• 한국해양학회지
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• v.28 no.1
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• pp.24-34
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• 1993

In order to study the seasonal characteristics of species composition and abundance, zooplankton samples were collected from April 1987 to June 1988 with bimonthly intervals in the Mid-Eastern part of the Yellow sea. Among the 24 species of 18 genera occurred in this study area, 17 species are copepods. Noctiluca scintillant has greatly influenced on the distribution of the zooplankton in the coastal area and some copepods may be excluded by its great occurrence. the seasonal variation of abundance of copepods accounting for 30-63.4% of total zooplankton were more varied among stations in the coastal area than in the offshore. It suggests that environmental factors are more variable in the coastal area than in the offshore. In the Copepod community, Acartia omorii, Paracalanus parvus and Corycaeus affinis were predominant in April and June, from August to December and in December, respectively. Sagita enflata as a Kuroshio indicator species, occurred in the study area from August to December. The great occurrence of warm water species, Doliolum sp. in October and the occurrence of Sagitta enflata from August to December suggested that there is a influx of the tributaries of Kuroshio current into the study area. It appeared that the seasonal characteristics of species composition and abundance of zooplankton were affected by the seasonal variation of water mass.

• Journal of Environmental Impact Assessment
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• v.11 no.1
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• pp.51-66
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• 2002

The purpose of this study is to analyze the geomorphological environment changes of tidal flat in the Cheonsu Bay. Especially, it centers on the changes in the sedimentary environment using remote sensing data. Multi-temporal Landsat data and topographic maps were used in this study. The results are summarized as follows: the tidal flat of Cheonsu Bay changes in many ways depending on the direction of the tidal current. In the neighborhood of Ganwoldo, the scale of the tidal flat has continuously been expanded due to the superiority of sedimentation after a tide embankment was built. When we analyzed the grain size of sediments and implemented in-situ field survey, it was found that the innermost part of the bay consists of a mud flat, with the midway part mixed flat, and the nearest part to the sea sand flat. On the other hand, in the neighborhood of Seomot isle and its beach, sedimentation is superior in the eastern part whereas erosion is superior in the western part. In other words, the western coast of the beach is contacted with the open seas and under much influence of ocean wave. The eastern coast is placed at the entrance of the bay and has sand bar and tidal flat developed due to submarine deposits that are accumulated on the sea floor by the tidal current. In conclusions, remote sensing methods can be effectively applied for quantitative analysis of geomorphological changes in tidal flat, and it is expected that the proposed schemes can be applied to another geomorphological environments such as beach, sand dune, and sand wave.

• Asia-Pacific Journal of Atmospheric Sciences
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• v.54 no.4
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• pp.545-561
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• 2018

Over the North East Asia, extreme anomalous precipitation were observed in 2013 and 2014. During 2013 summer the precipitation was found to be higher (two standard deviation) than the climatological mean of the region; whereas during 2014, which was a borderline El Ni?o year, precipitation was found to be lower (one standard deviation). To understand the differences of these two anomalous years the Global/Regional Integrated Model system (GRIMs) has been used. The study found that low landsurface temperature and high sea-surface temperature over ocean caused a smaller land-sea contrast of surface temperature between East Asia and North West Pacific Ocean in 2014, which could have caused an eastward shift of mean monsoon circulation in that year compared to the circulation in 2013. Due to a change in the lower level circulation and wind field over East Asia the evaporation and moisture transport patterns became very different in those two years. In 2013, this study found high latent heat flux over Eastern China, which implies an increased surface evaporation over that region, and the moisture transported to the north by the mean monsoon circulation; whereas, there was no correlated transport of moisture to the North East Asia during 2014. The precipitable water over North East Asia has a stronger correlation with the latent heat flux over southern land region than that from Ocean region in the eastern side in both the years. A new approach is proposed to estimate the sub-grid scale hydrometeors from GRIMs, overestimated in the existing model.

• Journal of the Korean earth science society
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• v.43 no.6
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• pp.712-736
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• 2022

To understand the characteristics of low-level clouds (CLs), environmental variables are composited on each CL using individual surface observations and six-hourly upper-air meteorologies around the globe. Individual CLs has its own distinct environmental conditions. Over the eastern subtropical and western North Pacific Ocean in JJA, stratocumulus (CL5) has a colder sea surface temperature (SST), stronger and lower inversion, and more low-level cloud amount (LCA) than the climatology whereas cumulus (CL12) has the opposite characteristics. Over the eastern subtropical Pacific, CL5 and CL12 are influenced by cold and warm advection within the PBL, respectively but have similar cold advection over the western North Pacific. This indicates that the fundamental physical process distinguishing CL5 and CL12 is not the horizontal temperature advection but the interaction with the underlying sea surface, i.e., the deepening-decoupling of PBL and the positive feedback between shortwave radiation and SST. Over the western North Pacific during JJA, sky-obscuring fog (CL11), no low-level cloud (CL0), and fair weather stratus (CL6) are associated with anomalous warm advection, surface-based inversion, mean upward flow, and moist mid-troposphere with the strongest anomalies for CL11 followed by CL0. Over the western North Pacific during DJF, bad weather stratus (CL7) occurs in the warm front of the extratropical cyclone with anomalous upward flow while cumulonimbus (CL39) occurs on the rear side of the cold front with anomalous downward flow. Over the tropical oceans, CL7 has strong positive (negative) anomalies of temperature in the upper troposphere (PBL), relative humidity, and surface wind speed in association with the mesoscale convective system while CL12 has the opposite anomalies and CL39 is in between.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.57 no.3
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• pp.262-277
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• 2024

The mid-eastern coast of Korea is located at the boundary between cold and warm currents, which causes changes in the distribution and composition of marine organisms in response to fluctuations in the marine environment. To understand the seasonal changes in the seaweed community, we investigated its species composition, biomass, coverage, and frequency from November 2022 to August 2023. A total of 45 species (7 green, 18 brown, and 20 red algae) were found in the study area. In the intertidal zone, the number of species decreased from autumn to summer; the biomass peaked during winter (471.94 g wet weight m^-2). Seaweed groups were the dominant functional groups, which were coarsely branched, filamentous, and sheet-like during autumn, winter, spring, and summer. The morpho-functional group was dominated by turf species. In the subtidal zone, the number of species increased during autumn to spring, whereas the biomass peaked during spring (655.27 g wet weight m^-2). The functional group was dominated by coarsely branched species throughout all four seasons, whereas the morpho-functional group was dominated by canopy species. Consequently, changes in the biomass of brown and red algae are recognized as key drivers of seasonal changes in seaweed communities.

• 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.

• Journal of the Mineralogical Society of Korea
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• v.29 no.1
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• pp.1-10
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• 2016

We studied the heavy minerals in 46 surface sediments collected from the Central Yellow Sea Mud (CYSM) to characterize the type, abundance, mineralogical properties and distribution pattern using the stereo-microscopy, field-Emission scanning electron microscopy (FE SEM) and chemical analysis through the energy dispersive spectrometer (EDS). Heavy mineral assemblages are primarily composed of epidote group, amphibole group, garnet group, zircon, rutile and sphene in descending order. Epidote group and amphibole group minerals account for more than 50% of total heavy minerals. The minerals in epidote group, amphibole group and garnet group in studied area are epidote, edenite and almandine, respectively. When we divided the CYSM into two regions by $124^{\circ}E$, the eastern region contain higher contents of epidote and (zircon + rutile), which are more resistant to weathering but lower of amphibole, which is less resistant to weathering than the western region. Based on this results, it is possible to estimate that the eastern region sediments are transported for a long distance while western region sediments are transported for a short distance from the source area. In the future, the additional study on the heavy minerals in river sediments flowing into the Yellow Sea and much more samples for marine sediments must be carried out to interpret exactly the provenance and sedimentation process.

• Journal of the Korean Society for Marine Environment & Energy
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• v.8 no.3
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• pp.140-147
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• 2005

We investigated the interactions between coastal waters of the Yeongil Bay, Korea, and oceanic waters of the Eastern Sea, as wet 1 as the development mechanism of vertical circulation currents in the bay. The oceanic waters of the bay have an average water temperature of $12.2{\sim}18.4^{\circ}C$ and salinity of $33.32{\sim}34.43$ PSU. Results of spectral analysis have shown that the period of revolution between oceanic and coastal waters is about 0.84-0.91 years in the surface waters and 1.84 years in the bottom layer. The wind direction in the bay shifts between SW and NE, with the main wind direction being SW during the winter period, and water mass movement is influenced by such seasonal variations in wind direction. Vertical circulation currents in the bay are structured by two phenomena: the surface riverine outflow layer from the Hyeong-san River into the open sea and the bottom oceanic inflow layer with high-temperature and salinity into the bay. These phenomena start the spring when the water mass is stable and become stronger in the summer when the surface cold water develops over a 10-day period. Consequently, tidal currents have little influence in the bay; rather, these vertical and horizontal circulation currents play an important role in the transport of the pollutant load from the inner bay to the open sea.

• The Korean Journal of Quaternary Research
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• v.7 no.1
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• pp.1-26
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• 1993

The estimation of the Last Interglacial sea level was made by using the thalassostatic terrace which had been developed in the lower reach of Namdaechon river in Kangneung, eastern coastal area of Korea. The fluvial terraces, which have been developed since late Pleistocene, were investigated. The main findings were as follows; 1) That Kangneung terrace I had been formed in the climax period of the Last Interglacial (Oxygen isotope stage 5e) was revealed. It was estimated that Kangneung terrace II had been formed during a certain warmer period between the climax period of the Last Interglacial and the early Last Glacial(probably Oxygen isotope stage 5c or 5a). 2) Being judged from the relative heights of the Kangneung terrace I and II, the sea levels of the formation periods of these terraces were estimated to have been relatively 17~20m and l0m higher than the present sea level, respectively. 3) The formation periods of the Wangsan terrace I and II were supposed to be the early and late Last Glacial respectively, being judged from the following 3 details ; a) the characteristics of the terrace deposits, b) the relation Wangsan terrace II to the buried valley floor, and c) the cross phenomena of the above two terraces to the Kangneung terraces. 4) The formation period of the pseudogleyed red soil in the Kangneung terrace I was estimated to be the middle or late period of the Last Interglacial.

• The Korean Journal of Quaternary Research
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• v.7 no.1
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• pp.69-91
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• 1993

A total of 76 surface sediment samples, collected from the Korean west coast and the eastern Yellow Sea areas, were analyzed for their elemental composition in order to understand the geochemical characteristics of these deposits. The analyzed elements included 9 major elements (Al, Fe, Na, K, Mg, Ca, Ti, P, Mn), 8 minor elements (Sr, Ba, V, Cr, Co, Ni, Cu, Zn), organic carbon and calcium carbonate. Contents of most analyzed elements, excluding K and Ba, were generally low compared to those of average crust. Contents of most elements, except K and Ca, also correlated with sediment grain size, though the degree of relationship varied widely from one element to another. For fine-grained sediments, a distinction could be made between those in the central Yellow Sea and those in the Keum Estuary based on their characteristic elemental composition: the former were rich in Fe, Na, K, Mg, Ca and V, and the latter in Mn, Co and Ni. The element/aluminium ratios, on the other hand, showed that the central Yellow Sea muds were enriched in Fe, Mg, V, Ni, Cu and Zn and depleted in K, Mn, Ba and Sr relative to the mud located near the Korean Peninsula. Based on the analysis of these results, as well as of the influences of particular mineral phases or pollution effects, we could suggest geochemical criteria which can be used in distinguishing muds from the two different sources, the Keum River and the Yellow River: the former by the higher Mn content and the latter by the higher Mg and V contents, relative to each other.