• Title/Summary/Keyword: 해저전선

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An Oceanic Front : The Formation of Tidal Fronts with Its Microscale Structure Evolution (해양전선 : 조석전선의 형성 및 그 미세구조의 전개 과정)

  • Yi-Gn Noh
    • International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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    • v.21 no.1
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    • pp.17-30
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    • 1993
  • The basic processes responsible for the generation of oceanic fronts were reviewed. In particular the process of a shelf sea front produced by tidal stirring was identified from the one dimensional model of the water column in the coastal area, which incorporates the microscale process for the formation of a tidal front. Also a new criterion to predict its location was suggested. The time evolutions of the distributions of density and turbulent kinetic energy calculated from the model show that the criterion for the formation of a thermocline can be predicted as $R{\delta}^4$~ constant for large $\delta$ ($\delta$>0.5), but the dependence on $\delta$ decreases as $\delta$ goes to O, where $R=H^4Q/{K_b}^3$,{\;}{\delta}=1-Do/H$, Q is the buoyancy flux at the surface, $K_b$ is the eddy diffusivity maintained at the bottom and Do is the depth of a thermocline in the absence of bottom mixing. The depth of a thermocline was found to decrease as the bottom mixing increases for a given value of Do. The results were interpreted in comparison with the previous studies.

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Thermohaline Structure of the Shelf Front in the Korea Strait in Early Winter (초겨울 大韓海峽에서 形成되는 淺海前線의 構造)

  • Lee, Jae Chul;Na, Jung Yul;Chang, Sun-Duck
    • 한국해양학회지
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    • v.19 no.1
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    • pp.56-67
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    • 1984
  • Mesoscale thermohaline structures of the meandering front in the Korea Strait during November 1976, 1980 and 1982 are studied by means of closely spaced oceanographic observations and the satellite infrared images. Strong thermal and salinity fronts coincide each other and show a wavelike meander motion with wavelengths of 40-60km and amplitudes of, 15-20km. Salinity minimum band of less than 33.0 is found along the onshore edge of the front. Width of the frontal zone corresponds approximately to the internal radius of deformation (R=5-10km) and the slope of density interface is confined to about 2R. A series of satellite infrared images with the interval of 4-5 days show a noticeable growth of frontal meander over the flat shelf west of the Korea Strait. Possible mechanisms of frontal meander and its growth are discussed.

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Water Masses and Frontal Structures in Winter in the Northern East China Sea (동중국해 북부해역의 겨울철 수계와 전선구조)

  • 손영태;이상호;이재철;김정창
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.8 no.3
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    • pp.327-339
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    • 2003
  • During the winter in February 1998, January and April 1999, interdisciplinary research was conducted in a large area including the South Sea of Korea and northern East China Sea to examine distribution and structure. Water masses identified from the observed data are Warm Water originated from Tsushima Warm Current, Yellow Sea Cold Water (Northern or Central Cold Water) and Korean Southern Sea Cold Water. In the southern Yellow Sea, Warm Water originated from Tsushima Warm Current, flowing into the Cheju Strait after turning around the western Cheju Island, makes a front of '┍' shape, which is bounded by the Yellow Sea Central Cold Water in the southern part of Daeheuksan Island and by the Yellow Sea Northern Cold Water in the eastern part of the Yangtze Bank. This front changes its corner shape and position with strength of the warm water extension toward northwestern Yellow Sea. The position and structure of the fronts off the southwestern tip of the Korean peninsular and near the Yangtze Bank varies with observation period. In the front in the South Sea of Korea, cold coastal water which if formed independently due to local cooling, ,sinks along the sloping bottom. We explained the processes of variations in the distribution and structure of these winter fronts in terms of up-wind and down-wind flow by the seasonal monsoon, heat budget through the sea surface and density difference across the fronts.

Structure of Shelf Front and Distribution of Plankotns in the Eastern Part of the Yellow Sea (황해동부의 대륙붕전선의 구조와 부유생물의 분포)

  • CHO Kyu Dae;HONG Seong Yoon;KIM Hee Joon;YANG Yong-Rhim
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.16 no.4
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    • pp.316-329
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    • 1983
  • The formation and structure of the shelf front in the eastern part of the Yellow Sea are studied on the basis of oceanographic data collected in August, 1982 and February, 1983. This paper also describes the distribution of planktonic organisms of the shelf front. In summer the shelf front is formed in the area ($126^{\circ}02^'E-126^{\circ}05^'E$) ca. 20 miles from the shore at the depths of 15-25 m. in winter, however, no distinct shelf front is formed. Based on the cluster analysis of surface phytoplankton the species composition shaws a discontinuous pattern in the vicinity of the shelf front in summer, 1982. A similar trend is observed in distribution of some copepod species in winter, l983.

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High-Current Time-Lapse Electrical Imaging in Marine Sediments Area (해성퇴적층 하부지반 대전류 time-lapse 전기탐사)

  • Jung, Hyun-Key;Geo, Dong-Kweon Lee
    • 한국지구물리탐사학회:학술대회논문집
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    • 2006.06a
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    • pp.109-112
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    • 2006
  • Successful field test results for high-current time-lapse electrical imaging in marine sediments area are discussed. Because field trial by commercially available equipments were failed, self-developed system which supports transmitting current up to 5 ampere was used. Some weak zones due to local fractures were detected, but the weak zone effect in this area by time-lapse measurements from sea level change was minor.

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A Study of the Hydrographic Conditions and Tidal Front on the Northern Coastal Area of Cheju Island (제주도 북부연안역의 해황과 조석전선 특성)

  • Kim Sang-Hyun;RHO Hong-Kil;CHOI Chan-Moon
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.31 no.3
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    • pp.437-446
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    • 1998
  • The general pattern of the hydrographic conditions and tidal front of the northern coastal area of Cheju Island is investigated using the CTD observation data and a stratification parameter V ($J/m^3$) in $1991\~1993$. 1. The sea water of the northern coastal area of Cheju Island has a lower temperature and higher salinity than that in the central area of the Strait, and local temperature and salinity fronts appears frequently around this area. It seems that they are caused by the upwelling and the tidal front as well as a local topography. 2. A saddle-like distribution of temperature and salinity is formed in the Cheju Strait almost every month with relation to mixing of the different water masses. 3. In the northern coastal area of Cheju Island the stratification parameter V ($J/m^3$) was ranged from 8.4 to 209.8 $J/m^3$ in June, 201.9 to 634.9 $J/m^3$ in August, 0.18 to 680 $J/m^3$ in September, and $2.7\~462\;J/m^3$ in October, respectively. The tidal front was often formed around the place where the horizontal variation of the depth is very large and the potential energy with 10$J/m^3$ appears roughly along 50 m isobath.

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