• Journal of Environmental Science International
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• v.23 no.3
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• pp.409-431
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• 2014

In this study, the characteristics in the simulation of high-resolution coastal weather, i.e. sea surface wind (SSW) and significant wave height (SWH), were studied in a southeastern coastal region of Korea using the WRF and SWAN models. This analyses was performed based on the effects of various input factors in the WRF and SWAN model during M-Case (moderate days with average 1.8 m SWH and $8.4ms^{-1}$ SSW) and R-Case (rough days with average 3.4 m SWH and $13.0ms^{-1}$ SSW) according to the strength of SSW and SWH. The effects of topography (TP), land cover (LC), and sea surface temperature (SST) for the simulation of SSW with the WRF model were somewhat high on v-component winds along the coastline and the adjacent sea of a more detailed grid simulation (333 m) during R-Case. The LC effect was apparent in all grid simulations during both cases regardless of the strength of SSW, whereas the TP effect had shown a difference (decrease or increase) of wind speed according to the strength of SSW (M-Case or R-Case). In addition, the effects of monthly mean currents (CR) and deepwater design waves (DW) for the simulation of SWH with the SWAN model predicted good agreement with observed SWH during R-Case compared to the M-Case. For example, the effects of CR and DW contributed to the increase of SWH during R-Case regardless of grid resolution, whereas the differences (decrease or increase) of SWH occurred according to each effect (CR or DW) during M-Case.

• Fisheries and Aquatic Sciences
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• v.3 no.2
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• pp.97-110
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• 2000

To investigate characteristics of water masses and current structures around Noto Peninsula located in south-east coastal region of the East Sea, observation results of CREAMS (Circulations Research of the East Asian Marginal Seas) cruise and data report of oceanographic observation (Japan Meteorological Agency) in June, 1995 and 1996 were used. Water mass showing characteristics of Tsushima Warm Current (TWC) exists over the continental shelf. The depth is shallower than 200m and its width and thickness are 190km and 200m, respectively. Minimum level of dissolved oxygen occurred at the layers of maximum salinity. In the current structure, a noteworthy phenomenon is that the positions of the high-salinity water (more than 34.6 psu) match well with the distributions of the southwestward flow. In June of 1995 and June of 1996, a southwestward flow were separated into two parts along line C and line G. Current directions derived from the temperature and salinity match well with the distributions of the geostrophic currents in the vertical sections. The isothermal lines and the isohaline, which exist horizontally along the coastal area of the Japan, change abruptly at the frontal area of the Noto Peninsula, then turn toward the center of the East Sea. The dynamic depth anomalies centering around the region far northwest of the Noto Peninsula were relatively high, compared to those of other regions. The isopycnic surface (sigma-t, 25.8) existed near the surface in the central part of the East Sea, but, at the depth of 100m, the isopycnic surface was found in the coastal waters.

• 한국해양학회지
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• v.20 no.3
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• pp.1-5
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• 1985

Seasonal variations of heat content in the neighbouring seas of Korea are estimated from the bimonthly normals of seawater temperature in the upper 300m for 15 years (1961~1975) at 192 stations. The heat is seasonally stored mainly in the upper 100m layer in the East Sea and in the whole water column in the West and South Seas of Korea. The annual range of heat content changes in the West Sea is almost the same as that in the East Sea. The annual phase of heat content variation lags behind that of sea surface temperature variation by one to three months. Due to the seasonal advections of heat by currents and winds, the annual amplitude of heat storage rate in the neighbouring seas of Korea is much larger than that of incoming radiation.

• 한국해양학회지
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• v.9 no.2
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• pp.1-9
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• 1974

The vertical distribution and diurnal migration of Evadne nordmanii has been studied at different stations in the Irish Sea. There are many reports that the migrations of planktonic animals tend to be hampered by thermoclines and haloclines. Physical and chemical factors were compared with vertical distribution and diurnal migrations of the animal. Evadne must be essentially an epiplanktonic form with the ability to endure strong light intensity. The animals generally migrated to the very surface layer from their shallow day strata with the decreased of light intensity. During the night their distribution seems rather random or even throughout all the layers, with a tendency to concentrate at the bottom layers, when the water was homogeneous physically and chemically. E. nordmanii may penetrate minor thermoclines and haloclines, but they may avoid chemically distinct waters or possibly currents.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.2
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• pp.67-85
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• 2007

A three-dimensional hydrodynamic model with the fine grid is applied to simulate the barotropic tides, tidal currents, residual currents and salinity dispersions in the Yellow Sea and the East China Sea. Data inputs include seasonal hydrography, mean wind and river input, and oceanic tides. Computed tidal distributions of four major tides($M_2,\;S_2,\;K_1$ and $O_1$) are presented and results are in good agreement with the observations in the domain. The model reproduces well the tidal charts. The tidal residual current is relatively strong around west coast of Korea including the Cheju Island and southern coast of China. The current by $M_2$ has a maximum speed of 10 cm/s in the vicinity of Cheju Island with a anti-clockwise circulation in the Yellow Sea. General tendency of the current, however, is to flow eastward in the South Sea. Surface residual current simulated with $M_2$ and with $M_2+S_2+K_1+O_1$ tidal forcing shows slightly different patterns in the East China Sea. The model shows that the southerly wind reduces the southward current created by freshwater discharge. In summer during high runoff(mean discharge about $50,000\;m^3/s$ of Yangtze), low salinity plume-like structure(with S < 30.0 psu) extending some 160 km toward the northeast and Changjiang Diluted Water(CDW), below salinity 26 psu, was found within about 95 km. The offshore dispersion of the Changjiang outflow water is enhanced by the prevailing southerly wind. It is estimated that the inertia of the river discharge cannot exclusively reach the around sea of Cheju Island. It is noted that spatial and temporal distribution of salinity and the other materials are controlled by mixture of Changjiang discharge, prevailing wind, advection by flowing warm current and tidal current.

• Korean Journal of Remote Sensing
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• v.26 no.3
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• pp.297-304
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• 2010

Since the change in Doppler centroid according to moving targets brings alteration to the phase in azimuth differential signals of synthetic aperture radar (SAR) data, one can measure the velocity of the moving targets using this effect. In this study, we will investigate theoretically measuring the velocity of an object from azimuth differential signals by using range compressed data which is the interim outcome of treatment from the simulated SAR raw data of moving targets on the background of sea clutter. Also, it will provide evaluation for the elements that affect the estimation error of velocity from a single SAR sensor. By making RADARSAT-1 simulated image as a specific case, the research includes comparisons for the means of velocity measurement classified by the directions of movement in the four following cases. 1. A case of a single target without currents, 2. A case of a single target with tidal currents of 0.5 m/s, 1 m/s, and 3 m/s, 3. A case of two targets on a same azimuth line moving in a same direction and velocity, 4. A case of a single target contiguous to land where radar backscatter is strong. As a result, when two moving targets exist in SAR image outside the range of approximately 256 pixels, the velocity of the object can be measured with high accuracy. However, when other moving targets exist in the range of approximately 128 pixels or when the target was contiguous to the land of strong backscatter coefficient (NRCS: normalized radar cross section), the estimated velocity was in error by 10% at the maximum. This is because in the process of assuming the target's location, an error occurs due to the differential signals affected by other scatterers.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.1
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• pp.10-21
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• 2009

Muan Bay has extensively undertaken artificial influences through a series of construction of dams and dykes nearby resulting in a substantial increase in highest high water level. To unravel sedimentary responses to the water level rise, we collected a number of surface sediment samples and hydrodynamic data from in-situ observations of tidal currents in Muan Bay in 1998 and 2007. Comparison of the data between 1998 and 2007 shows that the relative content of coarse fractions, sand and gravel, in the sediment samples has increased with a decreased mean size, on average, from 6.2 to 5.8${\phi}$ at the expense of silt contents. Such a coarsening trend, which is more evident around high water level, particularly on the tidal flats of Dongam-ri, Guro-ri and Aphae-do, is most likely attributable to rising water level. On the other hand, an increase of fine fractions locally in the western entrance of the bay can be explained with changes in characteristics of tidal currents imposed by construction of bridges therein, such as decreased velocities and varied direction and phase of the tidal currents.

• Ocean and Polar Research
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• v.38 no.2
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• pp.161-169
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• 2016

The interannual variability of the water masses was analyzed from the CTD data measured in the tropical northwestern Pacific from 2006 to 2014. There are two typical water masses NPTW and NPIW that reveal the interannual variability in the survey area, in addition to two other water masses; the surface water mass TSW with a large seasonal variability and the deep water mass AACDW with a constant temperature-salinity characteristic at the depths deeper than 2,000 meters. In 2012 and 2014 NPTW was the most widely extended horizontally and thicker than 100 meters vertically, which was found over the entire survey area. However, NPTW was reduced and became much narrower in 2009 than in the other years. NPIW seemed to expand southwards from the north of $21^{\circ}N$ to $15^{\circ}N$ in 2008 and in 2012, which showed the salinity minimum in 2013 (< 34.15 psu). The sea surface height estimated by Absolute Dynamic Topography (ADT) approximately along $135^{\circ}E$ section showed the high peaks (> $1.45dyn{\cdot}m$) between $16^{\circ}N$ and $18^{\circ}N$ during the periods between 2007 and 2009 and between 2012 and 2013; the former peak lasted wider and longer in latitude and time (about three times) than the latter. The vertical section of the geostrophic currents in the upper 1,000 meters shows that there was a mesoscale pattern of repeated eastward and westward flows a few times in some years (2010 and 2014), which seemed to disappear in some other years (2008 and 2012); the former was closely related to the mesoscale eddies and the latter implied the pattern with the permanent currents. The persistent eastward flow between $17^{\circ}N$ and $19^{\circ}N$ seems to be related to the Subtropical Countercurrent (STCC).

• Fisheries and Aquatic Sciences
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• v.10 no.2
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• pp.86-92
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• 2007

Adult Dungeness crabs are restricted primarily in the lower part of Glacier Bay, Alaska, but the interaction of larval dispersion and adult distribution is unknown. To understand the larval occurrence in the upper part of Glacier Bay, Dungeness crab larvae, sea surface temperature (SST), and sea surface salinity (SSS) were collected at 16 near-shore and 12 mid-channel stations in Glacier Bay, southeastern Alaska during six sampling periods from March through August 2000. Each station was visited from one to five times during the entire sampling period. Geographic Information System (GIS) was used to contour SST and SSS distribution in Glacier Bay. Seven to 27 stations were visited during each sampling period. Most larvae (85% were zoeae I) occurred during May 31 to June 14, 2000. Larval density varied from none to $51.4\;100\;m^{-3}$ between stations. A few later stage larvae occurred during later sampling periods. Overall, no relationship between larval densities, and SSS, and SST existed. Larvae occurring in the upper bay were probably transported by tidal currents from the lower bay; adult Dungeness crabs in Glacier Bay have a relatively high density near the mouth of the bay but decrease sharply around 40km north of the mouth. The lack of adult crabs in the upper 60km of the bay may be related to lower salinity, resulting in sharp haloclines, or colder temperatures which are not conducive to survival or growth of either larvae or adults.

• Journal of the korean society of oceanography
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• v.37 no.3
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• pp.169-177
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• 2002

An eddy-resolving free-surface primitive-equation model with nonlinear terrain-following coordinates is established to study the exchange of water masses among the Asian marginal seas and their adjacent waters. A curvilinear coordinate system is used to generate the horizontal grid with a variable resolution for the regional oceans from $5^{\circ}$S to $45^{\circ}$N and $100^{\circ}$E to $155^{\circ}$E. The higher resolution region has about a 10 km by 10 km grid covering the complex geometry of the coastal marginal seas, while the lower resolution region has about a 30 km by 30 km grid covering the eastern Pacific. The model is initialized by the Levitus annual climitology and forced by the monthly mean air-sea fluxes of momentum, heat, and freshwater derived from the Comprehensive Ocean-Atmosphere Data Set. High-resolution and low-viscosity are identified as the key factors for a better representation of the exchange of waters through narrow straits and passages between the marginal seas and their adjacent waters. The dynamics of the loop currents and eddies in the South China Sea and Celebes Sea are examined in detail. It has found that the anticyclonic loop and detached eddies from the Kuroshio through the Luzon Strait play an important role in transporting warm and salty water into the South China Sea, while the cyclonic circulation of the Mindanao Current in the Celebes Sea plays a role in contributing cold water to the Indonesian throughflow. The deep undercurrent of the western Pacific is shown to provide fresher water to the South China Sea and Celebes Sea. These modeling results suggest that the exchange processes via the narrow straits and passages are of fundamental importance to the maintenance of water masses for the marginal sea region.