A three-dimensional model of tidal currents in the mouth of the Tagus estuary

André B. Fortunato, António M. Baptista, Richard A. Luettich

Research output: Contribution to journalArticlepeer-review

69 Scopus citations


Three-dimensional simulations of barotropic fides are used to investigate the complex circulation at the mouth of the Tagus estuary. Comparison with field data shows that elevations are well represented in the main area of interest, but velocities are slightly over-predicted due to a simplified treatment of intertidal flats. Model results show the existence of strong velocity phase lags (up to 1.75 hours for the semi-diurnal constituents) between the shallow areas and the deep channel. These phase lags are partially responsible for the generation by advective accelerations of a strong residual velocity field (velocities reach 0.5 m s-1) with well defined eddies. The interaction between the residual and tidal velocity fields in turn generates strong chaotic stirring. Localized sigma coordinates (LSC), a recently proposed method which allows the number of nodes per vertical to vary horizontally, are used for the first time in a three-dimensional application. A previously proposed criterion for the horizontal distribution of the total number of vertical nodes is shown to be inadequate when advective accelerations are important. However, with an alternative criterion, the use of LSC reduces maximum errors by a factor of two relative to traditional sigma coordinates.

Original languageEnglish (US)
Pages (from-to)1689-1714
Number of pages26
JournalContinental Shelf Research
Issue number14
StatePublished - Dec 1997
Externally publishedYes

ASJC Scopus subject areas

  • Oceanography
  • Aquatic Science
  • Geology


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