Analysis on the symmetry of tides at the Keelung and Kaohsiung ports

Wen Jye Juang*, Hsiang Mao Tseng, Hsien-Kuo Chang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The tides at both of the Keelung port (KL) and the Kaohsiung port (KH) that located at the north and south ends of Taiwan, respectively, exhibit interestingly symmetrical appearance. Applying the harmonic analysis on the yearly tidal records of both ports during 1989 ~ 1991, it is found that the causes are mainly due to the top three constituents: M2, K1 and Q1 are same, and the amplitudes are similar. Moreover, the phase lags of each of the constituents that evaluated by KH relative to KL is nearly constant. With those essential characteristics of constituents to form the synthetic tides for both of the ports, we further confirm that the carrier and the envelope are same, besides existing a phase lags of 60°, eq. a time lags of 8.61 hrs on the envelope. By the way of transforming the time lags into location difference, therefore, the wave group velocity is applied to estimate the propagation distance between KL and KH, so as to the characteristic width of the continental shelf which dominates the tidal appearance around the west coast of Taiwan. And it is about 698.3 km supposed the mean water depth of 60 m on the Taiwan Strait.

Original languageEnglish
Pages (from-to)335-341
Number of pages7
JournalJournal of the Chinese Institute of Civil and Hydraulic Engineering
Issue number4
StatePublished - 1 Dec 2014


  • Harmonic analysis
  • Synthetic tides
  • The characteristic width of continental shelf
  • The Taiwan Strait
  • Waves envelope

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