scholarly journals Interdecadal Variability of the Eastward Current in the South China Sea Associated with the Summer Asian Monsoon

2010 ◽  
Vol 23 (22) ◽  
pp. 6115-6123 ◽  
Author(s):  
Guihua Wang ◽  
Chunzai Wang ◽  
Rui Xin Huang
Keyword(s):  
South China Sea ◽  
Wind Stress ◽  
South China ◽  
Asian Monsoon ◽  
Interdecadal Variability ◽  
Wind Stress Curl ◽  
China Sea ◽  
Ocean Data Assimilation ◽  
Southward Shift ◽  
Ocean Gyre

Abstract Based on the Simple Ocean Data Assimilation (SODA) dataset and three types of Sverdrup streamfunction, an interdecadal variability of the eastward current in the middle South China Sea (SCS) during summer is identified. Both the pattern and strength of the summer Asian monsoon wind stress curl over the SCS contribute to the interdecadal variability of this current. From 1960 to 1979, the monsoon intensified and the zero wind stress curl line shifted southward. Both the core of positive wind stress curl in the northern SCS and the negative curl in the southern SCS moved southward and thus induced a southward shift of both the southern anticyclonic and northern cyclonic gyres, resulting in a southward displacement of the eastward current associated with these two gyres. In the meantime, the southern (northern) SCS anticyclonic (cyclonic) ocean gyre weakened (strengthened) and therefore also induced the southward shift of the eastward current near the intergyre boundary. In contrast, the eastward current shifted northward from 1980 to 1998 because the monsoon relaxed and the zero wind stress curl line shifted northward. After 1998, the eastward jet moved southward again as the zero wind stress curl line shifted southward and the SCS monsoon strengthened. The eastward current identified from the baroclinic streamfunction moved about 1.7° more southward than that from the barotropic streamfunction, indicating that the meridional position of the eastward current is depth dependent.

Formation and Dynamics of a Long-Lived Eddy Train in the South China Sea: A Modeling Study

2017 ◽  
Vol 47 (11) ◽  
pp. 2793-2810 ◽  
Author(s):  
Zhongya Cai ◽  
Jianping Gan
Keyword(s):  
South China Sea ◽  
Wind Stress ◽  
South China ◽  
Northern South China Sea ◽  
Anticyclonic Eddy ◽  
The South China Sea ◽  
The South ◽  
Wind Stress Curl ◽  
China Sea ◽  
Anticyclonic Eddies

AbstractA process-oriented numerical modeling study was conducted to investigate the formation and underlying forcing of an anticyclonic eddy train observed in the northern South China Sea. Observations showed that long-lived anticyclonic eddies formed an eddy train along an eastward separated jet across the northern South China Sea in summer. The eddy train plays a critical role in regulating ocean circulation in the region. Forced by the southwesterly monsoon and prevailing dipole wind stress curl in the summer, the northward coastal jet separates from the west boundary of the South China Sea basin and overshoots northeastward into the basin. The anticyclonic recirculation of the separated jet forms the first anticyclonic eddy in the eddy train. The jet meanders downstream with a strong negative shear vorticity that forms a second and a third anticyclonic eddy along the jet’s path. These three eddies form the eddy train. These eddies weaken gradually with depth from surface, but they can extend to approximately 500 m deep. The inherent stratification in the region regulates the three-dimensional scale of the anticyclonic eddies and constrains their intensity vertical extension by weakening the geostrophic balance within these eddies. Analyses of the vorticity balance indicate that the eddy train’s negative vorticity originates from the beta effect of northward western boundary current and from the subsequent downstream vorticity advection in the jet. The jet separation is a necessary condition for the formation of the eddy train, and the enhanced stratification, increased summer wind stress, and associated negative wind stress curl are favorable conditions for the formation of the anticyclonic eddies.

Late Quaternary coccolith records in the South China Sea and East Asian monsoon dynamics

2013 ◽  
Vol 111 ◽  
pp. 88-96 ◽  
Author(s):  
Xiang Su ◽  
Chuanlian Liu ◽  
Luc Beaufort ◽  
Jun Tian ◽  
Enqing Huang
Keyword(s):  
South China Sea ◽  
South China ◽  
Asian Monsoon ◽  
East Asian Monsoon ◽  
Late Quaternary ◽  
East Asian ◽  
The South China Sea ◽  
The South ◽  
China Sea ◽  
Monsoon Dynamics

scholarly journals Correlation of Near-Inertial Wind Stress in Typhoon and Typhoon-Induced Oceanic Near-Inertial Kinetic Energy in the Upper South China Sea

Atmosphere ◽  
2019 ◽  
Vol 10 (7) ◽  
pp. 388
Author(s):  
Li ◽  
Xu ◽  
Liu ◽  
He ◽  
Chen ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
South China Sea ◽  
Wind Energy ◽  
Wind Stress ◽  
South China ◽  
Translation Speed ◽  
China Sea ◽  
Typhoon Track ◽  
Upper South ◽  
Inertial Currents

The correlation of near-inertial wind stress (NIWS) in typhoon and typhoon-induced oceanic near-inertial kinetic energy (NIKE) in the upper South China Sea (SCS) is investigated through reanalysis data and an idealized typhoon model. It is found that the typhoon-induced oceanic near-inertial currents are primarily induced by the NIWS, which may contribute to about 80% of the total NIKE induced by typhoon. The intensities and distributions of NIWS in most typhoons are consistent with the magnitudes and features of NIKE. The NIWS and the NIKE along the typhoon track have positive correlations with the maximum wind speed of a typhoon, but there is an optimal translation speed for NIWS, at which the wind energy of the near-inertial band reaches its maximum. In the idealized typhoon model, a cluster of high-value centers of NIWS appear along the typhoon track, but there is only one high-value center for the near-inertial currents. The maximum NIWS arrives about 15 hours prior to the maximum near-inertial current. The distribution of NIWS is apparently asymmetric along the typhoon track, which may be due to the smaller eastward component of wind energy.

scholarly journals The Changing Influences of ENSO and the Pacific Meridional Mode on Mesoscale Eddies in the South China Sea

2019 ◽  
Vol 32 (3) ◽  
pp. 685-700 ◽  
Author(s):  
Pengfei Tuo ◽  
Jin-Yi Yu ◽  
Jianyu Hu
Keyword(s):  
South China Sea ◽  
Wind Stress ◽  
South China ◽  
Southern Oscillation ◽  
The South China Sea ◽  
Eddy Correlation ◽  
The South ◽  
Vector Method ◽  
China Sea ◽  
The Pacific

This study finds that the correlation between El Niño–Southern Oscillation (ENSO) and the activity of mesoscale oceanic eddies in the South China Sea (SCS) changed around 2004. The mesoscale eddy number determined from satellite altimetry observations using a geometry of the velocity vector method was significantly and negatively correlated with the Niño-3.4 index before 2004, but the correlation weakened and became insignificant afterward. Further analyses reveal that the ENSO–eddy relation is controlled by two major wind stress forcing mechanisms: one directly related to ENSO and the other indirectly related to ENSO through its subtropical precursor—the Pacific meridional modes (PMMs). Both mechanisms induce wind stress curl variations over the SCS that link ENSO to SCS eddy activities. While the direct ENSO mechanism always induces a negative ENSO–eddy correlation through the Walker circulation, the indirect mechanism is dominated by the northern PMM (nPMM), resulting in a negative ENSO–eddy correlation before 2004, and by the southern PMM (sPMM) after 2004, resulting in a positive ENSO–eddy correlation. As a result, the direct and indirect mechanisms enhance each other to produce a significant ENSO–eddy relation before 2004, but they cancel each other out, resulting in a weak ENSO–eddy relation afterward. The relative strengths of the northern and southern PMMs are the key to determining the ENSO–eddy relation and may be related to a phase change of the interdecadal Pacific oscillation.

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