past 36 years has seasonal variation with a minimum of 1.15 Sv in February and a maximum of 1.88 Sv in October. The mean volume transport for 36 years is 1.51 Sv. The annual mean volume transport has an interannual variation with a minimum of 1.26 Sv in 1968 and maximum of 1.90 Sv in 1973, with three dominant periods of variations of 14.96 years, 4.96 years and 2.99 years.

• Ocean and Polar Research
• /
• v.31 no.4
• /
• pp.283-296
• /
• 2009

Oceanographic survey data were analyzed to understand the characteristics of a warm eddy observed in the Ulleung Basin in July 2005. The temperature distribution at 200 db and vertical sections provided evidence of the warm eddy in the Ulleung Basin (UWE05). Based on the 5$^{\circ}C$ isothermal line on 200 db temperature, the major axis was 160 km from southwest to northeast, and the minor axis was 80 km from southeast to northwest. The homogeneous layer in the thermocline of UWE05 had mean values of 10.40$^{\circ}C$ potential temperature, 34.35 psu salinity, and 26.37 kg/m$^3$ potential density (${\sigma}_{\theta}$) and provided evidence that UWE05 also existed during the winter of 2004-2005. A warm streamer initially flowed along the circumference of UWE05 and mixed with the upper central water. Two northward current cores were found on the western side of the measured current section at the central latitude of UWE05. One was the East Korean Warm Current (EKWC) and the other was the main stream of the western part of UWE05. Geostrophic transport of the upper layer (from the surface to the isopycnal surface of 26.9 ${\sigma}_{\theta}$) was approximately 2.5 Sv in the eastern side of UWE05. However, the measured transport was twice as large as the geostrophic transport. Mass conservation of geostrophic transport was well satisfied in the upper layer. The direct current measurements and geostrophic transport analysis showed that the EKWC meandered around UWE05.

• Ocean and Polar Research
• /
• v.21 no.2
• /
• pp.99-108
• /
• 1999

With sectional data obtained in September of 1987, 1988 and 1989 by quadrireciprocal ADCP measurement and CTD cast, the current structure, volume transport and vorticity in the Western Channel of the Korea Strait were studied. The characteristics of Tsushima Current water persisted throughout the summer especially in the homogeneous water of temperature $14-16^{\circ}C$ located at the depth of 50-100m below seasonal termocline. Thickness and velocity of the homogeneous layer are about 10-170m and 20-60cm/s. and the relative vorticity for this layer is shown to be nearly constant and it is smaller than the planetary vorticity. Potential vorticity of $2.70-7.10{\times}10^{-6}m^{-1}s^{-1}$ is found to be dependent mainly on planetary rather than on the relative vorticities. The Tsushima Current water represented by the homogeneous layer R14-16^{\circ}C$ may keep the potential vorticity at the area of strong current in the Strait. The ADCP current structure is similar to geostrophic current and the core of the current with the speed of 30-50cm/s is situated in the middle layer over the deep trough. With large tidal fluctuation the volume transport has mean value of 1.17sv which was about 40% larger than that of geostrophic calculation.

• Korean Journal of Remote Sensing
• /
• v.9 no.1
• /
• pp.79-93
• /
• 1993

The relative geostrophic velocity is estimated by using the MCSST(Multi-Channel Sea Surface Temperature) from a NOAA/AVHRR image and applied to the Korea Strait. Remote sensing technique can play a useful role to research for oceanic phenomena because of its synoptic, simultaneous and repetitive viewing. The high resolution data of AVHRR can determine the geostrophic flow more precisely than the hydrographic data on shipboard. As a result of research, the relative geostrophic velocity in the weatern channel of the Korea Strait is the strongest in the trough area and its maximum speed is about 23.8cm/sec in April, 1992. But this results include the error due to neglecting the effect of salinity in estimation the geopotential anomaly. The geostrophic volume transport through the western channel of the Korea Strait is the largest between trough area and the Tsushima Island.

• 한국해양학회지
• /
• v.20 no.1
• /
• pp.50-55
• /
• 1985

With the serial observation data of the Fisheries Research and Development Agency in Korea and Japan Meteorological Agency from 1969 to 1974, the geostrophic current and volume transport were calculated in the Korea Strait and in the middle of the East Sea (Japan Sea), in order to compare the total volume transport in summer and winter seasons. The results are as follows. The annual mean of the net volume transport of the Korea Strait is 0.19${\times}$10$\^$6/m$\^$3/sec in winter season and 1.33${\times}$10$\^$6/m$\^$3/sec in summer season. The transport through the western and eastern channel of the Korea Srait is almost same in winter season, but the transport of the western channel is much larger than that of the eastern channel in summer season. The annual mean of the net volume transport of the middle section of the East Sea (Japan Sea) is 2.61${\times}$10$\^$6/m$\^$3/sec in winter season and 2.41${\times}$10$\^$6/m$\^$3/sec in summer season. Therefore the transorts are almost same in both seasons. Comparing the transports of the two sections, the transport through the middle section of the East Sea is 13.7 times as large as that of the Korea Strait in winter season and 1.8 times in summer season.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.30 no.5
• /
• pp.759-770
• /
• 1997

The general flow patterns in the Cheju Strait have been investicated by analyzing the current observations measured in $1986\~1989$ by current meter mooring in 3 north-south sections in the Cheju Strait and at 4 observation points around Cheju Harbour, and measured in $1981\~1987$ by drogue tracking. 1. In the Cheju Strait, there are eastward or northeastward residual currents, which implies that sea waters flow into through the whole western section and flow out through the whole eastern section in the Cheju Strait. The velocity of residual currents are $5.2\~30\;cm/sec$ in 10 m layer and $1.3\~24cm/sec$ in mid-bottom layer. Generally, the flow is strong along the deepest through and the northern part, and weak in the shallow areas near Chuja Islands and Bogil Island. 2. In the western entrance of the Cheju Strait, the observed mean residual velocity is 6.93 cm/sec and the volume transport is 0.384 Sv. There are a big discrepancy between the observed residual currents and the geostrophic currents. 3. Near the frontal areas northwest to Chuja Islands, warm and saline offshore waters, flow northward about 5 miles into the southern coastal areas of the Korean Peninsula in flood, and flow back rather eastward or southeastward than southward in ebb. So, warm and saline waters flow along coastal areas, being mixed with coastal waters. As a result, the northwestern area of Chuja Islands plays a role of the entrance of influx of warm and saline offshore water to the southwestern coastal areas of the Korean Peninsula. It should be stressed that this flow pattern is not due to the residual flows, but to the temporal (tidal) flows.

• Ocean Science Journal
• /
• v.40 no.1
• /
• pp.25-44
• /
• 2005

Long-term, continuous, and real-time ocean monitoring has been undertaken in order to evaluate various oceanographic phenomena and processes in the East/Japan Sea. Recent technical advances combined with our concerted efforts have allowed us to establish a real-time monitoring system and to accumulate considerable knowledge on what has been taking place in water properties, current systems, and circulation in the East Sea. We have obtained information on volume transport across the Korea Strait through cable voltage measurements and continuous temperature and salinity profile data from ARGO floats placed throughout entire East Sea since 1997. These ARGO float data have been utilized to estimate deep current, inertial kinetic energy, and changes in water mass, especially in the northern East Sea. We have also developed the East Sea Real-time Ocean Buoy (ESROB) in coastal regions and made continual improvements till it has evolved into the most up-to-date and effective monitoring system as a result of remarkable technical progress in data communication systems. Atmospheric and oceanic measurements by ESROB have contributed to the recognition of coastal wind variability, current fluctuations, and internal waves near and off the eastern coast of Korea. Long-tenn current meter moorings have been in operation since 1996 between Ulleungdo and Dokdo to monitor the interbasin deep water exchanges between the Japanese and Ulleung Basins. In addition, remotely sensed satellite data could facilitate the investigation of atmospheric and oceanic surface conditions such as sea surface temperature (SST), sea surface height, near-surface winds, oceanic color, surface roughness, and so on. These satellite data revealed surface frontal structures with a fairly good spatial resolution, seasonal cycle of SST, atmospheric wind forcing, geostrophic current anomalies, and biogeochemical processes associated with physical forcing and processes. Since the East Sea has been recognized as a natural laboratory for global oceanic changes and a clue to abrupt climate change, we aim at constructing a 4-D continuous real-time monitoring system, over a decade at least, using the most advanced techniques to understand a variety of oceanic processes in the East Sea.