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

Abstract

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.

Quantifying the Degree of Eddy Quasi‐Geostrophy by Generalizing Rossby Deformation

“…To enhance our understanding of the significance of the proposed eddy QG index in eddy dynamic research, we conduct a case study on the variation of the index during an eddy merging/splitting event, as presented in Figure 7. Eddy merging and splitting are frequently observed complex dynamical processes in the ocean (e.g., Li et al., 2016; Tian et al., 2021; H. Wang et al., 2019). Figures 7a–7c display three snapshots of eddies during April 1–21, 1997, which exhibit simultaneous occurrences of eddy merging and splitting (marked with purple and dark blue boxes as A1 and A2, respectively), as also reported by Li et al.…”

Ocean Exchange and Circulation

“…Other papers in this Special Issue reflect the large interest and importance of mesoscale eddies in a number of semi-enclosed seas of the world ocean. A detailed census of mesoscale eddies and their generation and migration within the South China Sea is presented by Wang et al [3]. A combined use of satellite measurement data and Hybrid Coordinate Ocean Model (HYCOM) reanalysis data, together with the self-organizing map (SOM) method, was used to investigate the east branch of the Kuroshio bifurcation where four coherent patterns associated with mesoscale eddies in the Pacific Ocean were found [4].…”

Clustering Complex Trajectories Based on Topologic Similarity and Spatial Proximity: A Case Study of the Mesoscale Ocean Eddies in the South China Sea

“…When mesoscale ocean eddies migrate through their major migration corridors, the intra-eddy interaction intensifies and, subsequently, eddies tend to split and/or merge more [41]. New eddies can also be generated as a result of the splitting or merging processes [42]. The intra-eddy interaction, thus the splitting and merging processes, could be attributed to wind stress and the Kuroshio intrusion in the southwest of Taiwan Island (R1) [26,29], the wind stress curl formed by the interaction between wind and topography in the northwest and southwest of Luzon Island (R2, R3) [42], and the strong eastward jet shooting away from the coast in the southeast of Vietnam (R5) [40].…”

“…New eddies can also be generated as a result of the splitting or merging processes [42]. The intra-eddy interaction, thus the splitting and merging processes, could be attributed to wind stress and the Kuroshio intrusion in the southwest of Taiwan Island (R1) [26,29], the wind stress curl formed by the interaction between wind and topography in the northwest and southwest of Luzon Island (R2, R3) [42], and the strong eastward jet shooting away from the coast in the southeast of Vietnam (R5) [40]. The strong eastward jet may also significantly interrupt the movement of the water masses in the southeast of Vietnam, and forces more eddies to either merge or split.…”