Seasonal variations in the low-salinity intermediate water in the region south of sub-polar front of the East Sea (Sea of Japan)

Abstract. An ocean buoy, UBIM (Ulleung Basin Integrated Mooring), deployed during the spring transition from February to May 2010 reveals for the first time highly resolved temporal variation of biochemical properties of the upper layer of the Ulleung Basin in the southwestern East Sea/Sea of Japan. The time-series measurement captured the onset of subsurface spring bloom at 30 m, and collocated temperature and current data gives an insight into a mechanism that triggers the onset of the spring bloom not documented so far. Low-frequency modulation of the mixed layer depth ranging from 10 m to 53 m during the entire mooring period is mainly determined by shoaling and deepening of isothermal depths depending on the placement of UBIM on the cold or warm side of the frontal jet. The occurrence of the spring bloom at 30 m is concomitant with the appearance of colder East Sea Intermediate Water at buoy UBIM, which results in subsurface cooling and shoaling of isotherms to the shallower depth levels during the bloom period than those that occurred during the pre-bloom period. Isolines of temperature-based NO3 are also shown to be uplifted during the bloom period. It is suggested that the springtime spreading of the East Sea Intermediate Water is one of the important factors that triggers the subsurface spring bloom below the mixed layer.

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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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Descriptive Physical Oceanography of the North Pacific, Sea of Japan (East Sea) and Sea of Okhotsk.

10.21236/ada311009 ◽

1995 ◽

Author(s):

Janice D. Boyd

Keyword(s):

Sea Of Japan ◽

North Pacific ◽

Sea Of Okhotsk ◽

East Sea ◽

Physical Oceanography ◽

The North ◽

The North Pacific

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Trace element and helium isotope geochemistry of the Cenozoic intraplate volcanism in the East Sea (Sea of Japan): Implications for lithosphere-asthenosphere interaction

Lithos ◽

10.1016/j.lithos.2021.106075 ◽

2021 ◽

Vol 388-389 ◽

pp. 106075

Author(s):

Wonhee Lee ◽

Hyunwoo Lee ◽

Donghwan Kim ◽

Jonguk Kim ◽

Jihye Oh ◽

...

Keyword(s):

Trace Element ◽

Sea Of Japan ◽

Isotope Geochemistry ◽

East Sea ◽

Helium Isotope ◽

Intraplate Volcanism

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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 Climatology of Rossby Wave Breaking on the Southern Hemisphere Tropopause

Journal of the Atmospheric Sciences ◽

10.1175/2010jas3460.1 ◽

2011 ◽

Vol 68 (4) ◽

pp. 798-811 ◽

Cited By ~ 24

Author(s):

Thando Ndarana ◽

Darryn W. Waugh

Keyword(s):

Southern Hemisphere ◽

Rossby Wave ◽

Potential Vorticity ◽

Seasonal Variations ◽

Wave Breaking ◽

Polar Front ◽

Rossby Wave Breaking ◽

South Pacific Ocean ◽

Ocean Region ◽

Summer Minimum

Abstract A 30-yr climatology of Rossby wave breaking (RWB) on the Southern Hemisphere (SH) tropopause is formed using 30 yr of reanalyses. Composite analysis of potential vorticity and meridional fluxes of wave activity show that RWB in the SH can be divided into two broad categories: anticyclonic and cyclonic events. While there is only weak asymmetry in the meridional direction and most events cannot be classified as equatorward or poleward in terms of the potential vorticity structure, the position and structure of the fluxes associated with equatorward breaking differs from those of poleward breaking. Anticyclonic breaking is more common than cyclonic breaking, except on the lower isentrope examined (320 K). There are marked differences in the seasonal variations of RWB on the two surfaces, with a winter minimum for RWB around 350 K but a summer minimum for RWB around 330 K. These seasonal variations are due to changes in the location of the tropospheric jets and dynamical tropopause. During winter the subtropical jet and tropopause at 350 K are collocated in the Australian–South Pacific Ocean region, resulting in a seasonal minimum in the 350-K RWB. During summer the polar front jet and 330-K tropopause are collocated over the Southern Atlantic and Indian Oceans, inhibiting RWB in this region.

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