Monitoring and Understanding Southern Ocean Variability and Its Impact on Climate: a Strategy for Sustained Observations

The Southern Ocean profoundly influences regional and global climate. Several unique features of the Southern Ocean contribute to this climate influence: the zonally unbounded nature of the circumpolar ocean; the fact that deep and intermediate layers in the ocean interior are exposed to direct atmospheric forcing there; and the presence of a vast extent of seasonally-varying sea ice. The Southern Ocean is also remote, and the environment is hostile. As a consequence, historical data is scarce and hypotheses regarding the climate impact of Southern Ocean processes have been difficult to formulate and test. For these reasons, design and implementation of an observing system for the Southern Ocean is a formidable challenge. However, recent advances in understanding and instrumentation mean that it is now feasible to obtain the sustained observations needed to describe and understand the Southern Ocean processes responsible for climate variability.