SAVEX South Atlantic Variability Experiment

The Southern Ocean (SO) may seem like a remote part of the planet that has little importance to the every day lives of most people. But with increasing knowledge about its oceanography and biology, scientists are rapidly coming to realize that it is arguably the Earth's most important ocean. It is the only water body that completely circles the globe, providing the crucial link between all of the worlds' oceans. Physical processes in the SO influence all other oceans in significant ways, by closing the global thermohaline circulation and linking climatic processes from the Artic to the Antarctic. Its physical structure and dynamics support extremely rich and important biological resources including key species across all trophic levels from primary producers to top predators. This unique connectivity and biology also brings strategic importance for a wide range of oceanic activities, including commercial exploitation, transport, and conservation, which together bring the potential of conflicts between competing interests. Yet because of the cost and logistic challenges the SO presents to direct observation, it is the also arguably the least studied ocean, especially during winter and in its southern and seasonally ice covered regions, which are of profound importance both in terms of their physical oceanography and ecosystems. With growing public concern about the effects of human activities on climate and the consequences of rapidly increasing marine exploitation for oceanic ecosystems, the need for monitoring and understanding its physical dynamics and linking these to the biological processes that depend on them is becoming critical, as is the need for appropriate fine-scale ocean data for increasingly sophisticated models to provide the basis for understanding climate. A recent study argued that an observed warming of the SO is man-made and related to a southward shift of the Antarctic Circumpolar Current (ACC) caused by an increase in zonal winds. However, this is based on coarse-resolution modeling, and whilst there has been some support for this idea based on satellite studies, it is important to note that satellites are only really effective at tracking particular fronts, not the whole ACC. Many issues consequently remain unresolved, particularly: Does the position of the ACC change in a systematic way in response to changes in winds? We try to address this question, by equipping strategically chosen, deep-diving marine mammal species with state-of-the-art animal-borne oceanographic instruments. Programmes such as the Global Ocean Observation System will enable the assimilation of such data into ocean circulation models, with the intention of accurately representing and predicting climate variability on seasonal and longer timescales. This project will make its contributions at a particularly advantageous time for polar ocean studies, during the International Polar Year (IPY). During this time, a global concerted effort will be made to observe and interpret all aspects of high-latitude oceanography during this time of rapid change in the polar seas and when there is a growing realization of the importance they have for global climate Thanks to our technological developments in data collection, storage and communication, IPY will have our polar animals themselves as an important part of the observational and exploratory team to help us get data on places important to both them and us. The instruments collect and store behavioural and hydrographic data and relay them via the Argos System back to servers at the Sea Mammal Research Unit. This will provide a large high-resolution hydrographic data set covering areas of ocean at the fringes of the South Atlantic which is strategically important to ocean and climate modelling, but which are still relatively data sparse due to logistic difficulties.