A Barotropic Model of Tides along Australia's Southern Shelves

Guennadi Platov and John F. Middleton*

Department of Applied Mathematics Report 00/22

UNSW, Sydney 2052

 Some details

Abstract

Depth-averaged numerical results are obtained for the (M₂, S₂, K₁, O₁) constituents along Australia's southern shelves and results compared with analyses of near coastal sea level data. Results are obtained in two ways. First, by prescribing sea level along open boundaries using globally assimilated sea level data and second, by prescribing sea level along both open boundaries and everywhere the water depth exceeds 1000m. The latter method generally leads to superior results and mimics the changes in phase and four-fold amplification of sea level for the M₂ and S₂ constituents and within the South Australian Gulfs. The amplification is ascribed to a 1/4 wave resonance and the combined effects of these tides can lead to sea level and current oscillations of up to 80cm and 40cm/s in Spencer Gulf. On the adjacent shelves, the currents are typically 2cm/s or less. For the K₁ and O₁ constituents, the resonance is weaker, although the current variability of 5-8cm/s is found both within the Gulfs and on the adjacent shelf and for water depths of 100-1000m. Tidal currents to the west of the Gulfs region are again less than 2cm/s.

Co-range (dashed; cm) and co-phase (solid; degrees) of the  M2 tide as predicted for the Gulf's region using Deep Ocean Forcing.