Description: This dataset represents the Tidal Ocean Current at the EEZ sclae. This is one of the FINAL environmental Varialbes created for the development of the Marine Environment Classification system. Tidal current climatologies have been developed using modelling procedures for both the EEZ and Regional scale classifications. Estimates of the depth-averaged maximum tidal current have been used to produce an estimate of the pattern of the bed stress experienced by the benthic community that is due to tidal current.
The maximum depth-averaged tidal currents (m/s) used for the MfE Marine Classification come from the NIWA Tide Model (Walters et al. 2001). Two algorithms have been developed for determining the average maximum current. The first is based on the concept of HAT (Highest Astronomical Tide) that is commonly used to describe the absolute maximum height that a tide could achieve and the other uses the concept that the M2 current will govern the maximum. The M2- based maximum current method has been chosen for generating the EEZ scale tidal current climatology. The principle of the M2-based maximum current method is to take the direction of the semi-major axis of the M2 tidal ellipse and find the magnitude of all the other tides at that angle and sum them. This method uses the concept that the
M2 current will govern the maximum current. The model output are produced on a spherical polar coordinate system (longitude and latitude) that was converted to Mercator projection and the International Hayford Spheroid.