East Korea Research Articles

A Study on the Community Structure of Subtidal Marine Algae in Kijang, Korea

A subtidal marine benthic algal vegetation at Kijang, the southern east of Korea was investigated to clarify the community structure and the pattern of geographical distribution by a quadrat method along a transect line between February 2006 and January 2007. Total 59 species including 6 of green algae, 14 of brown algae, 39 of red algae were collected and identified. Among these species, 14 species were found throughout the year. Annual mean biomass in wet weight of total vegetation, maximum biomass was recorded in winter and spring seasons, and decreased in summer season. Dominant species was Prionits cornea in terms of biomass, and subdominant species were Phycodrys fimbriata and Gelidium amansii. Coarsely branched form was the most abundant accounting 64.4% of the total value. Seasonal variations in algal bio- mass were principally linked to fluctuations in biomass of coarsely branched and thick leathery form algae. The R/P, C/P and (R+C)/P value reflection flora characteristics were 2.79, 0.43 and 3.21, respectively. Two groups produced by cluster analysis, one including sites Duho, Dongbaek and the other including sites Seoam, Mundong, showed meaningful difference in similarity, each other. In conclusion, the number of marine algae species in Kijang was reduced comparing with the previous studies.

Sculpture of pollen grains of Quercus L. from the holocene of the south of the Sea of Japan

Fossil pollen grains of Quercus L. were studied with application of an EVO 40 scanning electron microscope. The material came from Holocene core samples from deep water zone of the south of the Sea of Japan and shelf zone of East Korea Bay. The pollen grains were obtained from three radiocarbon-dated palynological assemblages. Six types of fossil pollen grains were revealed: four of them were assigned to deciduous oaks and two were assigned to evergreen oaks.

Cenozoic tectonic evolution of Asia: A preliminary synthesis

Asia has been a major testing ground for various competing models of continental deformation due to its relatively well-understood plate boundary conditions in the Cenozoic, exceptional exposure of active structures, and strain distribution, and widespread syn-collisional igneous activity as a proxy for the thermal state of the mantle and crust. Two Cenozoic orogens dominate the continent: the Himalayan–Tibetan orogen in the east induced by the India–Asia collision and the Turkish–Iranian–Caucasus orogen in the west induced by the Arabia–Asia collision. The development of the two orogens was accomplished by shortening in the early stage followed by strike-slip faulting and extension in the late stage. In the Himalayan–Tibetan orogen, shortening across two discrete thrust belts at 55–30 Ma in southern and northern Tibet created a large intracontinental basin (the Paleo-Qaidam basin) in between. Subsequent crustal thickening and a possible thermal event in the mantle (e.g., convective removal of central Tibetan mantle lithosphere) may have raised the elevation of this early intra-plateau basin up to ~ 2–3 km to its current height. Collision between India and Asia also caused lateral extrusion of southeast Asia between 32 Ma and 17 Ma. The latest stage of the India–Asia collision was expressed by north-trending rifting and the development of trench-facing V-shaped conjugate strike-slip faults in central Mongolia, central Tibet, eastern Afghanistan and southeast Asia. In the Turkish–Iranian–Caucasus orogen, early crustal thickening in the orogenic interior began at or prior to 30–20 Ma. This style of deformation was replaced by strike-slip faulting at ~ 15–5 Ma associated with further northward penetration of Arabia into Asia, westward extrusion of the Anatolia/Turkey block, and rapid extension across the Sea of Crete and Sea of Aegean. The late stage extension in both orogens was locally related to extensional core-complex development. The continental-margin extension of east Asia was developed in two stages: initially in a widely distributed zone that has an east-west width of 500–800 km during 65–35 Ma, which was followed by localized extension and opening of back-arc basins associated with the development of spreading centers at 32–17 Ma (e.g., Japan Sea or East Korea Sea, Bohai Bay, and South China Sea). Opening of the back-arc basins could be induced by (1) rapid eastward migration of the western Pacific trench system or (2) oblique subduction of Pacific plate beneath Asia that had produced a series of en echelon right-slip primary shear zones linking with back-arc spreading centers oriented obliquely to the strike of the nearby trench. Since ~ 15 Ma, the eastern margin of Asia became contractional in the east–west direction, as indicated by the collapse of back-arc basins in the western Pacific and the development of fold-thrust belts along the eastern continental margin. Coeval with the contraction is widespread east–west extension in Siberia, North China, and the Tibetan plateau. The above observations can be explained by a change in boundary condition along the eastern margin of Asia that allowed the thickened Asian continent to spread eastward, causing east-west extension in its trailing edge and east-west compression in its leading edge. In west Asia, continental-margin extension started at about 25–20 Ma in the Aegean and Cretan regions, which was associated with a rapid southward retreat of the Hellenic arc. The complex evolution of Cenozoic deformation in Asia may be explained by a combined effect of temporal changes in plate boundary conditions, thermal evolution of the upper mantle perturbed by collisional tectonics, and the built-up of gravitational energy through crustal thickening and thermal heating. Although the past research in Asia has treated the India–Asia and Arabia–Asia convergence as separate collisional processes, their interaction may have controlled the far-field Cenozoic deformation in Asia. The most pronounced result of this interaction is the creation of a northeast-trending 300–400-km wide and > 1500-km long zone of northwest-striking right-slip faults, which extends from the Zagros thrust belt in the south to western Mongolia in the north and links with the active Tian Shan and Altai Shan intracontinental orogens. Cenozoic deformation and coeval igneous activity spatially overlap with one another in the Himalayan–Tibetan and Turkish–Iranian–Caucasus orogens. A large Cenozoic magmatic gap exists between Tibet in the south and Mongolia in the north where Cenozoic deformation has not been associated with any coeval igneous activity. Finally, Cenozoic igneous activity is always associated with Jurassic–Cretaceous magmatic arcs, suggesting a causal relationship between the early arc magmatism and later syn-collisional magmatism.

To Be or Not To Be: South Korea's East Asia Security Strategy and the Unification Quandary

South Korea's Lee Myong-bak government has adopted a new East Asia strategy to cope with the changing security environment on the Korean peninsula, as well as in Northeast Asia. Departing from its traditional dependence on the bilateral alliance with the United States, South Korea now seeks a diversified strategy which includes upgrading the alliance with the US to a ‘strategic alliance’, developing a ‘strategic cooperative partnership' with China and promoting a multilateral security mechanism in Northeast Asia. Although it is not clear how South Korea will handle the contradictory elements and the complexity of the new strategy, it provides a more realistic approach to dealing with a possible North Korean contingency and the question of Korean unification, which should and will eventually be shaped by the two Koreas' choices.

Circulation features in the Japan/East Sea related to statistically obtained wind patterns in the warm season

A response of the circulation in the Japan/East Sea (JES) to different kinds of wind forcing is studied, with the emphasis on the warm season, using a primitive equation oceanic model. Wind forcing is based on typical patterns obtained from complex empirical orthogonal functions of 1°-gridded NCEP/NCAR 6 h winds for 1998–2005. These patterns are distinguished by a prevailing wind direction. Northwestern wind and strong cyclonic (C) curl prevail in winter, while a variety of patterns occur in the warm season, differing in the wind direction and curl. Three model runs are performed to examine the circulation in response to a prevailing C wind stress curl or an alternating C and anticyclonic (AC) curl or a strong C curl in the warm season. The simulated features are consistent with the observational evidence, in particular with thermal fronts and frequent eddy locations derived from multi-year infrared satellite imagery. The simulated C circulation intensifies and the subarctic region extends southward with the strengthening of a summer C wind stress curl over the JES. Variability of Subarctic Front (SF) in the western JES (between 130°E and 133°E) is strongly affected by summer wind stress curl. Forcing by an AC curl tends to shift SF northward, while SF shifts to the south under the forcing by a C curl, reaching the southern Ulleung Basin in the case of the strong C curl. In the northwestern JES (off Peter the Great Bay, Russia, and North Korea), the SF northwestern branch (NWSF) is simulated. It is a known feature in autumn and early winter and can also occur in the warm season. The simulation results suggest an AC wind stress curl as the forcing of the formation of the NWSF in the warm season. The Siberia Seamount and sharply bending coastline near Peter the Great Bay facilitate partial separation of the Primorye (Liman) Current from the coast. The wind stress curl can be an additional forcing of the Tsushima Warm Current (TWC) branching off the Korea Strait to the East Korea Warm Current (EKWC) and the offshore branch (OB). In the warm season, the simulated TWC bifurcation occurs farther north, the EKWC is strong, and the OB is weak under the forcing of the AC wind stress curl. The EKWC is weak and the OB is strong under the forcing of the strong C wind stress curl.

Contrast in life histories of exploited fishes and ecosystem structures in coastal waters off west Canada and east Korea

By reviewing the history of fishery exploitation in the coastal waters of west Canada and east Korea, related with contrasting life history strategies of the dominant species, the fishery management challenges that each country would face in the upcoming decades were outlined. In the ecosystem of the Canadian western coastal waters, the dominant oceanographic feature is the coastal upwelling domain off the west coast of Vancouver Island, the northernmost extent of the California Current System in the eastern North Pacific. In the marine ecosystem of the eastern coasts of Korea (the Japan/East Sea), a major oceanographic feature is the Tsushima Warm Current, a branch of the Kuroshio Current in the western North Pacific. Fishes in the Canadian ecosystem are dominated by demersal, long-lived species such as flatfish, rockfish, sablefish, and halibut. During summer, migratory pelagic species such as Pacific hake, Pacific salmon, and recently Pacific sardine, move into this area to feed. In the late 1970s, Canada declared jurisdiction for 200 miles from their coastline, and major fisheries species in Canadian waters have been managed with a quota system. The overall fishing intensity off the west coast of Vancouver Island has been relatively moderate compared to Korean waters. Fishes in the ecosystem of the eastern Korean waters are dominated by short-lived pelagic and demersal fish. Historically, Korea has shared marine resources in this area with neighbouring countries, but stock assessments and quotas have only recently (since the late-1990s) been implemented for some major species. In the Korean ecosystem, fisheries can be described as intensive, and many stocks have been rated as overfished. The two ecosystems responded differently to climate impacts such as regime shifts under different exploitation histories. In the future, both countries will face the challenge of global warming and subsequent impacts on ecosystems, necessitating developing adaptive fisheries management plans. The challenges will be contrasting for the two countries: Canada will need to conserve fish populations, while Korea will need to focus on rebuilding depleted fish populations.

MNCs' Offshore R & D Mandates and Host Countries' Locational Advantages

Offshore R & D by multinational corporations (MNCs) has increasingly involved the developing world in East Asia, initially Taiwan and Korea but more recently China and India. However, the R & D mandates of foreign R & D facilities in this region tend not to follow the paths of evolutionary models. To explain this phenomenon, this article presents a conceptual framework, essentially based on Dunning's eclectic paradigm, with a strong flavor of the evolutionary approach to technology, but which, in some cases, also allows for leapfrogging competition. In terms of empirical work, the article also explores the relationship between MNCs' overseas R & D mandates and the locational advantage of the host country by conducting case studies on flagship MNCs' R & D facilities in the information technology sector on both sides of the Taiwan Strait. The results show some interesting contrasts across the Taiwan Strait that run counter to the evolutionary perspective. There are grounds to suggest that such contrasts have much to do with the locational advantages Taiwan and China each possess. Further implications are drawn to enrich the current understanding of R & D internationalization.

동해 왕돌초 주변 해역의 동계와 하계 식물플랑크톤 군집 분포

Wangdol-cho, located 23 km offshore of Hupo in southwest of East Sea, is underwater rock floor, called to Wangdol-Am or Wangdol-Jam and has three tops as Mat-Jam, Middle-Jam and Set-Jam. The composition, abundance, diversity and community structure were investigated in winter and summer in 2002 around Wangdol-cho. The temperature around the Northwest and Southeast part of Wangdol-cho was influenced by the North Korea Cold Current (NKCC) and East Korea Warm Current (EKWC), respectively. Nutrient and chlorophyll-a concentration were higher at the top of Wangdol-cho than other area. A total of 41 genera and 78 species of phytoplankton were identified. The average cell abundance of phytoplankton in winter and summer were <TEX>$286{\times}10^3\;cells/m^3,\;432{\times}10^3\;cells/m^3$</TEX> respectively. The largest community was Bacillariophyta containing 52 taxa. The dominant species were Lauderia anulata and Coscinodiscus spp. which preferred cold water in winter. In contrast, warm water species such as Rhizosolenia stolterfothii and Ceratium spp. were dominant in summer. The average species diversity index of phytoplankton in winter was higher than that in summer. According to dominant species and standing crops, phytoplankton community resulted in a clear separation. One group was western area, which showed low density, and the other was eastern area, which showed the higher density. The abundance and species composition of phytoplankton. were affected by topological characteristics around Wangdol-cho.

The Impact of ASEAN+3 Trade Agreements on the South Asian Economy

Regional economic integration has been adopted as a strategy for development in different regions of the world in the 1980s following the formation of single market by the European Union and NAFTA by the North American countries. Though Asian countries have been slow to respond to the global trend of regionalism, however, over the past few years these countries have also recognized the potential of regional economic integration and have started taking steps to benefit from it. Several initiatives of broader economic integration are in progress to push the agenda of regional economic integration. Besides deepening the sub regional cooperation between its 10 member states, ASEAN is also negotiating with major East Asian countries, Japan, China and Korea to formulate a regional trade agreement. This would likely to have an impact on the other economies of the world. However, the impact of regional trade agreement is an empirical question. Thus the paper estimates the economic impacts of proposed ASEAN+3 trade agreements on the South Asian economy using Global Trade Analysis Project (GTAP) framework. The findings reveal that South Asia will be affected adversely in terms of GDP growth, export and also welfare-wise.

동해안 사질지반에 시설된 인공어초 3종의 매몰 특성

Using multi beam echo sounder, side scan sonar and scuba diving equipment, ceramic type, uneven type and semicircle-ramus type reefs into sandy bottom were ascertained, the depth of submersion in 7.2-10.3m on the coast of Gangneung, East of Korea, forty uneven type artificial reefs(AR) were totally buried into the sandy bottom. Two of five semicircle-ramus type ARs had only of their top area exposed. For most of the 45 ceramic reefs, only the upper 25-150cm of ARs were visible. The burial pattern is different in west and east side of the reefs, where the east side is deeply buried compared to the west side. From these results. it is recommended that sufficient analysis of bottom structure and materials especially in the sandy sea area should be undertaken in order to determine the best type of artificial reefs to be deployed and the best location for depoloyment.

동해 재분석 자료에 나타난 북한한류의 계절 및 경년변동성

Analyzing the results of East Sea Regional Ocean Model using a 3-dimensional variational data assimilation scheme, we investigated spatial and temporal variability of the North Korean Cold Current (NKCC) in the East Sea. The climatological monthly mean transport of the NKCC clearly shows seasonal variation of the NKCC within the range of about 0.35 Sv (<TEX>$=0^6m^3/s$</TEX>), which increases from its minimum (about 0.45 Sv) through December-January to March, decreases during March and May, and then increases again to the maximum (about 0.8 Sv) in August-September. The volume transport of the NKCC shows interannual variation of the NKCC with the range of about 1.0 Sv that is larger than seasonal variation. The southward current of the NKCC appears often not only in summer but in winter as well. The width of the NKCC is about 35 km near the Korean coast and its core is located under the East Korea Warm Current. The North Korean Cold Water (NKCW), characterized by low salinity and low temperature, is located both under the Tsushima Warm Water and in the western side of the maximum southward current of the NKCC that means the NKCC advects the NKCW southward along the Korean coast. It is revealed that the intermediate low salinity water, formed off the Vladivostok in winter, flows southward to the south of <TEX>$37^{\circ}N$</TEX> through <TEX>$2{\sim}3$</TEX> paths; one path along the Korean coast, another one along <TEX>$132^{\circ}E$</TEX>, and the middle path along <TEX>$130^{\circ}E$</TEX>. The path of the intermediate low salinity varies with years. The reanalysis fields suggest that the NKCW is advected through the paths along the Korean coast and along <TEX>$130^{\circ}E$</TEX>.

On the regional background levels of carbon monoxide observed in East Asia during 1991∼2004

The carbon monoxide (CO) concentrations observed in Mt. Waliguan in China (WLG), Ulaan Uul in Mongolia (UUM), Tae-ahn Peninsula in Korea (TAP) and Ryori in Japan (RYO) were analysed between 1991 and 2004. The average annual concentration of CO, a toxic air pollutant, was the highest at TAP (233 ± 41 ppb), followed by RYO (171 ± 36 ppb), UUM (155 ± 26 ppb) and WLG (135 ± 22 ppb). CO tends to be highest in spring and lowest in summer in East Asia, with the exception of WLG. TAP had the highest CO concentrations in all seasons compared with WLG, UUM and RYO and displays a wide short-term variability in concentration. This is caused by large-scale air pollution owing to its downwind location, close to continental East Asia. CO concentrations observed at TAP were analysed as follows: according to the origin of the isentropic backward trajectory and its transport passage, as continental background airflows (CBG) measuring 216 ± 47 ppb, regionally polluted continental airflows (RPC) measuring 316 ± 56 ppb, oceanic background airflows (OBG) measuring 108 ± 41 ppb and partly perturbed oceanic airflows measuring 161 ± 6 ppb. The high concentrations of CO at TAP are because of the airflow originating from the East Asian continent, rather than the North Pacific. RPCs, which pass through eastern China, appear to have high CO concentrations in spring, autumn and winter. OBGs, however, are affected by North Pacific air masses with low CO concentrations in summer. National Oceanic and Atmospheric Administration satellite images and the Goddard Earth Observing System (GEOS)-Chem simulation model confirmed that a large-scale air pollution event originated in eastern China and reached the Korean Peninsula and the Korea East Sea by way of the Yellow Sea. It is noteworthy that the overall trend at TAP does not show an increase despite the fact that energy use in China approximately doubled from 1991 to 2004.

Spatial and temporal variability of satellite-observed Subpolar Front in the East/Japan Sea

Spatial and temporal variability of the Subpolar Front (SPF) in the East/Japan Sea are examined based on semi-monthly sea-surface-temperature (SST) gradient maps constructed from declouded SST images over the period 1990–1995. Analyses demonstrate that the SPF experiences distinct seasonal fluctuations as well as strong year-to-year variations in terms of frontal strength, position, and zonal range. Elevated variability of the SPF is attributed mainly to mesoscale eddies at the frontal region. The main SPF is not zonal along 40 ∘ N but trends from the southwest to the northeast during winter–spring, and from the northwest to the southeast in summer. During summer, the SPF west of 135 ∘ E shifts significantly to the north, reaching 41 . 5 ∘ N , which is associated with an enhancement of the East Korea Warm Current (EKWC). However, the surface SPF does not necessarily reflect its subsurface structure. Because of strong baroclinicity in summer, the internal SPF surface is inclined to the south with increasing depth. Northward movement of the western SPF is limited to 20 m depth. Topography may give vorticity constraints on the migration of the SPF, but the maximum SPF is not always located around the shallow Yamato Rise (YR) in the central part of the East/Japan Sea. Relatively strong bathymetrically trapped fronts are confined to the northwestern edge of the YR, within a zonal range of 132.5 – 134 . 5 ∘ E , where steep bathymetry stabilizes the fronts. Topographic steering of SST fronts is weak at the southeastern portion of the YR. The SPF in the EKWC region ( < 132 ∘ E ) is not significantly affected by the bathymetry. Spatial variability of atmospheric wind forcing produces a significant meridional shift of the SPF by generating the northwestern branch of the SPF in November. The strongest frontal zone, of magnitude 0.09 ∘ C / km , near 138 ∘ E shows the largest temporal variability in strength, but the smallest temporal variability in terms of meridional location. A temporal trend of the SPF properties is observed, suggesting that its western (eastern) location migrates to the south (north) reaching - ( + ) 0 . 1 ∘ / year with mean strengthening of 6.8 × 10 - 4 ∘ C / km year during the study period.

East of Korea and West of Japan… The Very Model of Modern Major Oceanography

East of Korea and West of Japan… The Very Model of Modern Major Oceanography

강릉시 연안 문어어업에 관한 연구- II - 문어흘림낚시어업 -

A survey on the fishing gear for octopus drift-line fishing was done in Gangwon-do, Sacheon, Gyeongnam and Hokkaido, Japan, while a survey on the environments of fishing grounds used data from January to August from the Korea east coast farming forecast system of Donghae Fisheries Research and Development Institute. The present situation of fishing was examined with boats engaging in drift-line fishing from March to August in the coastal waters along Gangneung. The fishing tackle for octopus drift-line fishing was made manually, and the size, shape, and weight of the hook and number of shooting used vary according to the fishing time and region. Lead is used as the material for sinkers. As bait, pork fat with skin is mostly used in Gangwon-do. The temperature of the bottom water layer in the coastal fishing ground of Gangneung from April to June ranges from <TEX>$3.2-12.4^{\circ}C$</TEX>, which is the optimal temperature for octopuses. During July and August, the temperature ranges from <TEX>$5.0-20.6^{\circ}C$</TEX>. The maximum difference between day and night temperatures reached up to <TEX>$9.2^{\circ}C$</TEX>. Salinity is generally stable at <TEX>$33.2-35.324.6%_{\circ}$</TEX>, which does not affect the inhabitation of octopuses. The octopus catch reached its peak from May to July, while most octopuses weighed less than 1 kg (76.7%). The results show that it is effective to carry out octopus drift-line fishing up to a depth of 40 meters; and that the maximum number of octopuses per line is obtained with an operation time of six hours.

Synoptic forcing of the Korea Strait transport

Abstract Korea Strait transport variations in the synoptic frequency band (2–20 days) are examined using results of a numerical 3-D primitive equation model, satellite observed sea-level variations, a linear barotropic adjoint dynamic model, and observed transports. The 3-D numerical model does not assimilate observations, and the agreement with the observed transport implies that wind forcing is one of the main contributors to variations in the synoptic band. The satellite-observed and 3-D model sea-level indicate a sea-level response to wind stress along the east Korean coast that propagates toward the Korea Strait and changes the sea-level slope across the strait. The adjoint results indicate that wind stress is most influential in the area east of Korea along with secondarily important area along the East China Sea shelf break south of Japan. The mechanism connecting wind stress to transport variations is a Kelvin wave propagation that changes sea-level slope across the strait, leading to the altered geostrophic transport through the strait. A strong southerly wind initially produces a sea-level set down along the east Korea coast and a sea-level increase along the shelf break. The set down propagates to the Korea Strait as a Kelvin wave, sea level across the strait changes, and the transport through the strait increases. Similarly, northerly wind stress produces a set up along the Korea coast and subsequent decreased transport. Wind stresses across the Yellow and East China Seas are not a significant forcing mechanism since Kelvin waves would propagate away from the strait. Barotropic transport response to wind stress is rapid (on the order of 3 h), but the relatively slow development of the atmospheric forcing (on the order of 1–2 days) modulates the response.

Monthly Variation of Sea-Air Temperature Differences in the Korean Coast

Monthly variations of sensible heat, latent heat and momentum fluxes and the modi- fication of sea temperature to air temperature were examined at four coastal sta- tions—Sokcho, Kangnung, Ulsan and Chungmu in the path of the East Korea Warm Current from the year of 1981 to 1990, which was one of main migration routes of Japanese common squid. The difference between monthly averaged sea surface and air temperatures at the 10 m height above the sea surface mainly became negative values from April through August, while they had positive ones from September through March. Monthly variability of the temperature differences is significant in both summer and winter, while it is generally small in spring and fall. Negative val- ues of sensible heat fluxes, which indicated a heat gain by the sea through heat con- duction across the air-sea interface were found at the four coastal stations from April to August. Minimum values of sensible heat fluxes at Sokcho, Kangnung and Chungmu were in June, except for Ulsan in August. To the contrary, positive sensible heat flux implying a heat loss from sea toward atmosphere occurred from October to February with a maximum in December. Latent heat fluxes due to condensation of moist air over sea surface had small magnitudes from April to August and those due to evapo- ration of water particles from the sea surface into the lower atmosphere had rela- tively large magnitudes from October to March. Minimum values of latent heat fluxes also occurred in June except for August in Ulsan. Momentum flux was small from June to August under weak wind in summer, but it was large from December to Feb- ruary under strong wind in winter. Regression equations between sea surface tem- perature and air temperature at the 10 m height above the sea surface had very high correlation coefficients from 0.92~0.98, except for 0.78~0.84 of Ulsan, which was par- tially affected by upwelling of cool water from the bottom into the sea surface. Simi- lar to the sea surface, correlation coefficients were over 0.83~0.97 except for 0.70~0.79 for Ulsan at the 10 m depth of sea and were over 0.70~0.95 except for 0.59~0.82 for Ulsan at the 20 m depth.

OMP 방법으로 분석한 하계 동해의 수계 특성

하계 동해의 기원 해수 T-S diagram 방법에다 용존 산소를 추가시키고, 자료를 위도-경도 평면상에서 표시하는 방법으로 기원해수를 판별하였다. 하계에 동해에서 총 8개의 기원해수가 판별되었다. 표층해수로는 1) 고온-저염의 EKCW, 2) 고온-최저염의 NKSW, 3) 고온-고염의 MTSW, 4) 저온-저염의 TSCW의 4종류와 5) 최고염의 TMW, 6) 저온-저염-고농도의 산소를 가지는 LCW인 2종류의 중층수 그리고 심층수로 7) 저온-고염-고농도의 산소를 가지는 ESIW, 8) 최저온-고염-저농도의 산소를 가지는 ESPW 8종류로 구분할 수가 있었다. 특히, 동해 중 북부 해역에서 발견된 최저염의 NKSW(North Korea Surface Water), 기존에 알려진 대마난류 표층수에 비해 고염의 특징을 보여준 MTSW(Modified Tsushima Surface Water), 그리고 타타르 해협에서 시베리아 연안을 따라 남하하는 TSCW(Tatar Surface Cold Water)등이 이번 연구에서 새롭게 정의되었다. 조성비로 본 기원 해수의 흐름 총 8개의 기원해수에 대해 조성비 50% 이상을 기준으로 한 각 기원해수의 흐름을 Fig. 7에 나타내었다. 먼저 표층의 흐름을 보면, EKCW는 대한해협 서수도를 통해 동해 연안을 따라 북상하는 흐름을 보였고, MTSW는 대단해협 동수도를 통해 동해로 진입하여 <TEX>$40^{\circ}N$</TEX> 부근까지 영향을 미쳤다. TSCW는 타타르 해협에서 시베리아 연안을 따라서 블라디보스톡 부근까지 남하를 하였고, NKSW는 동해 중부의 <TEX>$40^{\circ}NP{\sim}42^{\circ}N$</TEX> 부근에 국지적으로 분포하였다(Fig. 7a). 중층에서는, TMW가 <TEX>$40^{\circ}N$</TEX> 부근까지 영향을 미쳤고, 동해 북부 해역에서 기원한 LCW와 ESIW에 세력에 막혀 더 북진을 못하고 동진하는 것으로 판단되었다. LCW는 동해 북부해역에서 반시계 방향의 순환하는 흐름과 연안을 따라서 남하하는 흐름 두 종류의 흐름이 있는 것으로 판단되었다(Fig. 7b). 심층에서는, ESIW가 동해 북부 연안을 따라 <TEX>$36^{\circ}N$</TEX> 부근까지 남하하는 흐름을 보였고, ESPW는 수심 500m 부근에서 시베리아 연안을 따라 남부 연안까지 남하하는 한 줄기가 있음을 알 수 있었다. 점차 수심이 깊어지면서 동해 남 북부 전체를 ESPW로 채우고 있어 어떤 흐름의 특징보다는 동해 전체의 상당한 부피를 차지함을 알 수 있었다(Fig. 7d). 동해 북부해역에서 생성되는 냉수들이 연안을 따라서 동해 남부해역으로 이동하는 흐름을 보여주었다. 따라서 동해 내부 순환의 큰 줄기는 연안을 따라 흐르는 냉수들의 흐름이며, 매년 동해남부 해역에 발생하는 용승 현상도 이러한 흐름의 연장선에 있음을 짐작할 수 있다(Lee and Kim 2003). CREAHS II carried out an intensive hydrographic survey covering almost entire East Sea in 1999. Hydrographic data from total 203 stations were released to public on the internee. This paper summarized the results of water mass analysis by OHP (Optimum Multiparameter) method that utilizes temperature, salinity, dissolved oxygen, pH, alkalinity, silicate, nitrate, phosphate and location data as an input data-matrix. A total of eight source water types are identified in the East Sea: four in surface waters(North Korea Surface Water, Tatar Surface Cold Water, East Korean Coastal Water, Modified Tsushima Surface Water), two intermediate water types (Tsushima Middle Water, Liman Cold Water), two deep water types (East Sea Intermediate Water, East Sea Proper Water). Of these NKSW, MTSW and TSCW are the newly reported as the source water type. Distribution of each water types reveals several few interesting hydrographic features. A few noteworthy are summarized as follows: The Tsushima Warm Current enter the East Sea as three branches; East Korea Coastal Water propagates north along the coast around <TEX>$38^{\circ}N$</TEX> then turns to northeastward to <TEX>$42^{\circ}N$</TEX> and moves eastward. Cold waters of northern origin move southward along the coast at the subsurface, which existence the existence of a circulation cell at the intermediate depth of the East Sea. The estimated volume of each water types inferred from the OMP results show that the deep waters (ESIW + ESPW) fill up ca. 90% of the East Sea basins. Consequently the formation and circulation of deep waters are the key factors controlling environmental condition of the East Sea.

SEA LEVEL VARIATIONS AND SEA SURFACE CIRCULATIONS IN THE KOREAN SEAS BY SATELLITE ALTIMETER DATA

Sea level variations and sea surface circulations in the Korean seas were observed by Topex/Poseidon altimeter data from 1993 through 1997. In sea level variations, the West and South Sea showed relatively high variations with comparison to the East Sea. Then, the northern and southern area in the West Sea showed the range of 20~30cm and 18~24cm, and the northern west of Jeju island and the southern west of Tsushima island in the South Sea showed the range of 15~20 cm and 10~15 cm, respectively. High variations in the West Sea was results to the inflow in sea surface of Yellow Sea Warm Current (YSWC) and bottom topography. Sea level variations in the South Sea was due to two branch currents (Jeju Warm Current and East Korea Warm Current) originated from Kuroshio Current (KC). In sea surface circulations, there existed remarkably three eddies circulations in the East Sea that are mainly connected with North Korea Cold Current (NKCC), East Korea Warm Current (EKWC) and Tushima Warm Current (TWC). Their eddies are caused basically to the influence of currents in sea surface circulations; Cyclone (0.03 cm/sec) in the Wonsan bay off shore with NKCC, and anticyclone (0.06 cm/sec) in the southwestern area of Ulleung island with EKWC, and cyclone (0.01 cm/sec) in the northeastern area of Tushima island with TWC, respectively

ON EAST ASIAN SAND AND DUSTSTORMS AND ASSOCIATED SIGNIFICANT DUSTFALL OBSERVED FROM JANUARY TO MAY 2001

Monitoring of dust pollution at the western shore of Tae-ahn Peninsula (TAP) and in the Chongju area of central Korea was carried out from January to May 2001. It was found that in Koreathere were 9 cases of sand and duststorms (DS) and 16 associatedsignificant dustfall (SD) days. Observed maximum concentrations of DS and SD coming from NW China and Mongolia were in the rangeof 300–920 for TSP, 200–690 for PM10 and 100–170 μg m-3 for PM2.5.Satellite measurements clearly showed the formation and subsequent movement of DS to the Korean Peninsula and onward to the Korea East Sea, Japan and the Gulf of Alaska. According to satellite image analysis of dust clouds there were abundant coarse particles, measuring in size of 11.0 μm. Medium-sizedparticles measuring in the range of 3.5–7.0 were also prevalent,while fine particles of less than 2.0 μm were less distinctive in reflectivity. Measured values of PM2.5 were alsorelatively low with SD events.The measured average pH values of dusty precipitation associatedwith DS were 7.24. Alkaline precipitation can play a `temporary'role in the neutralization of acidified soil until the subsequentevent of acidic rain. The new selection criteria of SD days from PM2.5 at 85 μg m-3, PM10 190 μg m-3 and TSP 250 μg m-3 are recommended on dust pollution occurring from the invasion of a DS elsewhere.