• Title/Summary/Keyword: Antarctic sea

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Stratigraphy and Paleoceanography of deep-sea core sediments from the Korea Deep Ocean Study (KODOS)-97 Area, Northeast Equatorial Pacific (북동태평양 KODOS-97지역 주상 퇴적물의 층서 및 고해양학적 연구)

  • Park, Jeong-Hee;Kim, Ki-Hyune
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.4 no.1
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    • pp.50-62
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    • 1999
  • Sediment core samples recovered from the Korea Deep Ocean Study (KODOS)-97 area were divided into two or three units according to their distinct changes in sediment colors and chemical and physical properties. Analyses of radiolarian faunas in the sediments and $^{10}Be$ ratios in each unit were performed to reveal stratigraphic and paleoceanographic history of the study area. In the upper part of the sediments, Tertiary radiolarians were mixed at various proportions with Quaternary assemblages probably by reworking process of bottom current and benthic animals. Dissolution of radiolarians was severe in deeper depth and in the Unit III, only few of the fragments of corroded Tertiary radiolarians were detectable. The mid layer of the Unit I belonged to Collosphaera invaginata Zone, the time period of 0.21 Ma. The Unit II belonged to Collosphaera tuberosa Zone with the time period younger than 0.42 Ma which was observed above the Stylatractus universus Zone. The Unit III is assigned to Tertiary, which is younger than the Late Eocene. Composition analyses of radiolarian assemblage and $^{10}Be$ ratio data indicated hiatus periods of more than 3 My between late of Middle Miocene and Pliocene resulting from erosion and dissolution caused by Antarctic Bottom Water. Stratigraphic evidence from radiolaria was well correlated with $^{10}Be$ data. Sedimentation rate during Quaternary can be suggested as 0.15-0.5 mm per 1000 years. Dominance of warm-water radiolaria species and the results reflected minimum climatic changes of tropical conditions.

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Spatial Distribution of Extremely Low Sea-Surface Temperature in the Global Ocean and Analysis of Data Visualization in Earth Science Textbooks (전구 대양의 극저 해수면온도 공간 분포와 지구과학교과서 데이터 시각화 분석)

  • Park, Kyung-Ae;Son, Yu-Mi
    • Journal of the Korean earth science society
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    • v.41 no.6
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    • pp.599-616
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    • 2020
  • Sea-surface temperature (SST) is one of the most important oceanic variables for understanding air-sea interactions, heat flux variations, and oceanic circulation in the global ocean. Extremely low SSTs from 0℃ down to -2℃ should be more important than other normal temperatures because of their notable roles in inducing and regulating global climate and environmental changes. To understand the temporal and spatial variability of such extremely low SSTs in the global ocean, the long-term SST climatology was calculated using the daily SST database of satellites observed for the period from 1982 to 2018. In addition, the locations of regions with extremely low surface temperatures of less than 0℃ and monthly variations of isothermal lines of 0℃ were investigated using World Ocean Atlas (WOA) climatology based on in-situ oceanic measurements. As a result, extremely low temperatures occupied considerable areas in polar regions such as the Arctic Ocean and Antarctic Ocean, and marginal seas at high latitudes. Six earth science textbooks were analyzed to investigate how these extremely low temperatures were visualized. In most textbooks, illustrations of SSTs began not from extremely low temperatures below 0℃ but from a relatively high temperature of 0℃ or higher, which prevented students from understanding of concepts and roles of the low SSTs. As data visualization is one of the key elements of data literacy, illustrations of the textbooks should be improved to ensure that SST data are adequately visualized in the textbooks. This study emphasized that oceanic literacy and data literacy could be cultivated and strengthened simultaneously through visualizations of oceanic big data by using satellite SST data and oceanic in-situ measurements.

Analysis of Development Characteristics of the Terra Nova Bay Polynya in East Antarctica by Using SAR and Optical Images (SAR와 광학 영상을 이용한 동남극 Terra Nova Bay 폴리냐의 발달 특성 분석)

  • Kim, Jinyeong;Kim, Sanghee;Han, Hyangsun
    • Korean Journal of Remote Sensing
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    • v.38 no.6_1
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    • pp.1245-1255
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    • 2022
  • Terra Nova Bay polynya (TNBP) is a representative coastal polynya in East Antarctica, which is formed by strong katabatic winds. As the TNBP is one of the major sea ice factory in East Antarctica and has a great impact on regional ocean circulation and surrounding marine ecosystem, it is very important to analyze its area change and development characteristics. In this study, we detected the TNBP from synthetic aperture radar (SAR) and optical images obtained from April 2007 to April 2022 by visually analyzing the stripes caused by the Langmuir circulation effect and the boundary between the polynya and surrounding sea ice. Then, we analyzed the area change and development characteristics of the TNBP. The TNBP occurred frequently but in a small size during the Antarctic winter (April-July) when strong katabatic winds blow, whereas it developed in a large size in March and November when sea ice thickness is thin. The 12-hour mean wind speed before the satellite observations showed a correlation coefficient of 0.577 with the TNBP area. This represents that wind has a significant effect on the formation of TNBP, and that other environmental factors might also affect its development process. The direction of TNBP expansion was predominantly determined by the wind direction and was partially influenced by the local ocean current. The results of this study suggest that the influences of environmental factors related to wind, sea ice, ocean, and atmosphere should be analyzed in combination to identify the development characteristics of TNBP.

Tectonics of the south Shetland Islands and Geology of king George Island: A Review (남쉐틀랜드군도의 지체구조 및 킹죠지섬의 지질)

  • 이민성;박병권
    • 한국해양학회지
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    • v.25 no.2
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    • pp.74-83
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    • 1990
  • The similarity in Mesozoic geology between the Antarctic Peninsula and South America indicates the possibility that they had situated along the same tectonics line before the separation of southwestern Gondwanaland. The igneous activity around the Antarctic Peninsula, including the South Shetland islands, can be correlated with the South American Cordillera Orogeny due to the subduction of Farallon/Phoenix plate until late Mesozoic. However igneous activity in Tertiary correlates with the tectonics movement accompanying the formations of Drake passage and Scotian sea. The south Shetland islands form a Jurassic-Quaternary miasmatic island arc on the sialic basement of schist and deformed sedimentary rocks. Forming of the South Shetland Islands arc began during the latest Jurassic or earliest Cretaceous from the southwestern part of the archipelago. The igneous activity migrated northeasterly and continued in most areas until late Tertiary. The entire arc-forming period, between late Jurassic and late tertiary times, was characterized by emplacement and eruption of magmas of intermediate between island-arc tholeiite and calc-alkaline types. However, Quaternary volcanic rocks show strong alkaline affinities which corresponds to the switch from compressional to intra: plate tensional tectonics. The rocks of late Cretaceous to Tertiary, mainly found in King George Island, consist of lava of basalt to andesite and intercalated pyroclastic rocks. Some of the volcanic rocks, which ofter called quartz-pyrite lodes'are severely altered and include much content of calcite,silica and pyrite.The stratographic succession of King George Island can be divided into two formation:Fields formation and Hennequin formation.The Fildes formation crops out at the west side of Admiralty Bay n King George Island,while the Hennequin formation at the east side of the bay.These two formtions are thought to be formed contempiranceously.The Fildes formation consists of altered olivine-basalt and basaltic andestie, whereas the Hennequin formation consists of fine-grained hypersthene-augite-andesite.Both formations interclate pyroclastic rocks.

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The Characteristics of Physical Oceanographic Environments and Bottom Currents in the KODOS Study Area of the Northeastern Tropical Pacific (동태평양 KODOS 탐사해역에서의 물리해양환경 및 저층해류 특성)

  • Shin, Hong-Ryeol;Hwang, Sang-Chul;Jeon, Dong-Chull;Kim, Ki-Hyune;Kwak, Chong-Heum;So, Seun-Seup
    • Ocean and Polar Research
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    • v.26 no.2
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    • pp.341-349
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    • 2004
  • Hyrdography and deep currents were measured from 1997 to 1999 to investigate deep-sea environments in the KODOS (Korea Deep Ocean Study) area of the northeastern tropical Pacific. KODOS area is located meridionally from the North Equatorial Current to the boundary between the North Equatorial Current and the Equatorial Counter Current. Strong thermocline exists between 10 m and 120 m depths at the study area. Since that strong thermocline does hardly allow vertical mixing between surface and lower layer waters, vertical distributions of temperature, salinity, dissolved oxygen and nutrients drastically change near the thermocline. Salinity-minimum layer, which indicate the North Pacific Intermediate Water (NPIW) and the Antartic Intermediate Water (AAIW), vertically occupies vertically at the depths from 500 m down to 1400 m. The NPIW and the AAIW horizontally occur to the north and to the south of $7^{\circ}N$, respectively. The near-bottom water shows the physical characteristics of $1.05^{\circ}C$ and 34.70 psu at the depths of 10 m to 110 m above the bottom (approximately 4000-5000 m), which was originated from the Antarctic Circumpolar Water. It flows northeastwards for 2 to 4 months at the study area, and its mean velocity was 3.1-3.7 cm/s. Meanwhile, reverse (southwestward) currents appear for about 15 days with the average of 1.0-6.1 cm/s every 1 to 6 months. Dominant direction of the bottom currents obtained from the data for more than 6 months is northeastward with the average speeds of 1.7-2.1 cm/s. Therefore, it seems that deep waters from the Antarctica flow northwards passing through the KODOS area in the northeastern tropical Pacific.

Analysis of Ice Velocity Variations of Nansen Ice Shelf, East Antarctica, from 2000 to 2017 Using Landsat Multispectral Image Matching (Landsat 다중분광 영상정합을 이용한 동남극 난센 빙붕의 2000-2017년 흐름속도 변화 분석)

  • Han, Hyangsun;Lee, Choon-Ki
    • Korean Journal of Remote Sensing
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    • v.34 no.6_2
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    • pp.1165-1178
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    • 2018
  • Collapse of an Antarctic ice shelf and its flow velocity changes has the potential to reduce the restraining stress to the seaward flow of the Antarctic Ice Sheet, which can cause sea level rising. In this study, variations in ice velocity from 2000 to 2017 for the Nansen Ice Shelf in East Antarctica that experienced a large-scale collapse in April 2016 were analyzed using Landsat-7 Enhanced Thematic Mapper Plus (ETM+) and Landsat-8 Operational Land Imager (OLI) images. To extract ice velocity, image matching based on orientation correlation was applied to the image pairs of blue, green, red, near-infrared, panchromatic, and the first principal component image of the Landsat multispectral data, from which the results were combined. The Landsat multispectral image matching produced reliable ice velocities for at least 14% wider area on the Nansen Ice Shelf than for the case of using single band (i.e., panchromatic) image matching. The ice velocities derived from the Landsat multispectral image matching have the error of $2.1m\;a^{-1}$ compared to the in situ Global Positioning System (GPS) observation data. The region adjacent to the Drygalski Ice Tongue showed the fastest increase in ice velocity between 2000 and 2017. The ice velocity along the central flow line of the Nansen Ice Shelf was stable before 2010 (${\sim}228m\;a^{-1}$). In 2011-2012, when a rift began to develop near the ice front, the ice flow was accelerated (${\sim}255m\;a^{-1}$) but the velocity was only about 11% faster than 2010. Since 2014, the massive rift had been fully developed, and the ice velocity of the upper region of the rift slightly decreased (${\sim}225m\;a^{-1}$) and stabilized. This means that the development of the rift and the resulting collapse of the ice front had little effect on the ice velocity of the Nansen Ice Shelf.

Foreign Entry Strategies for Korean Fishery Firms (한국수산업의 해외진출전략에 관한 연구)

  • 김회천
    • The Journal of Fisheries Business Administration
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    • v.15 no.1
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    • pp.131-153
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    • 1984
  • Fishery resources are still abundant compared with other resources and the possibility of exploitation is probably great. The Korean fishery industry has grown remarkably since 1957, and Korea is ranked as one of the major fishery countries. Its of fishery products reached the 9th in the world and the value of exports was 5th in 1982. But recently a growth rate has slowed down, due to the enlargement of territorial seas by the declaration of the 200 mile, Exclusive Economic Zone, the tendency to develop fishery resources strate-gically in international bargaining, the change in function of the international organizations, the expansion of regulated waters, the illegal arrest of our fishing boats, the rapid rise in oil prices, and the fall in fish prices, the development of fishery resources as a symbol of nationalism, the fishing boats decreptitude, the rise of crew wages, regulations on fishing methods, fish species, fishing season, size of fish, and mesh size, fishing quotas and the demand of excessive fishing royalties. Besides the the obligation of coastal countries, employing crews of their host countries is also an example of the change in the international environment which causes the aggravation of foreign profit of fishing firms. To ameliorate the situation, our Korean fishery firms must prepare efficient plans and study systematically to internationalize themselves because such existing methods as conventional fishing entry and licence fishing entry are likely to be unable to cope with international environmental change. Thus, after the systematic analysis of the problem, some new combined alternatives might be proposed. These are some of the new schemes to support this plan showing the orientation of our national policy: 1. Most of the coastal states, to cope with rapid international environmental change and to survive in the new era of ocean order, have rationalized their higher governmental structure concerning the fishery industries. And the coastal countries which are the objectives of our expecting entry, demand excessive economic and technical aid, limit the number of fishing boats’entry and the use of our foreign fishing bases, and regulate the membership of the international fishery commissions. Especially, most of the coastal or island countries are recently independent states, which are poorer in national budget, depend largely on fishing royalties and licence entry fees as their main resources of national finance. 2. Alternatives to our entry to deep sea fishing, as internationalization strategies, are by direct foreign investment method. About 30 firms have already invested approximately US $ 8 million in 9 coastal countries. Areas of investment comprise the southern part of the Atlantic Ocean, the Moroccan sea and five other sea areas. Trawling, tuna purse seining and five other fields are covered by the investment. Joint-venture is the most prominent method of this direct investment. If we consider the number of entry firms, the host countries, the number of seas available and the size of investment, this method of cooperation is perhaps insufficient so far. Our fishery firms suffer from a weakness in international competitive ability, an insufficiency of information, of short funds, incompetency in the market, the unfriendliness of host coastal countries, the incapability of partners in joint-ventures and the political instability of the host countries. To enlarge our foreign fishing grounds, we are to actively adopt the direct investment entry method and to diversity our collaboraboration with partner countries. Consequently, besides proper fishing, we might utilize forward integration strategies, including the processing fied. a. The enterprise emigration method is likely to be successful in Argentina. It includes the development of Argentinian fishing grounds which are still not exploited in spite of abundant resources. Besides, Arentina could also be developed as a base for the exploitation of the krill resources and for further entries into collaboration with other Latin American countries. b. The co-business contract fishing method works in American territorial seas where American fishermen sell their fishery products to our factory ships at sea. This method contributes greatly to obtaining more fishing quotas and in innovation bottom fishing operation. Therefore we may apply this method to other countres to diffuse our foreign fishing entry. c. The new fishing ground development method was begun in 1957 by tuna long-line experimental fishing in the Indian Ocean. It has five fields, trawling, skipjack pole fishing and shrimp trawling, and so on. Recently, Korean fisheries were successful in the development of the Antarctic Ocean krill and tuna purse seining. 3. The acceleration of the internationalization of deep sea fishing; a. Intense information exchange activities and commission participation are likely to be continues as our contributions to the international fishery organizations. We should try to enter international fishery commissions in which we are not so far participating. And we have to reform adequately to meet the changes of the function of the international commissions. With our partner countries, we ought to conclude bilateral fishery agreements, thus enlarging our collaboration. b. Our government should offer economic and technical aids to host countries to facilitate our firms’fishery entry and activities. c. To accelerate technical innovation, our fishery firms must invest greater amount in technical innovation, at the same time be more discriminatory in importing exogeneous fishery technologies. As for fishing methods; expanded use of multi-purpose fishing boats and introduction of automation should be encuraged to prevent seasonal fluctuations in fishery outputs. d. The government should increases financial and tax aid to Korean firms in order to elevate already weak financial structure of Korean fishery firms. e. Finally, the government ought to revise foreign exchange regulations being applied to deep sea fishery firms. Furthermore, dutes levied on foreign purchaed equipments and supplies used by our deep sea fishing boats thould be reduced or exempted. when the fish caught by Korean partner of joint-venture firms is sold at the home port, pusan, import duty should be exempted.

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Data Reductions of Gravity Recovery and Climate Experiment (GRACE) Gravity Solutions and Their Applications (Gravity Recovery and Climate Experiment (GRACE) 중력자료 해석을 위한 자료 처리 및 응용)

  • Seo, Ki-Weon
    • Journal of the Korean earth science society
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    • v.32 no.6
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    • pp.586-594
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    • 2011
  • Gravity Recovery and Climate Experiment (GRACE), launched in April, 2002, makes it possible to monitor Earth's mass redistribution with its time-varying gravity observation. GRACE provides monthly gravity solutions as coefficients of spherical harmonics, and thus ones need to convert the gravity spectrum to gravity grids (or mass grids) via the spherical harmonics. GRACE gravity solutions, however, include spatial alias error as well as noise, which requires to suppress in order to enhance signal to noise ratio. In this study, we present the GRACE data processing procedures and introduce some applications of time-varying gravity, which are studies of terrestrial water storage changes, Antarctic and Greenland ice melting, and sea level rise. Satellite missions such as GRACE will continue up to early 2020, and they are expected to be an essential resource to understand the global climate changes.

Nest Distribution of Skuas on Barton and Weaver Peninsulas of the King George Island, the Antarctic (남극 킹조지 섬의 바톤 및 위버 반도에서 번식하는 도둑갈매기류의 둥지 분포)

  • Kim, Jeong-Hoon;Chung, Ho-Sung;Kim, Ji-Hee;Yoo, Jeong-Chil;Ahn, In-Young
    • Ocean and Polar Research
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    • v.27 no.4
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    • pp.443-450
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    • 2005
  • The ratio of breeding pairs of brown skuas (Catharacta lonnbergi), south polar skuas (C. maccormicki) and mixed species pairs between Barton and Weaver peninsulas remained the same $(X^2-test,\;X^2=0,503,\;df=2,\;p=0.778)$. The nests of skuas were clustered on Barton, whereas they were distributed randomly on the Weaver peninsula. The distance between brown skua nests, and that of mixed species pair nests were longer than those of south polar skua nests. Brown skua nests were distributed along the coast. Whereas, the nests of mixed species pairs and south polar skuas were found more frequently inland (Kruskal-Wallis, $X^2=11.631$, df=2, p<0.005). There was no interspecific difference in the distances between skua nests and Penguin rookery at Barton (Kruskal-Wallis, $X^2=2.153$, df=2, p=0.341) or at King Sejong Station (ANOVA, F=1.483, df=2, p=0.229). In general, skuas prefer lower locales (<125m above sea level) for their nest building sites. Brown skua nests were distributed mainly on the beach, whereas south polar skua were distributed on the predominant periglacial landforms and till areas $(X^2-test,\;X^2=24.988,\;df=8,\;p<0.005)$.

Isolation and Identification of the Crude Oil-degrading Psychrotrophic Bacterium and the Characteristics of OCT Plasmid (저온성 원유분해 세균의 분리동정 및 OCT 프라스미드 특성)

  • 김상진;윤희정
    • Microbiology and Biotechnology Letters
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    • v.21 no.1
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    • pp.66-73
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    • 1993
  • Psychrotrophic bacterial strains utilizing crude oil as their sole carbon and energy sources were isolated from Antarctic soil and sea sediments. One of the strains named AI-I showed the hightest activity for emulsification of crude oil and the best growth. This strain was identified as Acinetobacter calcoaceticus. A. calcoaceticus AI-I strain contains a plasmid (OCT plasmid) which was related to the utilization of alkane compounds. The molecular weight of this plasmid was estimated to be about 110 Md by agarose gel electrophoresis. The cured strain of A. calcoaceticus AI-I strain (OCT ) was not able to utilize normal hydrocarbon compounds ($C_6C_{17}$) as carbon and energy sources. A. ca/coaceticus AI-1 was resistant to ampicillin and sensitive to streptomycin, kanamycin, chloramphenicol, tetracycline. The results suggested that this strain carries a plasmid (OCT) responsible for oil utilization which is quite stable and might be concerned with antibiotics resistancy.

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