UPPER OCEAN THERMAL STRUCTURE AND FRONTS BETWEEN NEW ZEALAND AND THE ROSS SEA (AUSTRAL SUMMER 1994-1995 AND 1995-1996)

This paper describes the upper ocean thermal structure between New Zealand and the Ross Sea, and its evolution from the austral spring to summer 1994-95 on the basis of four high resolution XBT sections, and during the summer 1995-96 with two high resolution XBT sections. The area of investigation is almost completely (with the exception of the southernmost part) interested by the Antarctic Circumpolar Current (ACC). The main fronts (SubAntarctic Front, Polar Front and southern front) included in the ACC are individuated, and a new front, supposed to derive from a splitting of the SAF in a Northern SAF (NSAF) and a Southern SAF (SSAF), is identified. The NSAF is always located at the end of the Campbell Plateau, on the continental slope, and the SSAF is located around 58 °S, with the exception of the December 1994-January 1995 cruises. Going from spring to the end of the austral summer, the PF appears to retreat from north to south, while the southern front shows a stable position on the northern flanks of the Pacific-Antarctic and Southeast Indian Ridges. The thermal structure of the six sections reveals the presence of intense mesoscale dynamics, with cold nuclea of Antarctic Surface Water (AASW) detached from the PF and noticed up to 1000 km north of it.