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

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.

The East Sea (Japan Sea) in Change: A Story of Dissolved Oxygen

1999 ◽  
Vol 33 (1) ◽  
pp. 15-22 ◽  
Author(s):  
Kyung-Ryul Kim ◽  
Kuh Kim ◽  
Dong-Jin Kang ◽  
Sun Young Park ◽  
Mi-Kyung Park ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
Ventilation System ◽  
Japan Sea ◽  
East Sea ◽  
Future Research ◽  
Intermediate Water ◽  
Chemical Tracers ◽  
Marginal Seas ◽  
East Asian Marginal Seas ◽  
Water Formation

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.

Holocene sedimentation in the Hupo Trough of the southwestern East Sea (Japan Sea) and development of the East Korea Warm Current

The Holocene ◽  
2021 ◽  
pp. 095968362110032
Author(s):  
Boo-Keun Khim ◽  
Sunghan Kim ◽  
Yu-Hyeon Park ◽  
Jongmin Lee ◽  
Sangbeom Ha ◽  
...  
Keyword(s):  
Grain Size ◽  
Japan Sea ◽  
East Sea ◽  
Eastern Coast ◽  
Size Change ◽  
Sediment Properties ◽  
Warm Current ◽  
The Holocene ◽  
Mean Grain Size ◽  
East Korea Warm Current

Various sediment properties, such as mean grain size, total organic carbon, total nitrogen, C/N ratio, CaCO3, and biogenic opal content, were analyzed for a box core (BC02; 45 cm long) and a gravity core (GC02; 628 cm long), which were collected from the western margin of the Hupo Trough located off the eastern coast of Korea. The study area has been affected by the East Korea Warm Current (EKWC), a branch of the Tsushima Warm Current (TWC). The analytical results obtained for BC02 and the upper part of GC02 were in agreement, affirming the core-top preservation of GC02. Based on the corrected calibrated AMS 14C dates, the sedimentation rate of GC02 changed abruptly at ~8.2 ka from ~4.0–10.2 cm/kyr in the lower part to ~56.6–91.0 cm/kyr in the middle to upper part. This corresponds to the lithologic change from sandy mud to mud sediments showing the mean grain size change from 6.9 to 46.0 μm. Diverse paleoceanographic proxies representing the surface water condition exhibited varying degree of change at ~8.2 ka, after which all the properties remain almost unchanged, implying stable and continuous depositional conditions following the complete development of the EKWC. Furthermore, it indicated that the sediment depositional conditions in the Hupo Trough in response to the EKWC might have stabilized at ~8.2 ka since the opening of the Korea Strait during the Holocene sea level rise. Moreover, microfossil data from previous studies on the establishment of the TWC in the East Sea (Japan Sea) support our interpretation that the sediment properties revealed the Holocene development of the EKWC in the Hupo Trough.

scholarly journals High-salinity intermediate water of the Japan Sea in the eastern Japan Basin

2001 ◽  
Vol 106 (C6) ◽  
pp. 11437-11450 ◽  
Author(s):  
Tatsuro Watanabe ◽  
Mitsuyuki Hirai ◽  
Haruya Yamada
Keyword(s):  
High Salinity ◽  
Japan Sea ◽  
Intermediate Water ◽  
Japan Basin ◽  
The Japan Sea ◽  
Eastern Japan

Coherent ranging with Envisat radar altimeter: A new perspective in analyzing altimeter data using Doppler processing

2013 ◽  
Vol 139 ◽  
pp. 271-276 ◽  
Author(s):  
R. Abileah ◽  
J. Gómez-Enri ◽  
A. Scozzari ◽  
S. Vignudelli
Keyword(s):  
Altimeter Data ◽  
Radar Altimeter ◽  
New Perspective

scholarly journals Anatomy of a Cyclonic Eddy in the Kuroshio Extension Based on High-Resolution Observations

Atmosphere ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 553 ◽  
Author(s):  
Yongchui Zhang ◽  
Xi Chen ◽  
Changming Dong
Keyword(s):  
High Resolution ◽  
Mixed Layer ◽  
Kuroshio Extension ◽  
Mesoscale Eddies ◽  
Cyclonic Eddy ◽  
Intermediate Water ◽  
Dipole Structure ◽  
Significant Difference ◽  
The Kuroshio ◽  
Main Thermocline

Mesoscale eddies are common in the ocean and their surface characteristics have been well revealed based on altimetric observations. Comparatively, the knowledge of the three-dimensional (3D) structure of mesoscale eddies is scarce, especially in the open ocean. In the present study, high-resolution field observations of a cyclonic eddy in the Kuroshio Extension have been carried out and the anatomy of the observed eddy is conducted. The temperature anomaly exhibits a vertical monopole cone structure with a maximum of −7.3 °C located in the main thermocline. The salinity anomaly shows a vertical dipole structure with a fresh anomaly in the main thermocline and a saline anomaly in the North Pacific Intermediate Water (NPIW). The cyclonic flow displays an equivalent barotropic structure. The mixed layer is deep in the center of the eddy and thin in the periphery. The seasonal thermocline is intensified and the permanent thermocline is upward domed by 350 m. The subtropical mode water (STMW) straddled between the seasonal and permanent thermoclines weakens and dissipates in the eddy center. The salinity of NPIW distributed along the isopycnals shows no significant difference inside and outside the eddy. The geostrophic relation is approximately set up in the eddy. The nonlinearity—defined as the ratio between the rotational speed to the translational speed—is 12.5 and decreases with depth. The eddy-wind interaction is examined by high resolution satellite observations. The results show that the cold eddy induces wind stress aloft with positive divergence and negative curl. The wind induced upwelling process is responsible for the formation of the horizontal monopole pattern of salinity, while the horizontal transport results in the horizontal dipole structure of temperature in the mixed layer.

Sign in / Sign up

Export Citation Format

Share Document