• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.4
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• pp.259-264
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• 2001

Typhoon and neap tide on Cochlodinium polykrikoides bloom and water temperature on disappearance of C. polykrikoides bloom were investigated to elucidate the outbreak mechanism of C. polykrikoides blooms at Naro and Namhae coastal area in South Sea of Korea. The first observation of C. polykrikoides blooms were observed when thermocline was disappeared by typhoon, tide, etc. The first blooms of C. polykrikoides were observed on neap tide or before one day from neap tide in 1996-1998 and 2000. However, thermocline was disappeared by typhoon in 1994 and 1999, the first blooms were observed early 12-30 day than 1996-1998 and 2000. The main reason of disappearance of C. polykrikoides blooms after typhoon on 1997-2000 seems to be other environmental change by typhoon rather than low water temperature. In the future, the first C. polykrikoides bloom will be appear around the first neap tide of latter part of August with breaking down of thermocline, but if the thermocline be collapsed by typhoon in July, the C. polykrikoides bloom will be appear at beginning of August. The outbreak of C. polykrikoides blooms will be explain as follows: The vegetative cells, which was germinated by environmental change or already exist in surface water at low level, input to the surface water, and then nutrients and trace metals which were suppled from out side of C. polykrikoides bloom area inflow to surface. The vegetative cells are growth by the nutrients and trace metals at suitable environmental conditions e.g. water temperature, salinity, and sufficient light.

• Journal of the Geological Society of Korea
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• v.54 no.5
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• pp.489-499
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• 2018

A series of geological events such as the formation of the Antarctic continental ice sheets, the changes in ocean circulation and a mass extinction after the onset of Oligocene has been studied as major concerns by various researches. However, paleoclimatic and paleoceanographic changes during the most period of Oligocene since the Eocene-Oligocene transition (EOT) still remains unclear. Especially, although the late Oligocene warming (LOW) has been assessed as the largest period in the paleoceanographic changes, the detailed understanding on the changed components is very low. The purpose of this study is the reconstruction of the paleoceanographic history during the late Oligocene using core sediments from IODP Expedition 342 Site U1406 performed in J-Anomaly Ridge in North Atlantic. Because North Atlantic deep water (NADW) has flowed southward through the study area since the early Oligocene, this area has been considered to an important location for studies on the changes of NADW. The core sediment analyzed in this study were deposited from about 26.0 to 26.5 Ma as evidenced by both of onboard and shore-based paleomagnetic data, and this is corresponded to the earliest period of LOW. The sediment profile can be divided into three Units (Unit 1, 2 & 3) based on the changes in both of total number and test size of Oridorsalis umbonatus as well as grain size data of clastic sediments. Unit 2 represents largest values in these three data. Because the total number, test size of O. umbonatus and grain size can be proxy records on the oxygen concentration and circulation intensity of deep water, we interpreted that Unit 2 had been deposited during the period of relatively strengthened NADW. Previous Cibicidoides spp. stable isotope results from the low latitude region of the North Atlantic also support our interpretation that is the intensified formation of NADW during the identical period. In conclusion, our results present a new evidence for the previous ideas that the causes on LOW are directly related to the changes in NADW.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.3
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• pp.190-199
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• 2008

To investigate hydrographic structure and characteristics of the tropical ocean in the eastern and the western Pacific, CTD(Conductivity-Temperature-Depth) data along $131^{\circ}W$ and $137^{\circ}-142^{\circ}E$ in July-August 2005 were analyzed. Sea surface temperature along $131.5^{\circ}W$ in summer is highest in the Equatorial Counter Current(ECC) because of the high-temperature water greater than $28^{\circ}C$ moving through the ECC from the western Pacific to the eastern Pacific in spring and summer. Based on the evidence of the presence of low salinity and high dissolved oxygen water in the North Equatorial Current(NEC), we suggested that the low salinity water moved from the Gulf of Panama to the east of Philippine along the North Equatorial Current(NEC). The South Equatorial Current(SEC) had the most saline water from surface to deep layer because the saline water from the Subtropical South Pacific Ocean moved to the north. The salinity minimum layer was observed at 500-1500 m depth along $131.5^{\circ}W$. The water mass with the salinity minimum layer in the north of $5^{\circ}N$ came from the North Pacific Intermediate Water(NPIW) and that in the south of $5^{\circ}N$ came from the Antarctic Intermediate Water(AAIW), which was more saline than the NPIW. Cyclonic cold eddy with a diameter of about 200km was found in $4-6^{\circ}N$. Sea surface temperature along $131.5^{\circ}W$ in the eastern Pacific was lower than along $137^{\circ}-142^{\circ}E$ in the western Pacific; on the other hand, sea surface salinity in the eastern Pacific was higher than in the western Pacific. Subsurface saline water from the Subtropical South Pacific Ocean was less saline in the eastern Pacific than in the western Pacific. Salinity and density(${\sigma}_{\theta}$) of the salinity minimum layer south of $14^{\circ}N$ was higher in the eastern Pacific than in the western Pacific.