Seasonal observations of the Subantarctic Front and Subantarctic Mode Water to the south-east of New Zealand

Hydrographic surveys over the Campbell Plateau and off the shelf edge reveal new features of the circulation to the south-east of New Zealand. These include persistent, strong flows around the Campbell Plateau associated with the Subantarctic Front on the south-eastern flank and a cyclonic circulation around the Bounty Trough on the northern flank. Flows are weaker on the Plateau itself and appear to be steered by the topography. Strong buoyancy loss to the atmosphere and the quiescent flow regime suggest the Plateau as a potential site for Subantarctic Mode Water formation. Hydrographic data from three comprehensive surveys in 1998 and 1999 supplemented with temperature data collected from cruises of opportunity, moored thermistor records and historical data are used to investigate the seasonal evolution of the water column in the region. The cooling and freshening of SAMW between the Tasman Sea and the South West Pacific Basin is examined.