Vertical structure and evolution of the Luzon Warm Eddy

• Published in: Chinese journal of oceanology and limnology Vol. 28; no. 5; pp. 955 - 961
• Main Author: 陈更新 侯一筠 储小青 齐鹏
• Format: Journal Article
• Language: English
• Published: Heidelberg SP Science Press 01.09.2010; Springer Nature B.V
• Subjects: Altimeters; Argo浮标; Earth and Environmental Science; Earth Sciences; Eddies; Eddy kinetic energy; Empirical analysis; Energy distribution; Evolution; Evolutionary biology; High temperature; Kinematics; Kinetic energy; Marine; Normal distribution; Oceanography; Orthogonal functions; Temperature anomalies; Thermocline; TOPEX; Vertical profiles; Vortices; Water depth; 南海东北部; 垂直结构; 季节性特征; 时空演化; 测高卫星; 经验正交函数; South China Sea; ISEW, South China Sea; ISEW, China, People's Rep., Hainan; INW, Donghai Sea, Kuroshio Current; South China Sea; Luzon Warm Eddy; Argo; altimetry
• ISSN: 0254-4059; 2096-5508; 1993-5005; 2523-3521
• DOI: 10.1007/s00343-010-9040-3

Eddies are frequently observed in the northeastern South China Sea （SCS）. However, there have been few studies on vertical structure and temporal-spatial evolution of these eddies. We analyzed the seasonal Luzon Warm Eddy （LWE） based on Argo float data and the merged data products of satellite altimeters of Topex/Poseidon, Jason-1 and European Research Satellites. The analysis shows that the LWE extends vertically to more than 500 m water depth, with a higher temperature anomaly of 5℃ and lower salinity anomaly of 0.5 near the thermocline. The current speeds of the LWE are stronger in its uppermost 200 m, with a maximum speed of 0.6 m/s. Sometimes the LWE incorporates mixed waters from the Kuroshio Current and the SCS, and thus has higher thermohaline characteristics than local marine waters. Time series of eddy kinematic parameters show that the radii and shape of the LWE vary during propagation, and its eddy kinetic energy follows a normal distribution. In addition, we used the empirical orthogonal function （EOF） here to analyze seasonal characteristics of the LWE. The results suggest that the LWE generally forms in July, intensifies in August and September, separates from the coast of Luzon in October and propagates westward, and weakens in December and disappears in February. The LWE＇s westward migration is approximately along 19°N latitude from northwest of Luzon to southeast of Hainan, with a mean speed of 6.6 cm/s.