Ocean tides around New Zealand

Abstract

The distribution of amplitude and phase for eight ocean tidal constituents (M₂, S₂, N₂, K₂, K₁, O₁, P₁, Q₁) is presented as tidal maps for the New Zealand area. The distribution was calculated using a barotropic tidal model driven by TOPEX/ Poseidon data on the outer ocean boundaries. The maps exhibit the known features of the tides in this area such as a complete rotation of the semi‐diurnal tides around New Zealand and the reduced spring‐neap variations on the east coast. They also point out several new features for which there are few or no observations, such as diurnal trapped waves and shelf waves. A comparison of the model results with observations shows that sea level errors are within 0.1 m in amplitude and 10° in phase for the largest constituents at all locations, including sites where the data are of low quality and where the geometry is not adequately resolved. For locations where the geometry is adequately represented and the observations are of high quality, sea level errors are within 0.02 m in amplitude and 7° in phase. These results represent the most accurate and highest resolution calculations of tides and currents yet attained for this area.

Keywords:

• tides
• Harmonic Model
• TOPEX/ Poseidon
• New Zealand