Intermediate Water Formation at the Japan/East Sea Subpolar Front

Dissolved oxygen (DO) is one of the most important oceanographic parameters measured for understanding various physicochemical processes in the ocean. This situation has been particularly true for the East Sea study ever since the first extensive investigation in the area during the 1930s (<xref ref-type="bibr" rid="bib23">Uda, 1934</xref>). Uda found very high and uniform concentrations of DO, around 250 µM (5.6 ml/l), for waters below a few hundred meters over entire basins, and assumed that a very fast ventilation system was operating in the East Sea. The Circulation Research of the East Asian Marginal Seas (CREAMS), Japan-Korea-Russia international cooperative studies on the East Sea have provided a unique opportunity to investigate the entire East Sea for the first time since Uda’s study. A spectrophotometrically modified Winkler method (<xref ref-type="bibr" rid="bib16">Pai et al., 1993</xref>) and a DO sensor (Sea Bird Model SBE 13) were tested successfully during the CREAMS studies for improving the precision and accuracy of DO measurement. The study further confirmed an earlier observation by <xref ref-type="bibr" rid="bib7">Gamo et al. (1986)</xref> that DO structures in the East Sea have been changing drastically in such a way that the DO minimum depths have deepened by more than 1000 meters during the last 30 years. While the causes for these changes are not known at the present time, the analysis of DO profiles strongly suggests that the mode of deep water ventilation system in the East Sea has shifted from bottom water formation in the past to intermediate water formation at the present time (<xref ref-type="bibr" rid="bib8">Kim and Kim, 1996</xref>). Studies of precise and accurate DO monitoring, along with other chemical tracers, deserve the highest priority for future research in the East Sea.

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Decadal Changes in Meridional Overturning Circulation in the East Sea (Sea of Japan)

Journal of Physical Oceanography ◽

10.1175/jpo-d-19-0248.1 ◽

2020 ◽

Vol 50 (6) ◽

pp. 1773-1791 ◽

Cited By ~ 1

Author(s):

MyeongHee Han ◽

Yang-Ki Cho ◽

Hyoun-Woo Kang ◽

SungHyun Nam

Keyword(s):

Sea Of Japan ◽

Bottom Water ◽

Meridional Overturning Circulation ◽

East Sea ◽

Intermediate Water ◽

Decadal Change ◽

Marginal Seas ◽

Water Formation ◽

Meridional Overturning ◽

Bottom Water Formation

AbstractMeridional overturning circulation (MOC) is vital to distributing heat, freshwater, and dissolved matter in semienclosed deep marginal seas such as the East Sea (ES) (Sea of Japan). As our understanding of the ES MOC remains incomplete, we attempted to fill this research gap. We analyzed the ES MOC and its decadal change (1993–2012), employing Hybrid Coordinate Ocean Model (HYCOM) global reanalysis. We found that the ES MOC, consisting of two counterrotating overturning cells in the late 1990s, changed into a single full-depth cell in the 2000s and reverted to two cells in the 2010s. The decadal change relates to weakening of the southward western boundary current at the intermediate layer and northward eastern boundary currents at the deep abyssal layer. We propose that surface warming and salinification favored reduced intermediate water formation and enhanced bottom water formation in the northwestern ES in the 2000s and were, therefore, key to the decadal change. Conditions unfavorable to intermediate water formation and favorable to bottom water formation in the winters of the 2000s, compared with the late 1990s, enhanced northward (westward) Ekman transport in the southern (northeastern) ES, successive advection of surface warm, saline water into water formation areas, and air–sea heat and freshwater exchanges linked to the January Arctic Oscillation. Our results indicated that the ES MOC is sensitive to both external atmospheric forcing and internal ES processes, which have implications for significant changes in the response of other marginal seas and global oceans to future climate variability.

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Occurrence and Evolution of Mesoscale Thermodynamic Phenomena in the Northern Part of the East Sea (Japan Sea) Derived from Satellite Altimeter Data

Remote Sensing ◽

10.3390/rs13061071 ◽

2021 ◽

Vol 13 (6) ◽

pp. 1071

Author(s):

Taekyun Kim ◽

Hyeong-Jun Jo ◽

Jae-Hong Moon

Keyword(s):

Japan Sea ◽

Reanalysis Data ◽

East Sea ◽

Spatiotemporal Variability ◽

Altimeter Data ◽

Intermediate Water ◽

Dipole Structure ◽

Northwestern Region ◽

New Perspective ◽

Monsoon Winds

Based on satellite measurements and oceanic reanalysis data, it has been possible to investigate the spatiotemporal variability of the mesoscale phenomena in the northern part of the East Sea (NES) where direct observations of currents and hydrographical conditions are scarce. For the first time, this study identifies the detailed spatiotemporal structure of the mesoscale features in the NES and the mechanism of its occurrence and evolution, which have important consequences on the distribution of the intermediate water masses in the East Sea. Here, we show that mesoscale thermodynamic phenomena in the northwestern region of the East Sea are characterized by a dipole structure associated with positive and negative sea surface height anomalies. These result in a strong thermal gradient between the seasonally non-persistent anomalies, which emerge and strengthen during late fall and early winter. In contrast to the previous finding of the relationship between winter monsoon winds and mesoscale features in the NES, we found that this relationship is crucial only to the emergence of the mesoscale phenomena. Consequently, we present a new perspective on the evolution mechanism of the mesoscale features in the NES. Of direct significance to the present study, thermohaline transport into the northwestern region of the East Sea regulates the strengthening and weakening of mesoscale features in the NES. Wind forcing may contribute to the emergence of the mesoscale features in the NES and then the intensification of the mesoscale activities is attributed to the intrusion of warm and fresh surface water advected from the southern part of the East Sea.

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A high-resolution three-dimensional numerical study of intermediate water formation in the Levantine Sea

Journal of Geophysical Research Atmospheres ◽

10.1029/98jc01196 ◽

1998 ◽

Vol 103 (C9) ◽

pp. 18497-18511 ◽

Cited By ~ 55

Author(s):

A. Lascaratos ◽

K. Nittis

Keyword(s):

High Resolution ◽

Numerical Study ◽

Three Dimensional ◽

Intermediate Water ◽

Levantine Sea ◽

Water Formation

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Cold Intermediate Water Formation in the Black Sea. Analysis on Numerical Model Simulations

Sensitivity to Change: Black Sea, Baltic Sea and North Sea ◽

10.1007/978-94-011-5758-2_29 ◽

1997 ◽

pp. 375-393 ◽

Cited By ~ 11

Author(s):

J. V. Staneva ◽

E. V. Stanev

Keyword(s):

Numerical Model ◽

Black Sea ◽

The Black Sea ◽

Intermediate Water ◽

Model Simulations ◽

Water Formation

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On the Intermediate Water in the Southwestern East Sea (Sea of Japan)

Oceanography of Asian Marginal Seas - Elsevier Oceanography Series ◽

10.1016/s0422-9894(08)70091-6 ◽

1991 ◽

pp. 129-141 ◽

Cited By ~ 4

Author(s):

C.H. Kim ◽

H.-J. Lie ◽

K.S. Chu

Keyword(s):

Sea Of Japan ◽

East Sea ◽

Intermediate Water

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Modeling a 200-Yr Interruption of the Holocene Sapropel S1

Quaternary Research ◽

10.1006/qres.1999.2100 ◽

2000 ◽

Vol 53 (1) ◽

pp. 98-104 ◽

Cited By ~ 58

Author(s):

Paul G. Myers ◽

Eelco J. Rohling

Keyword(s):

General Circulation Model ◽

General Circulation ◽

Deep Convection ◽

Circulation Model ◽

Intermediate Water ◽

Gulf Of Lions ◽

The Holocene ◽

Circulation Mode ◽

Oceanic General Circulation Model ◽

Water Formation

AbstractAn oceanic general circulation model, previously used to simulate the conditions associated with the Holocene Sapropel S1, is used to simulate the effects of a climate deterioration (represented as a cooling event) on the sapropelic circulation mode. The enhanced cooling (2°–3°C) induces deep convection in the Adriatic and the Gulf of Lions and intermediate water formation in the Aegean, where in all cases there had previously been only stagnant unventilated waters. The depths of ventilation (to ∼1250 m) are in agreement with core data from this period. The short decadal timescales involved in modifying the sapropelic circulation suggest that such a climatic deterioration may be associated with the interruption of S1 between 7100 and 6900 14C yr B.P., which divided the sapropel into two subunits.

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