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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Ocean and Polar Research
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Korea Institute of Ocean Science & Technology
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Volume & Issues
Volume 24, Issue 4 - Dec 2002
Volume 24, Issue 3 - Sep 2002
Volume 24, Issue 2 - Jun 2002
Volume 24, Issue 1 - Mar 2002
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Bathymetry and Marine Geophysical Observations of the Ayu Trough, Southern Philippine Sea: Implications for Crustal Extension and Structure
Jung, Mee-Sook ; Lee, Sang-Mook ;
Ocean and Polar Research, volume 24, issue 3, 2002, Pages 179~187
DOI : 10.4217/OPR.2002.24.3.179
The Ayu Trough, located in the southern end of the Philippine Sea, represents a divergent boundary between the Philippine Sea and the Caroline Plates. A detailed geophysical survey was carried out in the Ayu Trough by R/V Onnuri. Topographically, the Ayu Trough resembles an slow spreading ridge. The trough can be divided into three sections: the south
, and north
. The seafloor in the middle section is characterized by features asymmetric with respect to the axis. These features were probably produced by NW-SE and NNW-SSE extensions and seem to support the argument that the opening of the Ayu Trough occurred in an oblique fashion. Farther south, a long transform fault but with a short offset defines the boundary between middle and southern sections. The axial depth increases a stepwise to the south of
. A clear difference can be seen between the southern and middle sections with the latter exhibiting much higher mantle Bouguer anomaly values in the axial region. The anomaly indicates that the axial crust perhaps experienced a much higher degree of extension in the middle than in the southern section. The analyses of magnetic field data reveal that the region beyond 100km exhibits considerable variations, whereas the magnetic anomalies within 100km from the trough axis are very much subdued. This observation suggests that the opening of the Ayu Trough involved an initial stage of rifting of existing volcanic arcs, followed by production of new seafloor.
Reflection Seismology in the Southern Ayu Trough, a Slow-spreading Divergent Boundary
Hong, Jong-Kuk ; Lee, Sang-Mook ;
Ocean and Polar Research, volume 24, issue 3, 2002, Pages 189~196
DOI : 10.4217/OPR.2002.24.3.189
A multichannel seismic survey was conducted in the southern Ayu Trough which is the only spreading boundary between the Philippine Sea and Caroline plates. The seismic system used in this study comprises of 2.46-l sleeve gun and a 12-channel streamer with a group interval of 6.25m. Migration technique was used to analyze seismic velocity, and poststack depth migration was applied to the stacked data. The sediment thickness obtained from the depth section tends to increase with distance from the spreading axis. Sedimentation rates are poorly constrainted in the study area. The apparent half-spreading rates estimated from the sediment thickness and sedimentation rate from DSDP hole on the caroline plate are 4.7mm/yr and 7.9mm/yr at
, respectively, which are fester than Previously suggested. On the basis of new oblique spreading geometry, the recalculated spreading rates are 5.4mm/yr and 9.1mm/yr at
, respectively. Seismic sections show that the topography is asymmetric across the Ayu Trough and the acoustic basement is rough. These features are consistent with the earlier suggestion that the Ayu Trough is a slow-spreading divergent boundary. A detailed examination of seismic profiles away from the axis shows that sediments can be divided into two layers which implies a possible change in the spreading rate anuor sedimentation condition during the formation of the trough.
Total Field Magnetic Analysis of Nine Seamounts Northwest of the Marshall Islands, Western Pacific
Lee, Tae-Gook ; Lee, Sang-Mook ; Moon, Jae-Woon ; Lee, Kie-Hwa ;
Ocean and Polar Research, volume 24, issue 3, 2002, Pages 197~205
DOI : 10.4217/OPR.2002.24.3.197
Total magnetic field and high-resolution bathymetric data were collected over nine seamounts to the northwest of the Marshall Islands in the western Pacific. Magnetic parameters including inclination and declination were calculated from the magnetic anomalies using inversion algorithm of Plouff (1976), and a corresponding paleomagnetic pole was determined with the magnetic parameters. The paleomagnetic poles determined in this study were compared with the previous apparent polar wander path (APWP) of Pacific plate. Most seamounts of the study area have normal polarity. The study reveals that all nine seamounts in the study area formed in the southern hemisphere during the Cretaceous based on their comparison with the APWP of Pacific plate. The ages estimated from paleomagnetic poles can be divided by age into three groups: the oldest (OSM1 and OSM3), middle age (OSM2, OSM4, and 6-2), and the youngest (OSM5-1, 5-2, 5-3, and 6-1). The fermer two groups and the latter seem to be coincident with two distinct pulses of Cretaceous volcanic activity (115-90 Ma and 83-65 Ma). As a whole the seamounts at southwest of the study area are older than at those northeast.
Thermosalinograph Measurements in the Western Pacific Ocean in May and June, 2001
Lee, Jae-Hak ; Chung, Byoung-Chul ; Hwang, Keun-Choon ; Jeon, Dong-Chull ; Hwang, Sang-Chul ; Lee, Ha-Woong ;
Ocean and Polar Research, volume 24, issue 3, 2002, Pages 207~213
DOI : 10.4217/OPR.2002.24.3.207
We have analyzed sea surface temperature and salinity data collected in the western Pacific Ocean by using an automated Thermosalinograph (TSG) installed on the RV Onnuri during May - June of 2001. The TSG data exhibit characteristics of water masses distributed in the near surface layer of the cruise area very well. Especially, they reveal the diurnal surface temperature cycle and the effect of rainfall on temperature and salinity in the equatorial region, showing the effectiveness of the use of TSG. Problems to be improved for the better TSG operation are the method of water sampling and calibration of TSG sensors. Installation of a pressure gauge in the TSG system and periodical sensor calibration are strongly recommended to ensure reliability of data.
TEM Observations of Chemosynthetic Bacteria in the Deep-sea Hydrothermal Vents and Seep Organisms
Kim, Dong-Sung ; Ohta, Suguru ;
Ocean and Polar Research, volume 24, issue 3, 2002, Pages 215~223
DOI : 10.4217/OPR.2002.24.3.215
Symbiosis of chemoautrophic bacteria with the members of hydrothermal vent and cold seep communities in the deep-sea were examined by histology using transmission electron microscopy; Bathymodiolus spp. from Sagami Bay, the Iheya Ridge and the North Fiji Basin; and Ifremeria nautilei from the North Fiji Basin. Two species of Bathymodiolus, each from Sagami Bay and the Iheya Ridge harbored methane-oxidizing symbionts within their gill tissues. Vent gastropod Ifremeria nautilei from the hydrothermal vents of the North Fiji Basin housed two types of symbionts; one sulfur-oxidizing type and the other methane-oxidizing type. The occurrence of chemosynthetic symbionts in these organisms were expected before-hand based on the ecological observations of their habit. The other members of these groups from world oceans and the recent advances in the symbiosis of the vent and seep communities were reviewed.
Different Climate Regimes Over the Coastal Regions of the Eastern Antarctic Ice Sheet
Cunde, Xiao ; Dahe, Qin ; Zhongqin, Li ; Jiawen, Ren ; Allison, Ian ;
Ocean and Polar Research, volume 24, issue 3, 2002, Pages 227~236
DOI : 10.4217/OPR.2002.24.3.227
For ten firn cores, from both the eastern and the western side of Lambert Glacier basin (LGB), snow accumulation rate and isotopic temperature were measured far the recent 50 years. Results show that snow accumulation for five cores over the eastern side of LGB (GC30, GD03, GD15, DT001, and DT085) at Wilks Land and Princess Elizabeth Land increases, whereas it decreases at the western side (Core E, DML05, W200, LGB 16, and MGA) at Dronning Maud Land, Mizuho Plateau and Kamp Land. For the past decades, the increasing rate was
at the eastern side and the decreasing rate was
at the western side. Temperatures at the eastern LGB were also increased with the rate of
. At the western LGB it was difficult to see clear trends, which were confirmed by Instrumental temperature records at coastal stations. Although statistic analysis and modeling results display that both surface temperature and accumulation rate has increased trends in Antarctic ice sheet during 1950-2000, the regional distributions were much more different for different geographic areas. We believe that ice-core records at Wilks Land and Princess Elizabeth Land reflect the real variations of SST and moisture change in the southern India Ocean. For the Kamp Land and Dronning Maud Land, however circulation pattern was different, by which the climate was more complicated. The International Trans-Antarctic Scientific Expedition (ITASE) aimed to reveal an overall spatial pattern of climate change over Antarctic ice sheet for the past 200 years. This study points the importance of continental to regional circulation to annual-decadal scale climate change in Antarctica.
All Sky Camera and Fabry-Perot Interferometer Observations in the Northern Polar Cap
Wu Qian ; Killeen Timothy L. ; Solomon Stanley C. ; McEwen Donald J. ; Guo, Weiji ;
Ocean and Polar Research, volume 24, issue 3, 2002, Pages 237~247
DOI : 10.4217/OPR.2002.24.3.237
We report all sky camera and Fabry-Perot interferometer (FPI) observations of mesospheric gravity waves and a 12-hour wave at Resolute
and a joint observation of 10-hour wave with Eureka
. All sky camera observations showed a low occurrence of mesosphere gravity waves during equinoxes, which is similar to the mid-latitude region. A slightly higher occurrence near solstice appears to indicate that gravity waves are not filtered out by the neutral wind in the winter. The FPI observation of a 12-hour wave showed amplitude variations from day to day. The phase of the wave is mostly stable and consistent with the GSWM prediction in the winter. The phase shifts with season as predicted by the GSWM. Four events of the 12-hour wave were found in spring with amplitudes larger than the GSW predictions. The FPls at Resolute and Eureka also observed a wave with period close to 10 hours. The 10-hour wave maybe the result of the non-linear interaction between the semi-diurnal tide and the quasi-two day wave. Further studies are under way. Overall, the combined Resolute and Eureka observation have revealed some new fractures about the mesospheric gravity wave, tidal wave, and other oscillations.
Crustal Uplift and Microseismic Activity around Syowa Station, Antarctica
Kaminuma, Katsutada ;
Ocean and Polar Research, volume 24, issue 3, 2002, Pages 249~253
DOI : 10.4217/OPR.2002.24.3.249
There is a great deal evidence concerning crustal uplift, after deglaciation, in the vicinity of Syowa Station
from tide gauge data, seismic evidence, raised beaches, marine terraces, etc. The geomorphological and tide gauge data show that the crustal uplift is going on around Syowa Station. Seismic observations at Syowa Station started in 1959. Phase readings of the earthquakes have been published by National Institute of Polar Research once a year since 1968, as one of the Data Report Series. Eighteen local earthquakes were detected on short period seismograms at Syowa Station in 1990-2000. The seismicity during the period from 1990 to 2000 was lower than that from 1987 to 1989 when epicenters of local earthquakes were determined by tripartite seismic array. Local earthquake activity corroborates the crustal uplif4 which is an intermittent phenomenon. Sea level falling of 4.5 mm/y was found using data in 1975-1992. This felling rate is consistent with the geomorphological data. A route for repeat leveling survey was established in East Ongul Island. No appreciable change of sea level was observed for the last 14 years. A dynamics of the crustal uplift around Syowa Station has been discussed using geomorphological data, ocean tide, and seismic and leveling data, which is estimated to be an intermittent phenomenon. When local seismic activity is high, the crustal uplift is estimated to be going on. On the contrary, the crustal uplift is in dormancy when the local seismicity is low. Repeated leveling measurements suggest no significant changes, which further supports the idea that the crustal uplift in offshore is not a tilt trend movement but a block movement.
Distribution of Antarctic Sea Ice from Satellite Altimetry in the Weddell Sea: Preliminary Results
Kim, Jeong-Woo ; Hong, Sung-Min ; Hwang, Jong-Sun ; Yoon, Ho-Il ; Lee, Bang-Yong ; Kim, Yea-Dong ;
Ocean and Polar Research, volume 24, issue 3, 2002, Pages 255~261
DOI : 10.4217/OPR.2002.24.3.255
We investigated the distribution of sea ice using Topex/Poseidon (T/P) and ERS-1 .ada. altimeter data in the northwest Weddell Sea, Antarctica, between the area
. Using the Geo_Bad_1 flag of the Merged GDR of the T/P, we classified the surface into ocean, land, and sea. Total 257 cycles of altimeter measurements between Oct. 1992 and Sep. 1999 (for nearly 2570 days) were used to analyze the distribution of the Antarctic sea ice. We then calculated the surface area of ice coverage using SUTM20 map projection to monitor the periodic variations. Each year, the maximum and minimum coverage of the sea ice were found in late August and February in the study area, respectively. We also studied the sea ice distribution using ERS-1 altimeter data between
to compare with the T/P Using the Valid/Invalid flag of the Ocean Product, we analyzed the sea ice distribution between March and August of 1995, which showed very good coherence with the T/P measurements. Our preliminary results showed that the altimeter measurements can be effectively used to monitor the distribution of the sea ice in the polar region. However, the size of radar footprint, typically 2-6km depending on the roughness of the sea surface, may be too big to monitor the sharp boundary between ice and water/land. If more other altimeter mission data with dense coverage such as Geosat GM are analyzed together, this limitation can be significantly improved. If we also combine other microwave remote sensing data such as radiometer, and SSM/I, the result will be significantly enhanced.
Search for Gravity Waves with n New All-sky Camera System
Kim, Yong-Ha ; Chung, Jong-Kyun ; Won, Yong-In ; Lee, Bang-Yong ;
Ocean and Polar Research, volume 24, issue 3, 2002, Pages 263~266
DOI : 10.4217/OPR.2002.24.3.263
Gravity waves have been searched for with a new all-sky camera system over Korean Peninsular. The all-sky camera consists of a 37mm/F4.5 Mamiya fisheye lens with a 180 dog field of view, interference filters and a 1024 by 1024 CCD camera. The all-sky camera has been tested near Daejeon city, and moved to Mt. Bohyun where the largest astronomical telescope is operated in Korea. A clear wave pattern was successfully detected in OH filter images over Mt. Bohyun on July 18, 2001, indicating that small scale coherent gravity waves perturbed OH airglow near the mesopause. Other wave features are since then observed with Na 589.8nm and OI 630.0nm filters. Since a Japanese all-sky camera network has already detected traveling ionospheric disturbances (TID) over the northeast-southwest range of Japanese islands, we hope our all-sky camera extends the coverage of the TID's observations to the west direction. We plan to operate our all-sky camera all year around to study seasonal variation of wave activities over the mid-latitude upper atmosphere.
Surface Air Temperature Variations around the Antarctic Peninsula: Comparison of the West and East Sides of the Peninsula
Lee, Bang-Yong ; Kwon, Tae-Yong ; Lee, Jeong-Soon ; Won, Young-In ;
Ocean and Polar Research, volume 24, issue 3, 2002, Pages 267~278
DOI : 10.4217/OPR.2002.24.3.267
This study investigated the spatial characteristics of warming trends and the dipole-like pattern of temperature field in the Antarctic Peninsula using surface air temperature (SAT) of 10 stations in the vicinity of the Antarctic Peninsula. SAT data for the 1962-2001 period at 6 stations (Rothera, Faraday/Vernadsky, Bellingshausen, Orcadas, Esperanza, Halley) revealed in general the larger warming trends in autumn and winter except for Halley. The largest warming was shown for August in the west side of the Peninsula (more than
). On the other hand, the recent 14-year SAT data showed the strong warming trends at 9 stations except for Halley in the earlier period (April-June) than August for the 1962-2001 period. The largest warming appeared in May at Esperanza and Butler Island. SAT of the two sides showed significant positive correlations over most of the period except for the mid- and the late 1970s, in which significant negative correlations were found. In the correlation analysis between SAT and sea surface temperature (SST) anomalies in the NINO 3.4 region, strong negative correlation was found in the west side of the Peninsula. Details of the correlation analysis exhibited that the negative correlation was significantly strong from the early 1980s to the mid-1990s. However, it was difficult to find significant correlations of ENSO with SAT in the east side of the Peninsula. So, in this study it failed to find out clearly the out-of-phase relationship of SAT across the Antarctic Peninsula.
Natural and Anthropogenic Heavy Metal Deposition to the Snow in King George Island, Antarctic Peninsula
Hong, Sung-Min ; Lluberas, Albert ; Lee, Gang-Woong ; Park, Jun-Kun ;
Ocean and Polar Research, volume 24, issue 3, 2002, Pages 279~287
DOI : 10.4217/OPR.2002.24.3.279
Successive 24 snow samples, collected from a 1.2m snow pit at a site on the summit of Main Dome in King George Island, Antarctic Peninsula, were measured for heavy metals such as Pb, Cd, Cu, and Zn and other chemical species. The mean concentrations of heavy metals are 3.48pg/g for Pb, 0.10pg/g for Cd, 16.6 pg/g for Cu and 15.8 pg/g for Zn, respectively. Pb and Cd concentrations observed in our samples are very comparable to those reported for recent snow at other Antarctic sites, while Zn and Cu levels are much higher than those at other sites. The annual fallout fluxes of all heavy metals approximately calculated are, however, much greater in King George Island than at other sites. With respect to the estimates of natural contributions, sea salt spray is found to be a major contributor to Cd and Zn inputs to the snow and minor to Cu inputs. On the other hand, the anthropogenic input can account for a large part of Pb concentrations. A tentative estimate represents that local emissions could be responsible for more than half of the excess Pb flux to the snow in King George Island.
The Lago Sofia Conglomerate : Debris Flow to Hyperconcentrated Flow Deposits in a Cretaceous Submarine Channel, Southern Chile
Choe, Moon-Young ; Sohn, Young-Kwan ; Jo, Hyung-Rae ; Kim, Yea-Dong ;
Ocean and Polar Research, volume 24, issue 3, 2002, Pages 289~300
DOI : 10.4217/OPR.2002.24.3.289
The Lago Sofia conglomerates encased in the Cretaceous Cerro Toro Formation, southern Chile, represent a gigantic submarine channel system developed along a foredeep trough. The channel system consists of several tributaries along the trough margin and a trunk channel along the trough axis. Voluminous debris flows were generated ubiquitously along the tract of the submarine channel mainly by the failure of nearby channel banks or slopes. The flows transformed immediately into multiphase flows and resulted in very thick-bedded mass-flow deposits with a peculiar structure sequence. The mass-flow deposits commonly overlie fluted or grooved surfaces and consist of a lower division of clast-supported and imbricated pebble-cobble conglomerate with common basal inverse grading, and an upper division of clast- to matrix-supported and disorganized pebble conglomerate or pebbly mudstone with abundant intraformational clasts. The structure sequence suggests a temporal succession of a turbidity current, a bipartite hyperconcentrapted flow with active clast collisions near the flow base, and a cohesive debris flow probably with a rigid plug. The multiphase flow is interpreted to have resulted from transformation of clast-rich but cohesive debris flows. Cohesive debris flows appear to transform more easily into dilute flow types in subaqueous environments because they are apt to hydroplane. This is in contrast to the flow transitions in subaerial environments where noncohesive debris flows are dominant and difficult to hydroplane.
Origins and Paleoceanographic Significance of Layered Diatom Ooze from Bransfield Strait in the Northern Antarctic Peninsula around 2.5 kyrs BP
Yoon, Ho-Il ; Kim, Yea-Dong ; Park, Byong-Kwon ; Kang, Cheon-Yun ; Bae, Sung-Ho ; Yoo, Kyu-Chul ;
Ocean and Polar Research, volume 24, issue 3, 2002, Pages 301~311
DOI : 10.4217/OPR.2002.24.3.301
We used diatom and porewater data of two piston cores from the central subbasin and one from the western subbasin in the Bransfield Strait in the northern Antarctic Peninsula to elucidate the depositional mechanism of the layered diatom ooze. The layered diatom ooze is characterized by an abundance of organic carbon, biogenic silica, sulfde sulfur, and lower porewater sulfate concentration. This lack of pore-water sulfate concentration in the diatom ooze interval may reflect development of reducing micro-environment in which bacterially mediated sulfate reduction occurred. The negative relationship between the total organic carbon and sulfate contents, however, indicates that sulfate reduction was partly taking place but does not control organic carbon preservation in this unit. Rather, well-preserved Chaetoceros resting spores in the layered diatom ooze indicate a rapid sedimentation of the diatom as a result of repetitive iceedge blooms on the Bransfield shelf during the cold period (around 2500 yrs BP) when the permanent seaice existed on the shelf, During this period, it is expected that the downslope-flowing cold and dense water was also formed on the Bransfield shelf as a result of sea ice formation, playing an important role for the formation of layered diatom ooze in the Bransfield subbasins.
A Note on Magnetic Properties of Volcanic Rocks Collected from King George Island, Antarctic Peninsula
Funaki, Minoru ; Ogishima, Tomoko ;
Ocean and Polar Research, volume 24, issue 3, 2002, Pages 313~318
DOI : 10.4217/OPR.2002.24.3.313
The basic magnetic properties are reported for Eocene andesite and granitic andesite collected from the King Sejong Station and Marsh Runway at King George Island, South Shetland Islands Antarctic Peninsula. Samples A (andesite), B (granitic andesite) and D (granitic andesite) carry stable component of natural remanent magnetization (NRM), but sample C (andesite) unstable URM. These NRM stabilities are consistent with the domain structures estimated by the ratios of
values. On the basis of their Curie temperature, we infer magnetite as the main magnetic carrier for samples A B and C and titanomagnetite for sample D. Our study reveals that samples A and B are suitable for paleomagnetic investigations, whereas sample D is not.