• Ocean and Polar Research
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• v.25 no.4
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• pp.503-518
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• 2003

This study examines the relationship among temperature, wind, and sea level pressure to understand recent warming in the vicinity of the Antarctic Peninsula. To do this, the surface air temperature, NCEP/NCAR reanalysis wind data and sea level pressure data for the period of 40 years are analyzed. The 40-year surface air temperature data in the Antarctic Peninsula reveals relatively the larger warming trends for autumn and winter than other seasons. The variability of the surface air temperature in this region is compared with that of the regional atmospheric circulation. The surface air temperature is positively correlated with frequency of northwesterlies and negatively correlated with frequency of southeasterlies. This relation is more evident in the northern tip of the Antarctic Peninsula for autumn and winter. The trend analysis of wind frequency in the study area shows increasing and decreasing trends in the frequency of northwesterlies and southeasterlies, respectively, in the northwestern part of the Weddell Sea for autumn and winter. And also it is found that these winds are closely related with decreasing of sea level pressure in the southeastern region of the Antarctic Peninsula. Furthermore from the seasonal variation of sea level pressure in this area, it may be presumed that decreasing of sea level pressure in the southeastern region of the Antarctic Peninsula is related with warming in the vicinity of the Antarctic Peninsula for autumn and winter. Therefore it can be explained that recent warming in the vicinity of the Antarctic Peninsula is caused by positive feedback mechanism, that is, the process that warming in the vicinity of the Antarctic Peninsula can lead to the decrease of sea level pressure in the southeastern region of the Antarctic Peninsula and these pressure decrease in turn lead to the variation of wind direction in northwestern part of Weddell Sea, again the variation of wind direction enhances the warming in the Antarctic Peninsula.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.24 no.6
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• pp.390-399
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• 2012

This research observed the cross section current of 7 survey lines in Seokmo Channel of Gyeonggi bay with a lot of freshwater inflow and S-shaped for 13 hours during flood season and neap tide. We indicated the distribution of the current velocity by comprehending the speed and direction of the current velocity of each line during maximum flood, ebb tide and observed the distribution of salinity. Moreover, in order to understand what lateral momentum causes the lateral flow in each survey line, we practiced the momentum analysis through the observation data. As a result, the lateral baroclinic pressure gradient force and vertical friction of the Seokmo channel during neap tide were the strongest, and this is why the flow by the distribution of salinity and stratification most often occurs. In north of the Seokmo channel, where have wide intertidal and a lot of freshwater inflow, the secondary circulation is caused by balance of lateral baroclinic pressure gradient force and other forces, and the vertical friction was strong in the lines with small depth. On the other hand, in the southern part of the Seokmo channel where the water is deep and the waterway is curved, the advective acceleration and centrifugal force become stronger by the geographical causes during ebb and the influence of fresh water. Therefore, the lateral flow in the Seokmo channel was caused by the distribution of the momentum that differs by location, depth, curve, etc.

• Journal of Navigation and Port Research
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• v.40 no.1
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• pp.1-6
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• 2016

This study was conducted on a circulation system which can recycle waste water from EGCS(Exhaust Gas Cleaning System) using a wet scrubber that is used to treat air pollutants from ships. Though we developed a water treatment system that could remove effectively particulate matters and dispersed oil included in cleaning water for Ship Exhaust Gas Recycle System(DePM & DeSOx), we found that it is difficult to treat minutely dispersed oil only by means of centrifugal-typed purifier. Therefore, to this system, we applied a coalescer that coalesces emulsified minute oil particles in the 2nd phase of dispersion state after being filtered through the centrifugal-typed purifier. After we treated cleaning water drained out of Ship Exhaust Gas Recycle System(DePM & DeSOx) by using both purifier and coalescer, we found that particulate matters and dispersed oil were removed more than 55% and 99%, respectively, in comparison with those contained in cleaning water influent. Putting the results together, we conclude that the treated cleaning water can be recycled as normal cleaning water if this cleaning water treatment system is employed by the wet cleaning tower system for the reduction of air pollutants from ships.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.3
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• pp.164-174
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• 2008

In this study we try to identify the three-dimensional mixing characteristics of Seomjin River discharges in Seomjin River Estuary and Gwangyang Bay using a seasonal field observation (CTD) during spring tide and a three-dimensional numerical model with EFDC (Environmental Fluid Dynamics Code). The tidal elevation conditions of the four main tidal harmonic constituents on the open boundary and river discharges and thermal effluents at the specific boundary are considered. The calculated harmonic constants of tide and tidal current agreed well with those of observations at two stations for tide and two stations for tidal current. The model successfully reproduced well known the estuarine circulation in Seomjin River Estuary where tide and river discharges are dominant forcings. In the winter mean discharges case, tidal currents move Seomjin River discharges in Seomjin River mouth and in the summer mean discharges case, river flows move Seomjin River discharges near ae Seomjin River Estuary. A three-dimensional mixing characteristics of Seomjin River Estuary show well a three-dimensional estuarine circulation and thermal effluents effect to the seasonal variation of river discharges.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.1
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• pp.43-52
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• 2006

Numerical model tests are done in order to evaluate impact zone of low salinity water on outer region of the developing Saemankeum reservoir. Also saline mixing processes are investigated f3r the inner reservoir with consideration of Mankyoung and Donjin riverine flood discharges when sea water is passing freely through gate. In these analyses 2-d ADCIRC, 3-d TIDED3D and CE-QUAL-ICM models are used. Through models tests, it is found that inner reservoir mixing process caused by inflow of outer sea water occurs gradually. It takes at least one month for complete mixing on Mankyoung part and 6 month on Dongjin part of the reservoir. When Sinsi or Garyeok gates are opened to control inner reservoir level, discharging velocities decrease exponentially from the gates, but show very strong currents of 0.5m/sec to the 10Km region apart. These results imply that hydrodynamic circulation and ecosystem of frontal region of the Saemankeum dike might be affected in amount by gate operations, since low saline inner waters are discharged periodically at ebb tide according to tidal level.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.20 no.4
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• pp.199-205
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• 2015

Nitrogen and phosphorus are the limiting elements for growth of phytoplankton, which is a major primary producer of marine ecosystem. Incidentally the stoichiometry of N/P of ocean waters, measured by the (nitrate + nitrite)/phosphate ratio converges to a constant of 16. This characteristic ratio has been used widely for the understanding the ecosystem dynamics and biogeochemical cycles in the ocean. In the East Sea, several key papers were issued in recent years regarding the climate change and its impact on ecosystem dynamic and biogeochemical cycles using N/P ratio because the East Sea is a "miniature ocean" having her own meridional overturning circulation with the appropriate responding time and excellent accessibility. However, cited N/P values are different by authors that we tried to propose a single representative value by reanalyzing the historical nutrient data. We present N/P of the East Sea as $12.7{\pm}0.1$ for the year 2000. The ratio reveals a remarkable consistency for waters exceeding 300m depth (below the seasonal thermocline). We recommend to use this value in the future studies and hope to minimize confusion for understanding ecosystem response and biogeochemical cycles in relation to future climate change until new N/P value is established from future studies.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.4
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• pp.207-218
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• 2013

This study is based on a series of numerical modeling experiments to understand the circulation and its change in the Chunsu Bay (CSB), Yellow Sea of Korea. A skill analysis was performed for the tidal height and tidal current of the observation data using the amplitude and phase of the 4 major tidal constituents respectively for verification of modeling experimental results. As a result, most of the skill score was seen to be over 90%, so numerical model experiment results can be said to be in good agreement with the observed tidal height and tidal current. Tidal wave proceeded from the entrance of the CSB towards inside, and the tidal range gradually increased to the north. It took about 10 to 30 minutes for the tidal wave to reach to northern end. The tidal wave showed a characteristic to rotate counter-clockwise in the southern part. The tidal current flowed to the north-south direction along the bottom topography; the angle of the major axis appeared alongside the isobath. It showed the characteristics of reversing tidal current with the minor axis less than 10% of the major axis. The strength of the tidal residual current that is influenced by geographical factors including bathymetry and coastline showed the range of 1~30 cm/sec, greater in the south channel and smaller in northern Bay. Two pairs of cyclonic/anti-cyclonic eddies around Jukdo and 3~4 pairs of strong eddies at the southern part of CSB in hundreds of m to a few km size by relative vorticity derived from the tidal residual current.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• v.23 no.1
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• pp.18-33
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• 1995

Under the synoptic scale strong westerly winds flowing over the large steep mountains in the eastern coastal region, the strong downslope wind storms such as internal gravity waves should be generated in the lee-side of mountain. Int he daytime as sea breeze circulation induced by meso-scale thermal forcing from sea toward inland confines to the offshore side of coastal sites due to the eastward internal gravity waves. Thus, surface winds near the coastal seas were relatively weaker than those in the open sea or the inland sites. Evidently, two different kinds of atmospheric circulations such as an internal gravity wave circulation with westerly wind and a sea breeze circulation with both easterly wind near the sea surface and westerly in the upper level were apparently produced. Under this situation the atmospheric pollutants at Kangnung city should be trapped by two different circulations in the opposite directions and resulted in the high concentrations of Total Suspended Particles (TSP) and ozone (O3). At night a meso-scale land breeze from land toward the more intensification of westerly winds in the coastal regions. The concentrations of TSP controled by the strong surface winds blowing from the mountain side toward the coastal sea were relatively higher at night than those in the daytime case and the concentrations of O3 due to the downward transport of ozone from the upper atmosphere toward the surface were also much higher at night than during the day. Consequently, the atmospheric pollutant concentrations in the mountainous coastal region under the downslope wind storms were higher than those after and before the occurrences of wind storms.

• Journal of the Korean earth science society
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• v.23 no.4
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• pp.369-379
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• 2002

The characteristics of the East Asian summer monsoon circulation associated with the cool and wet summer of 1993 and the warm and dry summer of 1994 are investigated by analyzing the atmospheric circulations features in the upper and lower troposphere and by examining the global SST and associated tropical convective precipitation fields. The negative geopotential height anomalies at 500 hPa and 200 hPa in 1993 over East Asia, the central North Pacific, and the western United States were replaced by positive ones in 1994. In addition, the 200 hPa zonal wind anomaly averaged over the East Asian summer monsoon region is negatively correlated with the Korean summer temperature anomaly. The subtropical jet stream in 1993 was displaced into the central part of Korea well south of its normal position. The western Pacific subtropical high was shifted southward, and the East Asian summer rainfall and temperature was above-normal and below-normal, respectively due to the southwestward extension of a cold and dry polar airmass from the Sea of Okhotsk to the Est Sea. In contrast, the subtropical jet stream in 1994 was displaced well north of its normal position. The abrupt northward shift of the western Pacific subtropical high was accompanied with the rapid northward movement of the rain band of the East Asian summer monsoon rainfall. The anomaly patterns of the East Asia summer rainfall and temperature were opposite to those of 1993. Large sea surface temperature anomalies of opposite signs existed in the tropical Pacific with a mature El $Ni{\~{n}o$ in 1993 and a weak La $Ni{\~{n}a$ condition in 1994. The role of the anomalous convective precipitation in the western Pacific and the Indian Ocean related with the variations in the low-level cross-equatorial flow along the northwestern periphery of the Australian high and the Mascarene high is probably to influence a large-scale atmospheric circulation over the East Asia during both the years.

• Journal of Navigation and Port Research
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• v.27 no.2
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• pp.233-238
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• 2003

Due to the impermeability of outer wall facilities such as Breakwaters which dissipates the wave energy and keeps harbor tranquility, the enclosed area of harbor becomes partially blocked and the water exchange can be reduced. Recent trends of port development protect water quality and emphasize Water-Front, so the method which enhances the circulation of harbor waters and the dilution of the water pollutants are studied. The best improvement of water quality is a remove of pollutant source on land, but an enclosed port must be enhanced the tidal exchange. For this end, the best improvement may be made a drain-route on the existing outer wall facilities. In this study, the numerical computations were carried out to predict the circulation of harbor waters and the tidal exchange through the drain-rout in the polluted harbor(Samchonpo-guhang) located at the east coast of South Sea. Computational models adopting FDM(Finite Difference Method) were used here and were already verified from the previous studies und ocean survey. As a result of this study, circulation and the tidal exchange at the harbor before and after introduction of drain-route were assessed.