Crescent-Shaped Low-Temperature Distribution along the Convex Topography in the Southeastern Edge of Taiwan Bank in Summer

Hung Jen Lee, Ming An Lee, Chia Ying Ho, Po Chun Hsu, Yi Chen Wang

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Various physical mechanisms of ocean upwelling usually occur near or along coastal regions worldwide. Five upwelling zones of unequal intensity are found around the Taiwan Strait, and the Taiwan Bank (TB) upwelling zone has the most prominent characteristics of low temperature. In this study, satellite images, shipboard ADCPs (acoustic Doppler current profilers), and CTDs (conductivity–temperature–depth measures) were analyzed to investigate the processes of cold water upwelling around the TB shoaling zone. In addition, the MITgcm numerical model and the flexible cu-bic spline technique were also employed, allowing us to better understand those processes. The model results suggested that a combination of Ekman transport and the centrifugal force, driven by the geostrophic South China Sea Warm Current (SCSWC), constitutes a physical mechanism to contribute the vigorous upwelling in the TB shoal zone. The upwelling is largely driven by Ekman transport. However, the centrifugal force may explain why the upwelling with a crescent<shaped distribution of low temperatures along the convex topography of the southeastern edge of the TB shoaling zone is more prominent than expected, as it tends toward the so<called gradient wind balance. Sudden relaxation of the friction force oc-curred because of the very sharp shelf break (20–60 m) and steep slope topography; a discontinuous velocity zone around the shelf break could also lead to vigorous cold water upwelling.

Original languageEnglish
Pages (from-to)2705-2723
Number of pages19
JournalJournal of Physical Oceanography
Volume52
Issue number11
DOIs
StatePublished - Oct 2022

Keywords

  • Eddies
  • Ekman pumping/transport
  • Ocean circulation
  • Ocean models
  • Oceanic mixed layer
  • Regional models

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