Rossby wave packets in baroclinic mean currents

Ping Chang, S. G.H. Philander

Research output: Contribution to journalArticle

30 Scopus citations

Abstract

A WKB description of the propagation of Rossby wave packets in a shallow water model of the tropical oceans indicates that the presence of the baroclinic mean currents can modify the characteristics of wave propagation significantly. For currents with weak latitudinal shear the effect of the current itself is less important than the effect of the associated variations in the depth of the thermocline, except near critical layers where waves are absorbed. For example, a westward current, and the associated shoaling of the thermocline towards the equator, can cause the speed of the long Rossby waves to decrease with decreasing latitude. (The speed increases towards the equator in the absence of mean currents.) Westward currents inhibit meridional propagation, but eastward currents enhance it. The amplification and decay of a wave packet as it propagates through a mean current are described in terms of these conservation of wave action. Implications of these results for the propagation of Rossby waves in the real ocean are discussed.

Original languageEnglish (US)
Pages (from-to)17-37
Number of pages21
JournalDeep Sea Research Part A, Oceanographic Research Papers
Volume36
Issue number1
DOIs
StatePublished - Jan 1989

All Science Journal Classification (ASJC) codes

  • Environmental Science(all)
  • Earth and Planetary Sciences(all)

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