• Journal of the korean society of oceanography
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• v.31 no.4
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• pp.207-216
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• 1996

A geochemical study of three piston cores (ST.4, ST.6 and ST.20) taken from the Northwest Pacific (eastern edge of Shikoku Basin) provides information about changes in surface water paleoproductivity and sedimentation during the last 127 kys. Paleoproductivity variations were estimated on the basis of total organic carbon content and carbonate mass accumulation rate. The paleoproductivity based on total organic carbon shows significant spatial variations between glacial and interglacial periods. During the last glacial maximum (LGM) paleoproductivity increased about 1.5 times with deglaciation decrease compared with those of the Holocene at inner side of the Shikoku Basin (ST.4 and ST.6). On the other hand, paleoproductivity at outer side of Shikoku Basin (ST.20) indicating not distinctive increase but deglaciation increase. The C/N ratios fall below 10 for cores ST.4 and ST.6, but C/N ratios between 100 ka and 80 ka in ST.20 which show around 10 or larger values suggest a predominance of marine organic carbon with some admixture of terrigenous materials. The carbonate mass accumulation rate of three cores show different patterns of calcareous record with respect to organic carbon based paleoproductivity variation. In the inner side of Shikoku Basin (ST.4 and ST.6) the carbonate mass accumulation rate decreased during last glacial maximum, and significant increase of carbonate mass accumulation rate is recognized at outer side of Shikoku Basin (ST.20). Thus, this set of data reveals that spatial paleoproductivity variations between inner and outer side of Shikoku Basin during the glacial and interglacial periods.

• Ocean and Polar Research
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• v.33 no.3
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• pp.281-290
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• 2011

This study examined the change in sea surface temperature (SST) around the Korean peninsula since industrialization at year 1880, and its possible causes using observation based data from the Hadley Center, the Goddard Institute of Space Studies, and National Climate Data Center. Since year 1880, There have been multi-decadal fluctuations with a gradual reduction from 1880 to around 1940, and from 1950-1980. There has then been a marked increase from 1940-1950, and from 1980 to the present. The ocean surface warming is larger during the boreal winter than summer, and greater in the south. The multi-decadal SST fluctuations around the Korean Peninsula are largely consistent with the negative phase of the Pacific Decadal Oscillation (PDO), which fluctuates with periods of about 20-50 years. Secondly, the El Ni$\tilde{n}$o-Southern Oscillation (ENSO), whose long period component moves along with the PDO, appears to influence the SST near the Korean Peninsula, especially in recent decades. Overall, the SST around the Korean Peninsula has warmed since year 1880 by about $1^{\circ}C$, which is about twice the global-mean ocean surface warming. This long-term warming is aligned with an increase in greenhouse gas concentration, as well as local factors such as the PDO.

• Ocean and Polar Research
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• v.35 no.2
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• pp.85-92
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• 2013

The coral symbiotic algae zooxanthellae is often expelled from the host as the host coral is under physiological stress, causing the coral to turn completely white. Such coral bleaching events are occurring more frequently with the increase in the global warming, ocean acidification and increased level of anthropogenic impacts such as eutrophication. In the present study, we investigated the effects of inorganic nutrients including ammonium, nitrate, phosphate and elevated water temperature on the symbiotic zooxanthellae density in the fragment of branching coral Acropora nobilis. Zooxanthellae density in the host coral decreased 8 hrs after the experiment at a given elevated water temperature ($32^{\circ}C$, p < 0.05). In contrast, no clear coral bleaching or decrease in the symbiotic algae density was observed from the branching coral exposed to a normal water temperature of $30^{\circ}C$ and high levels of nutrients such as 20 ${\mu}M$ of $NH_4Cl$, 20 ${\mu}M$ of $NaNO_3$ and, 10 ${\mu}M$ $KH_2PO_4$. Accordingly, the data indicated high water temperature is one of the stressful factors to cause bleaching in A. nobilis, whereas the high levels of nutrients is not a factor. It is believed that the results obtained in the present study are useful as baseline information in the management of the coral reefs.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.3
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• pp.135-141
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• 2001

A paleomagnetic investigation was carried out to analyze magnetostratigraphic information and to evaluate the relationship between paleoenvironment and magnetic properties in sedimentary sequences of piston cores recovered from the abyssal basin of the southwestern Pacific. Pateomagnetic results revealed that the sediments had a stable remanent magnetization and recorded both normal and reversal polarities. The age of sediments was from late Pliocene and Pleistocene determined by matching the polarities with the geomagnetic time scale. The sedimentation rates were in the range of 0.63-1.85 mm/$10^3$ year which were extremely low rates. The results of the paleomagnetic analyses indicated that intervals of the magnetically stable layers as well as high value of susceptibility were significantly affected by the input changes which resulted input of large-quantity materials of relatively stable magnetic carriers.

• Korean Journal of Remote Sensing
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• v.37 no.3
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• pp.615-625
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• 2021

The coastal areas around Palau Island and Tonga Island, near the Pacific equator, consist of coral reefs, mangrove and seaweed. In particular, understanding the optical properties of sea surface water in coral reef habitats helps improve the accuracy of remote sensing based habitat mapping and identify tropical ecosystem characteristics. Here, we collected spectral characteristics of sea surface water of Palau Island and Tonga Island and analyzed the concentration of suspended matters, absorption coefficient, and remote sensing reflectance to understand the seawater characteristics of the coral reef habitats. Based on the results of the suspended matter concentration analysis, we developed and verified an empirical algorithm to derive the concentration from satellite data using remote sensing reflectance of three bands, 555, 625, 660 nm, showed a high determinant coefficient, 0.98. In conclusion, coral reef habitats in tropical regions are characterized by CASE-I water in terms of the marine optics with oligotrophic properties, and require monitoring using continuous collection and analysis of field data.

• Journal of the Korean earth science society
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• v.27 no.6
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• pp.687-694
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• 2006

This paper investigated the effects of wind stress forcing in the western North Pacific on ENSO decadal change before and after the late 1970s. The SVD analysis of SODA data shows that a positive wind stress curl is dominant in the western North Pacific at the ENSO mature phase, which leads to the ENSO phase change by discharge/recharge heat contents in the equatorial Pacific. Before the late 1970s, the wind stress curl in the western North Pacific was strong. This strong wind forcing that is associated with the fast discharge of heat contents in the equator led to the short period and the weak intensity of ENSO occurred during the 1960-1970. On the other hand, after the late 1970s the relatively weak wind stress curl was accompanied with the long period and the strong intensity of ENSO. The simple coupled model experiments also confirm that the amplitude and dominant period of ENSO decrease when the wind stress curl in the western North Pacific projects more strongly into the ocean at the TNSO mature phase. Our results support that the changes in the behavior of ENSO after the late 1970s are associated with the wind stress variation in the western North Pacific.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1995.10a
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• pp.13-15
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• 1995

The horizontal and vertical circulations are considered in the South China Sea, based on the 80 years' winds (COADS), 10 years' XBTs (NODC), and about 10 years' sea-level data at Kaoshiung, Taiwan and Singapore. The South China is largest marginal sea in the western North Pacific, which is predominantly governed by Southeast Asian Monsoons. (omitted)

• 한국수산학회:학술대회논문집
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• 2005.05a
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• pp.209-210
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• 2005

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.04a
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• pp.125-126
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• 2002

Fishman et al.(1987)의 연구를 시작으로 인공위성 자료를 이용하여 적도지역의 대류권 오존에 대한 연구가 활발해졌다. 적도지역의 대류권 오존의 분포는 Atlantic Ocean에서 최대값을 가지며 Pacific Ocean에서 최소값을 가지는 wave pattern을 보인다. S. America와 S. Africa에서 연중 dry season(6-9월)에 biomass burning로 인해 대류권 오존의 최대값이 나타난다. 인공위성 자료를 이용한 대류권 오존을 구하는 방법은 다음과 같다. (중략)

• Proceedings of the KSRS Conference
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• 1999.11a
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• pp.231-236
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• 1999

Accurate ocean surface fluxes with high resolution are critical for understanding a mechanism of global climate. However, it is difficult to derive those fluxes by using ocean observation data because the number of ocean observation data is extremely small and the distribution is inhomogeneous. On the other hand. satellite data are characterized by the high density, the high resolution and the homogeneity. Therefore, it can be considered that we obtain accurate ocean surface by using satellite data. Recently we constructed ocean surface data sets mainly using satellite data. The data set is named by Japanese Ocean Flux data sets with Use of Remote sensing Observations (J-OFURO). Here, we introduce J-OFURO. The data set includes shortwave radiation, longwave radiation, latent heat flux, sensible heat flux, and momentum flux etc. Moreover, sea surface dynamic topography data are included in the data set. Radiation data sets covers western Pacific and eastern Indian Ocean because we use a Japanese geostationally satellite (GMS) to estimate radiation fluxes. On the other hand, turbulent heat fluxes are globally estimated. The constructed data sets are used and shows the effectiveness for many scientific studies.