CarboChange - Southern ocean

The Southern Ocean (SO) is a major part of the global ocean circulation and plays an important role in the global climate system. It is a global ocean connector, acting as the crossroads of the global ocean circulation. The formation and blending of water masses in the SO cause changes in the northward flow of the Meridional Overturning Circulation and as a consequence, in the Earth’s climate. There have been numerous studies of the SO but a full understanding is difficult to achieve due to the complexity of the processes in which different water masses are formed and mixed. Despite much scientific effort and a large amount of literature on water mass formation, circulation and exchange within the SO, the need for a full understanding is still required.

In the CarboChange project a study was conducted to clarify some of these aspects through an extended method for data analysing: the Optimum Multiparametric analysis was further developed within the project, also taking into account the remineralisation of organic matter as an improvement.  Data was downloaded from existing databases for the analysis. The aim of this work was to provide an accurate estimation of the integration and distribution of the most representative water masses of the SO.  A total of 11 source water masses were selected to accurately describe the physical and biochemical properties of the SO. Shelf surface waters were included in order to accommodate the complex shelf processes involved in the formation of Antarctic bottom waters.

The principal patterns of the thermohaline circulation of the SO can be identified from the study results, which also showed that Circumpolar Deep Water is the most volumetrically important water mass in the SO, followed by Antarctic Bottom Water and North Atlantic Deep Water. The results could also give an idea of the time interval for the bottom ocean to respond to changes in the atmospheric anthropogenic gasses content. Additionally, these results can also be of relevant use in climate change monitoring studies as the SO is a very interesting area for climate research and most studies consider this ocean to be the most powerful place in CO2 uptake and distribution throughout the ocean. Thus, an estimation of the ventilation time of the bottom water masses formed in this ocean can be of great help.


Paula C. Pardo, Fiz F. Pérez, Antón Velo, Miguel Gilcoto : Water masses distribution in the Southern Ocean: improvement of an extended OMP (eOMP) analysis.