scholarly journals Deep Circulation in the South China Sea Simulated in a Regional Model

2019 ◽  
Author(s):  
Xiaolong Zhao ◽  
Chun Zhou ◽  
Xiaobiao Xu ◽  
Ruijie Ye ◽  
Jiwei Tian ◽  
...  
Keyword(s):  
South China Sea ◽  
Spatial Structure ◽  
South China ◽  
The South China Sea ◽  
Northwest Pacific ◽  
The South ◽  
China Sea ◽  
Deep Circulation ◽  
Mixing Parameters ◽  
Circulation In The Scs

Abstract. The South China Sea (SCS) is the largest marginal sea in the northwest Pacific Ocean. In this study, deep circulation in the SCS is investigated using results from eddy-resolving, regional simulations using the Hybrid Coordinate Ocean Model (HYCOM) verified by continuous current-meter observations. Analysis of these results provides a detailed spatial structure and temporal variability of the deep circulation in the SCS. The major features of the SCS deep circulation are a basin-scale cyclonic gyre and a concentrated deep western boundary current (DWBC). Transport of the DWBC is ∼ 2 Sv at 16.5° N with a width of ∼53 km. Flowing southwestward, the narrow DWBC becomes weaker with a wider range. The model results reveal the existence of 80- to 120-day oscillation in the deep northeastern circulation and the DWBC, which are also the areas with elevated eddy kinetic energy. This intraseasonal oscillation propagates northwestward with a velocity amplitude of ∼ 1.0 to 1.5 cm s-1. The distribution of mixing parameters in the deep SCS plays a role in both spatial structure and volume transport of the deep circulation. Compared with the northern shelf of the SCS with the Luzon Strait, deep circulation in the SCS is more sensitive to the large vertical mixing parameters of the Zhongsha Island Chain area.

scholarly journals Tropical Cyclone–Induced Ocean Response: A Comparative Study of the South China Sea and Tropical Northwest Pacific*,+

2015 ◽  
Vol 28 (15) ◽  
pp. 5952-5968 ◽  
Author(s):  
Wei Mei ◽  
Chun-Chi Lien ◽  
I.-I. Lin ◽  
Shang-Ping Xie
Keyword(s):  
South China Sea ◽  
Mixed Layer ◽  
South China ◽  
Regional Difference ◽  
Chlorophyll Concentration ◽  
The South China Sea ◽  
Northwest Pacific ◽  
The South ◽  
China Sea ◽  
Sst Cooling

Abstract The thermocline shoals in the South China Sea (SCS) relative to the tropical northwest Pacific Ocean (NWP), as required by geostrophic balance with the Kuroshio. The present study examines the effect of this difference in ocean state on the response of sea surface temperature (SST) and chlorophyll concentration to tropical cyclones (TCs), using both satellite-derived measurements and three-dimensional numerical simulations. In both regions, TC-produced SST cooling strongly depends on TC characteristics (including intensity as measured by the maximum surface wind speed, translation speed, and size). When subject to identical TC forcing, the SST cooling in the SCS is more than 1.5 times that in the NWP, which may partially explain weaker TC intensity on average observed in the SCS. Both a shallower mixed layer and stronger subsurface thermal stratification in the SCS contribute to this regional difference in SST cooling. The mixed layer effect dominates when TCs are weak, fast-moving, and/or small; and for strong and slow-moving TCs or strong and large TCs, both factors are equally important. In both regions, TCs tend to elevate surface chlorophyll concentration. For identical TC forcing, the surface chlorophyll increase in the SCS is around 10 times that in the NWP, a difference much stronger than that in SST cooling. This large regional difference in the surface chlorophyll response is at least partially due to a shallower nutricline and stronger vertical nutrient gradient in the SCS. The effect of regional difference in upper-ocean density stratification on the surface nutrient response is negligible. The total annual primary production increase associated with the TC passage estimated using the vertically generalized production model in the SCS is nearly 3 times that in the NWP (i.e., 6.4 ± 0.4 × 1012 versus 2.2 ± 0.2 × 1012 g C), despite the weaker TC activity in the SCS.

On the dynamics of the South China Sea deep circulation

2013 ◽  
Vol 118 (3) ◽  
pp. 1206-1210 ◽  
Author(s):  
Jian Lan ◽  
Ningning Zhang ◽  
Yu Wang
Keyword(s):  
South China Sea ◽  
South China ◽  
The South China Sea ◽  
The South ◽  
China Sea ◽  
Deep Circulation

scholarly journals Impact of Intraseasonal Oscillations on the Activity of Tropical Cyclones in Summer Over the South China Sea: Nonlocal Tropical Cyclones

2020 ◽  
Vol 8 ◽  
Author(s):  
Zheng Ling ◽  
Yuqing Wang ◽  
Guihua Wang ◽  
Hailun He
Keyword(s):  
South China Sea ◽  
Tropical Cyclones ◽  
South China ◽  
Western Pacific Subtropical High ◽  
The South China Sea ◽  
Northwest Pacific ◽  
The South ◽  
China Sea ◽  
Typhoon Intensity ◽  
Intraseasonal Oscillations

In addition to tropical cyclones (TCs) locally formed in the South China Sea (SCS), there are also TCs that initially form over the Northwest Pacific (NWP) and move westward to enter the SCS (often called nonlocal TCs). It is unclear how those nonlocal TCs are modulated by the intraseasonal climate variability. In this study, the impacts of two types of intraseasonal oscillations, namely the Madden–Julian Oscillation (MJO) and the quasi-biweekly oscillation (QBWO), on nonlocally formed TCs over the SCS in summer (May–September) are analyzed based on best-track TC data and global reanalysis during 1979–2018. Results show that in the convective phases of both MJO and QBWO, the western Pacific subtropical high shifted more eastward, and more TCs entered the SCS. This is mainly because more TCs formed in the NWP in the convective phases of intraseasonal oscillations and the genesis locations of the NWP TCs shifted westward and closer to the SCS. In addition to TC count, intraseasonal oscillations also affected the intensity of nonlocal TCs entered the SCS, with the influence of QBWO being more significant than MJO. In the convectively active phases of QBWO (phases 2–5), 34 nonlocal TCs reached typhoon intensity, while only two nonlocal TCs reached typhoon intensity in the convectively inactive phases (phases 1, 6, 7, 8). Further analysis indicates that nonlocal TCs often moved with the northwestward propagating convective signals of QBWO, resulting in more and stronger TCs that entered the SCS in the convective phases of QBWO. The mean location that the nonlocal TC entered the SCS also shifted northward with the northward propagation of intraseasonal oscillations.

Progress on deep circulation and meridional overturning circulation in the South China Sea

2016 ◽  
Vol 59 (9) ◽  
pp. 1827-1833 ◽  
Author(s):  
DongXiao Wang ◽  
JinGen Xiao ◽  
YeQiang Shu ◽  
Qiang Xie ◽  
Ju Chen ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
The South China Sea ◽  
Meridional Overturning Circulation ◽  
The South ◽  
Overturning Circulation ◽  
China Sea ◽  
Deep Circulation ◽  
Meridional Overturning

Deep circulation in the South China Sea simulated in a regional model

2020 ◽  
Vol 70 (11) ◽  
pp. 1461-1473
Author(s):  
Xiaolong Zhao ◽  
Chun Zhou ◽  
Xiaobiao Xu ◽  
Ruijie Ye ◽  
Wei Zhao
Keyword(s):  
South China Sea ◽  
South China ◽  
Regional Model ◽  
The South China Sea ◽  
The South ◽  
China Sea ◽  
Deep Circulation
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