During the project three oceanographic cruises were performed on board of the Argentinean ice breaker “Almirante Irizar” in the three austral winters 2004-2005, 2005-2006 e 2006-2007.

451 temperature profiles with XBT and 35 profiles of temperature and salinity with XCTD probes were collected on the Drake Strait, the Weddell Sea and between the northern tip of the Antarctica Paeninsula and the Orcadas Islands.

Data are acquired from the 7th offebruary and the sond were launched with a resolution of 20' of latitude to 70° ad 15' for higher latitudes, to beter define the thermal suthern front. ON the way back measurements are token from 68°S 28°W untill the Orcadas island platform

The main aim of the project was the study of the variability of the Mixed Layer and the estimate of the heat content on the first 700 m of the water column, and the large scale representation of the surace and subsurface structure of the ACC.

Analysis:

- Data from the Weddell sea were used to estimate the changes in temperature of the Warm Deep Water (WDW).

- Data from the Drake Passage were used to estimate the baroclinic transport, using WOCE section on the same area to infer statistical relation between temperatures and salinities.

- 3D OGCM models were used to study by means of Lagrangian diagnostics the water mass transformations on the Southern Ocean and their interannual variability. In particular the representation of the downwelling-upwelling cycle was reconstructed positioning particles on the water formation area and integrating them till the moment they resurface.

- The bio geochemical model PISCES was used to study the relative role of the biological and physical pump in the Southern Ocean with the aim of understanding the main mechanism of the CO2 sequestration.

- During the project was elaborated an experimental methodology useful to estimate the ML depth by means vertical profiles of temperature and salinity, using also data from CANOPO cruises. Finally, was investigated the role of the coherent structures, peculiar of the 2D geostrophic turbulence, on the ACC dynamics analyzing historical Lagrangian Data.