• Ocean and Polar Research
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• v.21 no.2
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• pp.127-136
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• 1999

Radiolarian assemblages from KODOS area were analyzed in order to understand the biostratigraphy and paleoceanography of deep-sea sediment from the Northeast Equatorial Pacific. The sediment core was divided into two or three units on the basis of the chemical and physical properties. In the upper sediment, mixtures of Quaternary and Tertiary radiolarians are found indicating active reworking processes. Dissolution of radiolarians seem to increase with depth. Radiolarians are seldom in Unit III presumably due to dissolution and corrosion. The middle part of unit I appears to correspond to Collosphaera invaginata Zone (0.21 Ma). Unit II belongs to Collosphaera tuberosa Zone. Based on the absence of Stylatractus universus, we estimate its age to be younger than 0.42 Ma. Based on our analyses of radiolarians in Unit I and II, we estimated the age of unit III as Tertiary, particularly from Oligocene to Miocene. There may to be hiatuses of more than 3 My from late Miocene to Pliocene, which probably resulted from erosion and dissolution by the Antarctic Bottom Water Sedimentation rates during Quaternary range from 0.15 to 0.50 mm/ky with significant variabilities among stations. Radiolarians in the study area were mostly warm-water species.

• Atmosphere
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• v.25 no.1
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• pp.179-183
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• 2015

Even though state-of-the-art general circulation models is improved step by step, the seasonal predictability of the East Asian summer monsoon still remains poor. In contrast, the seasonal predictability of western North Pacific and Indian monsoon region using dynamic models is relatively high. This study builds canonical correlation analysis model for seasonal prediction using wind fields over western North Pacific and Indian Ocean from the Global Seasonal Forecasting System version 5 (GloSea5), and then assesses the predictability of so-called hybrid model. In addition, we suggest improvement method for forecast skill by introducing the lagged ensemble technique.

• Ocean and Polar Research
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• v.26 no.2
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• pp.377-384
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• 2004

Annual variations of inorganic nutrients such as nitrate(+nitrite), phosphate and silicate in association with thermocline were investigated in the upper 200 m of the water column at KODES Long-term Monitoring (KOMO) station in the northeast equatorial Pacific from 1995 to 2002. Global climatic disturbances such as El Nino and La Nina, should have affected KODES area during the study period. In 1995-97 and 2000-2002, a thermocline where temperatures rapidly decrease with depth, was formed at 50-70 m water depth. Nutrient depletion, specially for nitrate and phosphate, was extended down to approximately 50 m depth, which coincided with the surface mixed layer depth. In 1998 and 1999, however a very fluctuating thermocline was observed at 20-100 m water depth. In the photic zone (up to 100 m depth), depth integration of nitrate, phosphate and silicate ranged from 2.02 to $23.14\;gN/m^2$, from 0.87 to $4.05\;gP/m^2$ and from 35.67 to $176.21\;gSi/m^2$, respectively. As a result of changes in the water column structures, nutrient concentrations also showed fluctuation parallel to the changes of thermocline in the study area.

• Ocean and Polar Research
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• v.26 no.2
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• pp.287-298
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• 2004

As a part of Korea Deep Ocean Study program, we investigated the distribution of planktonic protists in the upper 200 m of the northeast Pacific from $5^{\circ}N$ to $17^{\circ}N$, along $131^{\circ}30'W$. Area of divergence was formed at $9^{\circ}N$ which is boundaries of the north equatorial counter current (NECC) and the north equatorial current (NEC) during this cruise. Chlorophyll-a concentration was higher in NECC than in NEC area. Pico chl-a(<$2\;{\mu}m$) to total chl-a accounted for average 89% in the study area. The contribution of pico chl-a to total chl-a was relatively high in NEC area than in NECC area. Biomass of planktonic protists, ranging from 635.3 to $1077.3\;mgC\;m^{-2}$(average $810\;mgC\;m^{-2}$), was most enhanced in NECC area and showed distinct latitudinal variation. Biomass of HNF ranged from 88.7 to $208.3\;mgC\;m^{-2}$ and comprised 15% of planktonic protists. Biomass of ciliates ranged from 123.6 to $393.0\;mgC\;m^{-2}$ and comprised 25% of planktonic protists. Biomass of HDF ranged from 407.2 to $607.8\;mgC\;m^{-2}$ and comprised 60% of planktonic protists. HDF was the most dominant component in both NECC and NEC areas. Nano-protist biomass accounted for more than 50% of total protists in the both areas. The contribution of nanoprotist to total protists biomass was relatively higher in NEC area than in NECC. The biomass of planktonic protists was significantly correlated with phytoplankton biomass in this study area. The size structure of phytoplankton biomass coincided with that of planktonic protists. This suggested that the structure of the planktonic protists community and the microbial food web were dependent on the size structure of the phytoplankton biomass. However, biomass and size structure of planktonic protist communities might be significantly influenced by physical characteristics of the water column and food concentration in this study area.

• Ocean and Polar Research
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• v.36 no.4
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• pp.395-405
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• 2014

A 570 cm-long sediment core was retrieved at $9^{\circ}57^{\prime}N$ and $131^{\circ}42^{\prime}W$ in 5,080 m water depth from the northeast equatorial Pacific and its stratigraphy was established with $^{10}Be/^9Be$ and paleomagnetic measurements. Successive AF demagnetization reveals eight geomagnetic field reversals. In the reference geologic time scale, the eight reversal events correspond to an age of about 4.5 Ma. However, $^{10}Be/^9Be$-based age yields 9.5 Ma at a depth of 372 cm. Such a large discrepancy in determined ages is attributed to an extremely low sedimentation rate, 0.4 mm/kyr on average, of the study core and resultant loss or smoothing of geomagnetic fields. The composite age model reveals a wide range in the sedimentation rate - varying from 0.1 to 2.4 mm/kyr. However, the sedimentation rate shows systematic variation depending on sedimentary facies (Unit II and III), which suggests that each lithologic unit has a unique provenance and transport mechanism. At depths of 110-80 cm with a sedimentation rate of about 0.1 mm/kyr, ancient geomagnetic field reversal events of at least a 1.8 Myr time span have not been recorded, which indicates the probable existence of a hiatus in the interval. Such a sedimentary hiatus is observed widely in the deep-sea sediments of the NE equatorial Pacific.

• Ocean and Polar Research
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• v.26 no.2
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• pp.265-272
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• 2004

This study was conducted to investigate the community structure and distributional pattern of meiobenthos in the deep-sea bottom of the Clarion-Clipperton Fracture Zone of northeastern Pacific during July 2001. Examination of sediment samples collected on the eight survey station showed that there were 10 different types of meiobenthos. The most abundant meiobenthic animals were nematodes in all stations. Sarcomastigophorans, benthic harpacticoids were next abundant meiobenthos. Vertical distribution of meiobenthic animals showed the highest individual numbers in the surface sediment layers of 0-1 cm depth and showed more steep decreasing trend as sediment gets deeper on the stations of high latitude located in $16-17^{\circ}N$. Horizontal distribution of meiobenthic animal in the study area within CCFZ showed high densities of meiobenthos at the stations had few manganese nodules on their sediment surface in the site of low latitude. For size distribution analyses showed that animals which fit into the sieve mesh size of 0.063 mm were abundant.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.285-288
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• 2008

We analyzed evaporation data in the Japanese Ocean Flux Data Sets with Use of Remote Sensing Observations (J-OFURO) Ver.2. There exists huge evaporation in Gulf Stream, Kuroshio Extension, the ocean dessert and the southern part of the Indian Ocean. The temporal variation of evaporation is overwhelmingly large, of which the standard deviation is more than 120(mm), in the Kuroshio Extension region. Also, the result of harmonic analysis gives that this large variation is closely related to annual variation. In addition, the first EOF mode shows long-term variation showing the maximum amplitude between 1992 and 1994 and remarkable decrease after 1994, and large amplitude in the equatorial region and northeast of Australia. The second and third modes were strongly influenced by El Nino. Moreover, we compared J-OFURO2 evaporation product with other products. We used six kinds of data sets (HOAPS3 and GSSTF2 of satellite data, NRA1, NRA2, ERA40 and JRA25 of reanalysis data) for comparison. Most products show underestimation in the most regions, in particular, in the northern North Pacific, mid-latitudes of the eastern South Pacific, and high-latitudes of the South Pacific compared with J-OFUR02. On the other hand, JRA25 and NRA2 show large overestimation in the equatorial regions. RMS difference between NRA2 and J-OFURO2 in the Kuroshio Extension was significantly large, more than 120(mm).

• Journal of the military operations research society of Korea
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• v.17 no.1
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• pp.25-42
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• 1991

Participation of ROK navy in the Rim of the Pacific(RIMPAC) in likely to stimulate rethinking of Korea's defense role in Northeast Asia. Although the RIMPAC exercise was originally maneuvers to improve combat techniques in ASW, anti-aircraft combat. ocean supply support. surface combat. and electronics warfare. it will be finally be directed to ward securing the SLOC connecting the US, Canada. Australia and the Far East. Based on this concept, my conclusion is that two future arrangements are possible for the security of the Korean peninsula and protecting the SLOC in the combined defense of the Pacific. One is the naval cooperation between ROK and Japan. the other is the Standing Naval Force Pacific(STANAVFORPAC) The concepts of the Naval Cooperation between ROK and Japan and the STANAVFORPAC is whose time has come. The leaders, policymakers, and planners of the countries concerned need to consider such a move seriously.

• Korean Journal of Environmental Biology
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• v.35 no.1
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• pp.64-82
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• 2017

Two species of the minuta-subgroup within the oncaeid copepod genus Triconia $B{\ddot{o}}ttger$-Schnack, 1999 collected in the equatorial Pacific Ocean are newly recorded. A female T. minuta (Giesbrecht, 1893 ["1892"]) and both male and female T. umerus ($B{\ddot{o}}ttger$-Schnack and Boxshall, 1990) from the northeast equatorial Pacific are redescribed with the comparison of its morphological details, which differs from previous studies, in terms of the larger body size, the length to width ratio of the genital double-somite, the relative length of the outer basal seta on P5, and the ornamentation of the appendages. The characters, which are used for identification, such as the length ratio of the outer subdistal and outer spine versus the distal spine on P3-P4, and the outer spine length of the middle exopodal segment on P3 and P4 are reported for the first time. Information on the variations in the endopodal spine lengths of swimming legs 2-4 is also provided for T. minuta and T. umerus, with the summary of the wide zoogeographical distribution of these two species.

• Ocean and Polar Research
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• v.24 no.3
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• pp.197-205
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• 2002

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.