Title page for etd-0803110-124203


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URN etd-0803110-124203
Author Yun-chiang Liao
Author's Email Address yunjiang_liao@yahoo.com.tw
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Department Marine Biotechnology and Resources
Year 2009
Semester 2
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title Anticyclonic eddies in northern South China Sea observed by drifters and satellite altimeter
Date of Defense 2010-07-15
Page Count 90
Keyword
  • drifter
  • South China Sea
  • Kuroshio
  • sea level anomaly
  • eddy
  • Abstract Satellite-tracked surface drifter data from 1986 to 2008 acquired from NOAA/AOML and the sea-level anomaly (SLA) data of AVISO from 1992-2008 were used in this study to investigate the mesoscale anticyclonic eddies in the northern South China Sea (SCS) and Luzon Strait. A comparison of the concurrent drifter trajectories and SLA for two eddy events (2003/12~2004/02 and 2004/11~2005/01) indicates good agreement between the two datasets. From historical SLA data (1992-2008) it is found that 78 anticyclonic eddies can be identified in the studied region. The number of occurrence is highest in 1994, 1996, 2001 and 2004, and is lowest in 1998. This result is likely due to the ENSO event and the associated wind lessening in the SCS. Most eddies were generated off southwestern Taiwan coast, northern SCS and west of Luzon Strait. During northeastern monsoon the average life time of eddies is 66.88 days, and the average sea level height difference is 10-20 cm, occasionally reached a maximum value of over 30 cm. During southwestern monsoon eddies have an average lifetime of 51.43 days, and the average sea level height difference is mostly less than 15 cm. In particular, eddies off the southwestern Taiwan coast have the characteristics of lower sea level height difference and translational speed. Location of eddy generation has a marked seasonal variation. During northeastern monsoon, most eddies were concentrated in northern Luzon Strait, propagating longer distance toward the west along the continental shelf, even reaching 112°E. On the other hand, eddies generated during the southwestern monsoon can only reach 118°E. Statistical results indicate a linear relationship exists between the sea level height difference and the life time for eddies, implying that stronger eddies are more long-lived. Finally, from drifter tracks it can be found that as Kuroshio penetrates through the Luzon Strait and forms a loop current off the southwestern Taiwan coast. Subsequently, eddies could often be identified from the SLA data. Therefore, it can be conjectured that in the northern SCS anticyclone are often shed from the Luzon Strait by Kuroshio penetration.
    Advisory Committee
  • Yu-huai Wang - chair
  • I-huan Lee - co-chair
  • Guan-yu Chen - co-chair
  • Ruo-shan Tseng - advisor
  • Files
  • etd-0803110-124203.pdf
  • indicate in-campus access immediately and off_campus access in a year
    Date of Submission 2010-08-03

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