Three mesoscale eddy detection and tracking methods: Assessment for the South China Sea

2020 ◽  
Author(s):  
Tao Xing ◽  
Yikai Yang
Keyword(s):  
South China Sea ◽  
South China ◽  
Mesoscale Eddy ◽  
The South China Sea ◽  
The South ◽  
China Sea ◽  
Advantages And Disadvantages ◽  
Detection And Tracking ◽  
Eddy Characteristics ◽  
Eddy Detection

AbstractComplex topography and the Kuroshio eddy shedding process produce active mesoscale eddy activity in the South China Sea (SCS). Three eddy detection and tracking methods, the Okubo-Weiss (O-W), Vector-Geometry (V-G), and Winding-Angle (W-A) algorithms, have been widely applied for eddy identification. This study provides a comprehensive assessment of the O-W, V-G and W-A methods in the SCS, including their detection, statistical analysis, and tracking capabilities. The mean successful detection rates (SDRs) of the O-W, V-G and W-A methods are 51.9%, 56.8% and 61.4%, respectively. The O-W and V-G methods preferentially detect eddies with medium radii (1/2°-1°), while the W-A method is tend to be larger radii (>1°). The V-G method identifies an excessive number of weak (radius<1/3°) eddy-like structures in the SCS, accounting for 48.2% of the total eddy number. The highest mean excessive detection rate (EDR) of the V-G method biases the data on eddy number, probability and propagation direction. With the lowest mean successful tracking rate (STR), the O-W method might not be suitable for tracking long-lived eddies in the SCS. The V-G method performs well regarding the over-tracking issue and has the lowest mean questionable tracking rate (QTR) of 1.1%. Among the three methods, the W-A method tracks eddies most accurately, with the highest mean STR of 80.6%. Overall, the W-A method produces reasonable statistical eddy characteristics and eddy tracking results. Each method has advantages and disadvantages, and researchers should choose wisely according to their needs.

scholarly journals Extraction of spatial-temporal rules from mesoscale eddies in the South China Sea based on rough set theory

Ocean Science ◽  
2011 ◽  
Vol 7 (6) ◽  
pp. 835-849 ◽  
Author(s):  
Y. Du ◽  
X. Fan ◽  
Z. He ◽  
F. Su ◽  
C. Zhou ◽  
...  
Keyword(s):  
South China Sea ◽  
Set Theory ◽  
Rough Set ◽  
South China ◽  
Rough Set Theory ◽  
Mesoscale Eddy ◽  
The South China Sea ◽  
The South ◽  
Long Distance ◽  
China Sea

Abstract. In this paper, a rough set theory is introduced to represent spatial-temporal relationships and extract the corresponding rules from typical mesoscale-eddy states in the South China Sea (SCS). Three decision attributes are adopted in this study, which make the approach flexible in retrieving spatial-temporal rules with different features. The results demonstrate that this approach is effective, and therefore provides a powerful approach to forecasts in the future studies. Spatial-temporal rules in the SCS indicate that warm eddies following the rules are generally in the southeastern and central SCS around 2000 m isobaths in winter. Their intensity and vorticity are weaker than those of cold eddies. They usually move a shorter distance. By contrast, cold eddies are in 2000 m and deeper regions of the southwestern and northeastern SCS in spring and fall. Their intensity and vorticity are strong. Usually they move a long distance. In winter, a few rules are followed by cold eddies in the northern tip of the basin and southwest of Taiwan Island rather than warm eddies, indicating cold eddies may be well-regulated in the region. Several warm-eddy rules are achieved west of Luzon Island, indicating warm eddies may be well-regulated in the region as well. Otherwise, warm and cold eddies are distributed not only in the jet flow off southern Vietnam induced by intraseasonal wind stress in summer-fall, but also in the northern shallow water, which should be a focus of a future study.

Impact of assimilating altimeter data on eddy characteristics in the South China Sea

2020 ◽  
Vol 155 ◽  
pp. 101704
Author(s):  
J. Xie ◽  
M. De Vos ◽  
L. Bertino ◽  
J. Zhu ◽  
F. Counillon
Keyword(s):  
South China Sea ◽  
South China ◽  
The South China Sea ◽  
Altimeter Data ◽  
The South ◽  
China Sea ◽  
Eddy Characteristics

Statistical analysis of mesoscale eddy propagation velocity in the South China Sea deep basin

2020 ◽  
Vol 39 (11) ◽  
pp. 91-102
Author(s):  
Runqi Huang ◽  
Lingling Xie ◽  
Quanan Zheng ◽  
Mingming Li ◽  
Peng Bai ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
South China Sea ◽  
South China ◽  
Propagation Velocity ◽  
Mesoscale Eddy ◽  
The South China Sea ◽  
The South ◽  
Deep Basin ◽  
China Sea

scholarly journals Extraction of spatial-temporal rules from mesoscale eddies in the South China Sea Based on rough set theory

2011 ◽  
Vol 8 (3) ◽  
pp. 1261-1300
Author(s):  
Y. Du ◽  
X. Fan ◽  
Z. He ◽  
F. Su ◽  
C. Zhou ◽  
...  
Keyword(s):  
South China Sea ◽  
Set Theory ◽  
Rough Set ◽  
South China ◽  
Rough Set Theory ◽  
Mesoscale Eddy ◽  
The South China Sea ◽  
The South ◽  
China Sea ◽  
Decision Attributes

Abstract. In this paper, a rough set theory is introduced to represent spatial-temporal relationships and extract the corresponding rules from typical mesoscale-eddy states in the South China Sea (SCS). Three decision attributes are adopted in this study, which make the approach flexible in retrieving spatial-temporal rules with different features. Spatial-temporal rules of typical states in the SCS are extracted as three decision attributes, which then are confirmed by the previous works. The results demonstrate that this approach is effective in extracting spatial-temporal rules from typical mesoscale-eddy states, and therefore provides a powerful approach to forecasts in the future. Spatial-temporal rules in the SCS indicate that warm eddies following the rules are generally in the southeastern and central SCS around 2000 m isobaths in winter. Their intensity and vorticity are weaker than those of cold eddies. They usually move a shorter distance. By contrast, cold eddies are in 2000 m-deeper regions of the southwestern and northeastern SCS in spring and fall. Their intensity and vorticity are strong. Usually they move a long distance. In winter, a few rules are followed by cold eddies in the northern tip of the basin and southwest of Taiwan Island rather than warm eddies, indicating cold eddies may be well-regulated in the region. Several warm-eddy rules are achieved west of Luzon Island, indicating warm eddies may be well-regulated in the region as well. Otherwise, warm and cold eddies are distributed not only in the jet flow off southern Vietnam induced by intraseasonal wind stress in summer-fall, but also in the northern shallow water, which should be a focus of future study.

scholarly journals A Census of the 1993–2016 Complex Mesoscale Eddy Processes in the South China Sea

Water ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1208 ◽  
Author(s):  
Huimeng Wang ◽  
Yunyan Du ◽  
Fuyuan Liang ◽  
Yong Sun ◽  
Jiawei Yi
Keyword(s):  
South China Sea ◽  
South China ◽  
Mesoscale Eddy ◽  
The South China Sea ◽  
Cyclonic Eddy ◽  
The South ◽  
China Sea ◽  
Complex Processes ◽  
Seabed Topography ◽  
Characteristic Points

Mesoscale eddy process with at least one splitting and/or merging event can be defined as either a complex process or a simple process. Investigation of the difference between these two categories could provide new insights into how different factors, such as the seabed topography, Kuroshio intrusion, and winds, affect the origin, migration, and decay of the mesoscale eddies. This study compared the characteristics of the complex against the simple eddy processes in the South China Sea (SCS) from 1993 to 2016. We comprehensively analyzed the eddy processes with regards to their characteristic points, trajectories, and networks. The simple and complex processes share many similarities but do show significantly different behaviors. Both the simple and complex processes mainly start from the eastern SCS. However, the complex processes mainly vanish in the western SCS whereas the simple processes disappear almost everywhere across the SCS. The complex processes last longer and migrate more than the simple processes. Lastly, the complex processes mainly move westward within the community. The complex processes can be further categorized into complex anticyclonic and cyclonic eddy processes. Spatially, the splitting and merging events mainly occur in the southwest of Taiwan, northwest of the Luzon Island, and the southeast of Vietnam. Temporally, the merging and splitting events mainly occur in the fall. The interaction among the communities reveals the different migration patterns of the complex anticyclonic and cyclonic eddy processes in the SCS.

Prospects for development of Vietnam underwater springs

2021 ◽  
pp. 140-144
Author(s):  
Yu.V. Kirichenko ◽  
Tran Thien Ngo Quy
Keyword(s):  
South China Sea ◽  
South China ◽  
Pacific Coast ◽  
The South China Sea ◽  
Shelf Zone ◽  
The South ◽  
China Sea ◽  
Advantages And Disadvantages ◽  
The Pacific ◽  
Coast Of Vietnam

The issues of the relevance of exploration and development of seabed deposits are considered. The article provides information on the history and composition of studies of solid mineral deposits carried out in the South China Sea by scientists of the Democratic Republic of Vietnam. The oceanographic and geological characteristics of the Pacific coast of Vietnam, its shelf and continental slope are given. The conditions that form placer deposits in the exclusive economic zone of Vietnam are given, and their brief description is given. Examples of various placers in the shelf zone, their features are given, and schematic diagrams of occurrence are given. The dependence of the littoral width on the height of the tidal wave and the angle of inclination of the shelf is analyzed. Proposals are given on the possibility of developing alluvial deposits in the littoral zone using dry drilling equipment, the advantages and disadvantages of this technology are stated. The features of the influence of climatic conditions of the Pacific coast of Vietnam on the use of hydromechanized technologies in the development of underwater placers are noted. Emphasis is placed on maintaining the ecological balance in the fields of development and the continuation of further research in the South China Sea.

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