Currents off the west coast of Northland, New Zealand

The concept of a southward-flowing West Auckland Current off the west coast of Northland has become an accepted feature of the ocean circulation around New Zealand. Knowledge of this flow is based on sparse data collected in the 1950s. Here we quantify the flows in the area for the first time using a current meter array deployed for a year (2003-2004) across the shelf and slope offshore of Hokianga Harbour and three hydrographic surveys along a transect coincident with the current meter array. Flows are found to be weak, and dominated by the variability. There is a southeastward drift in the mean flow offshore of the 1000-m isobath, with a northwestward mean found inshore of this. The offshore flows appear to result from large-scale sea surface height gradients, while the inshore flows respond to wind forcing in a complex manner.