Upper Océan Thermal Structure and Fronts Between
New Zealand and the Ross Sea
(Austral Summer 1994-1995 and 1995-1996)
A. Russo1, A. Artegiani1, G. Budillon2, E. Paschini1 and G. Spezie2
1 Istituto di Ricerche sulla Pesca Marittima, CNR Ancona, Italy
2Istituto di Meteorologia e Oceanografia, IUN Napoli, Italy
Abstract
This paper describes the upper océan thermal structure between New Zealand
and the Ross Sea, and its évolution 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 dérivé 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.
1 Introduction
The Antarctic Circumpolar Current (ACC) is the main feature of the Southern
Océan and its relevance is recognised by a number of scientific works. This current flows ail around Antarctica, going from west to east. From earlier observations, the ACC flow has been related to the presence of fronts, whose number,
names and définition criteria change with time and investigators [1,2].In the présent work, we define these fronts using the most recent criteria available [2-4].
According to Orsi et al. [3], the ACC has as its northern limit the Subtropical
Front (STF) and as Southern limit the Boundary (Bdy). Within these limits, three
other fronts hâve been individuated, each of them corresponding to a local maximum of the geostrophic transport. From north to south, they are the
SubAntarctic Front (SAF), the Polar Front (PF) and the Southern front.
In the area covered by our data, from 172 to 180°E, the STF is very close to the
New Zealand and the Ross Sea
(Austral Summer 1994-1995 and 1995-1996)
A. Russo1, A. Artegiani1, G. Budillon2, E. Paschini1 and G. Spezie2
1 Istituto di Ricerche sulla Pesca Marittima, CNR Ancona, Italy
2Istituto di Meteorologia e Oceanografia, IUN Napoli, Italy
Abstract
This paper describes the upper océan thermal structure between New Zealand
and the Ross Sea, and its évolution 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 dérivé 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.
1 Introduction
The Antarctic Circumpolar Current (ACC) is the main feature of the Southern
Océan and its relevance is recognised by a number of scientific works. This current flows ail around Antarctica, going from west to east. From earlier observations, the ACC flow has been related to the presence of fronts, whose number,
names and définition criteria change with time and investigators [1,2].In the présent work, we define these fronts using the most recent criteria available [2-4].
According to Orsi et al. [3], the ACC has as its northern limit the Subtropical
Front (STF) and as Southern limit the Boundary (Bdy). Within these limits, three
other fronts hâve been individuated, each of them corresponding to a local maximum of the geostrophic transport. From north to south, they are the
SubAntarctic Front (SAF), the Polar Front (PF) and the Southern front.
In the area covered by our data, from 172 to 180°E, the STF is very close to the