scholarly journals Impacts of the Madden–Julian Oscillation on the Summer South China Sea Ocean Circulation and Temperature

2013 ◽  
Vol 26 (20) ◽  
pp. 8084-8096 ◽  
Author(s):  
Guihua Wang ◽  
Zheng Ling ◽  
Renguang Wu ◽  
Changlin Chen
Keyword(s):  
South China Sea ◽  
Ocean Circulation ◽  
South China ◽  
Ocean Model ◽  
Ocean Modeling ◽  
Madden Julian Oscillation ◽  
Regional Ocean Modeling System ◽  
Wind Stress Curl ◽  
China Sea ◽  
The Impact

Abstract The present study investigates the impact of the Madden–Julian oscillation (MJO) on the South China Sea (SCS) in summer with three types of models: a theoretical Sverdrup model, a 1.5-layer reduced gravity model, and a regional ocean model [Regional Ocean Modeling System (ROMS)]. Results show that the ocean circulation in the SCS has an intraseasonal oscillation responding to the MJO. During its westerly phase, the MJO produces positive (negative) wind stress curl over the northern (southern) SCS and thus induces an enhanced cyclonic (anticyclonic) circulation in the northern (southern) SCS. This not only cools sea surface temperature (SST) but also decreases (increases) subsurface temperature in the northern (southern) SCS. During its easterly phase, the MJO basically produces a reversed but weaker influence on SCS ocean circulation and temperature. Thus, the MJO can have an imprint on the summer climatology of SCS circulation and temperature. The authors' analysis further indicates that the MJO's dynamic effect associated with wind is generally more important than its thermodynamic effect in modulating the regional ocean circulation and temperature. The present study suggests that the MJO is important for summer ocean circulation and temperature in the SCS.

Deepwater Steel Catenary Riser System Design for Lingshui 17-2 Project

2021 ◽  
Author(s):  
Ning He ◽  
Hu Yang ◽  
Fanli Xu ◽  
Yongming Cheng
Keyword(s):  
South China Sea ◽  
System Design ◽  
South China ◽  
Oil And Gas ◽  
Low Cost ◽  
Northern South China Sea ◽  
Steel Catenary Riser ◽  
China Sea ◽  
Scr System ◽  
The Impact

Abstract A riser is a key component for transporting produced oil and gas from the subsea wells to the surface production vessel. Through nearly 30 years of design and implementation, Steel Catenary Risers (SCRs) have been found to have the advantages of relatively low cost and good adaptability to floating platform’s motion. This paper investigates deepwater SCR system design for the Lingshui 17-2 (termed LS17-2) project. This paper first introduces a SCR system for the LS17-2 project. The field for this project is located in the northern South China Sea, with water depth of 1220m to 1560m. LS17-2 consists of a subsea production system, a deep-draft semi-submersible (SEMI), and an export riser/pipeline. The platform was designed to have a large storage capacity with a variable draft during its operation. Based on deepwater SCR engineering experience, the key SCR design challenges are summarized from the engineering executive perspective. The challenges to the SCR system design for the LS17-2 project include harsh environment condition in South China Sea and the impact on fatigue design for the requirement of 30-years’ service life. They call for design optimization and innovative ideas. The engineering design and analysis are discussed together solutions. To demonstrate the deepwater SCR system design for LS17-2 project, examples are provided to illustrate the challenges and solutions. The experience learned from this paper should have significant relevance to future SCR design.

scholarly journals The impact of the planetary β-effect on the tilting vertical structure of a mesoscale eddy

2018 ◽  
Author(s):  
Shengmu Yang ◽  
Jiuxing Xing ◽  
Shengli Chen ◽  
Jiwei Tian ◽  
Daoyi Chen
Keyword(s):  
South China Sea ◽  
South China ◽  
General Circulation ◽  
Vertical Structure ◽  
Mesoscale Eddy ◽  
Maximum Velocity ◽  
Circulation Model ◽  
Mesoscale Eddies ◽  
China Sea ◽  
The Impact

Abstract. Tilting mesoscale eddies in the South China Sea have been reported recently from observed field data. The mechanism of the dynamic process of the tilt, however, is not well understood. In this study, the influence of planetary β on the vertical structure of mesoscale eddies and its mechanism is investigated using theoretical analysis and numerical model experiments based on the MIT General Circulation Model (MITgcm). The results of the both approaches show that vertical motion due to the planetary β effect and nonlinear dynamics causes a pressure anomaly in the horizontal domain which triggers the tilt of the eddy axis. The tilting distance extends to be the radius of the eddy maximum velocity. In addition, the vertical stratification is another key factor in controlling the tilt of a mesoscale eddy. External forcings such as wind and inflow current are not considered in this study, and topography is included only in a realistic South China Sea model. Therefore, mesoscale eddies with large vertical depth should have the similar axis tilt character in open oceans under the β-effect.

Impacts of the Madden-Julian Oscillation on South China Sea Monsoon

2020 ◽  
Author(s):  
Qun Zhou ◽  
Lixin Wei
Keyword(s):  
South China Sea ◽  
South China ◽  
Meridional Circulation ◽  
East Asian ◽  
Winter Monsoon ◽  
Western Pacific ◽  
Madden Julian Oscillation ◽  
China Sea ◽  
The Western Pacific ◽  
Local Meridional Circulation

Abstract It is of great practical importance to understand the variability of the South China Sea (SCS) monsoon on intraseasonal time scales, since the anomalous enhancement of the SCS monsoon may exert serious impacts on the safety of offshore engineering and marine transportation. Our composite analysis shows that the SCS surface wind anomalies are considerably varying with the Madden-Julian Oscillation (MJO) eastward propagation. The SCS summer southwest monsoon tends to be stronger (weaker) in phases 5–8 (1–4) of MJO with the largest positive (negative) wind-speed anomalies when the MJO convection is centered in the western Pacific (far western Indian Ocean), suggesting the highest (lowest) probability of the gale over the SCS. The variation of the western Pacific Subtropical High (WPSH), induced by the variations of the local meridional circulation, is shown to play a crucial role in the MJO-SCS summer monsoon linkage. The SCS winter monsoon is also shown to be modulated by the MJO with strengthened (weakened) surface northeasterly in phases 5–6 (1–2). The extra-tropical East Asian trough and East Asian westerly jet associated with the local meridional circulation can well explain the changes of the MJO-SCS winter monsoon relationship. The opposite responses of the wind direction during the same phases of the MJO between summer and winter may be attributed to the discrepancy of meridional circulation related to the wintertime equatorward shift of the MJO convection. The present study indicates that the MJO could be taken into consideration when applying extended-range weather forecast over the SCS as the predictability of the MJO activity is up to 15–20 day currently.

scholarly journals A GIS-based method for depicting the characteristics of mesoscale eddies: a case study in the Northern South China Sea

2015 ◽  
Vol 52 (9) ◽  
pp. 746-756
Author(s):  
Ce Li ◽  
Yunyan Du ◽  
Fuyuan Liang ◽  
Jiawei Yi ◽  
V. Chris Lakhan
Keyword(s):  
South China Sea ◽  
South China ◽  
Northern South China Sea ◽  
Mesoscale Eddies ◽  
Ocean Model ◽  
Geographical Information ◽  
Naval Research ◽  
Evolutionary Processes ◽  
China Sea ◽  
Internal Structures

The paper presents a geographical information system (GIS)-based method for depicting the characteristics, particularly the internal structures and evolutionary processes, of mesoscale eddies. This was done by examining topologic relations among closed sea surface height (SSH) contours that were reconstructed from the Naval Research Laboratory Navy layered ocean model (NLOM). Different scenarios of the topological relations among the contour lines permitted the identification of the outermost outline of eddies and the depiction of the number of cores in each mesoscale oceanic eddy. With full consideration of the internal structure of the eddies, we then reconstructed the evolutionary processes of these eddies, and the results were compared with empirical observations on three long-lived mesoscale eddies in the northern South China Sea (SCS). Tracking results were similar, thereby validating our method as being efficient and robust in reconstructing mesoscale ocean eddies, especially their evolutionary processes based on their internal structures.

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